RETINAL DETACHMENT
SIGNS AND SYMPTOMS
There are three forms of retinal detachment:
1. Rhegmatogenous retinal detachment (RRD), which results from a retinal break. The vast majority of rhegmatogenous detachments are symptomatic, with patients reporting photopsiae, floating spots, peripheral visual field loss, central blurring of vision or metamorphopsia.
2. Exudative or serous retinal detachment (ERD), which results from fluid accumulation under the sensory retina without a retinal break. Exudative detachments do not generally present with photopsiae but may be associated with moderate vision loss, metamorphopsia or a visual field deficit.
3. Tractional retinal detachment (TRD), which results from the pull of proliferative fibrovascular vitreal strands. Tractional detachments are typically asymptomatic unless central vision is threatened, in which case the patient can suffer severe and abrupt vision loss.
In cases of extensive unilateral retinal detachment, you may observe a relative afferent pupillary defect. Intraocular pressure may be reduced in eyes with acute retinal detachment.
Ophthalmoscopy in cases of RRD usually reveals a clumping of pigment cells within the anterior vitreous (Shaffer's sign). There may be an area of white or grayish elevated retina adjacent to the instigating retinal break. If a significant area of the retina is involved, you may note a milky, lackluster appearance with undulating retinal folds.
A rhegmatogenous detachment will not change position with changes in body posture, however it may shift and then return to its original orientation with quick eye movements. Associated findings may include posterior vitreous detachment and preretinal or vitreal hemorrhage. Retinal pigment epithelial hyperplasia may be noted in cases of long-standing retinal detachment (pigment demarcation line), and is a good prognostic feature.
ERD appears clinically as a focal, serous elevation of the retina, which shifts position with changes in posture and eye movement. The subretinal fluid obeys gravity, always affecting the lowest aspect of the eye. Ophthalmoscopy reveals a smooth, translucent, dome-shaped protrusion of the retina. There are usually no hemorrhages, except in cases of associated retinal vasculopathy.
TRD is always associated with vitreal strands and membranes. It appears as a concave, smooth-surfaced detachment with marginal fibrovascular bands emanating into the vitreous body. It is sometimes difficult to assess where the necrotic retina ends and the vitreal membranes begin. Very often, this area encircles an intact posterior pole, resulting in a retinal "pseudo-hole." TRDs are dense and immobile. This motility lends itself well to ancillary testing with ultrasonography.
PATHOPHYSIOLOGY
All retinal detachments involve the sensory retina dissecting from the underlying pigment epithelial layer by subretinal fluid. In rhegmatogenous detachments, this fluid is liquefied vitreous, which accesses the subretinal space via a retinal break. In exudative detachments, the fluid is derived from the choroid, passing through a defective Bruch's membrane. The origin of the subretinal fluid in tractional detachments is unknown. Both passive and active movement of subretinal fluid induce progression of retinal detachments, leading to partial or total loss of vision in some patients.
Retinal breaks are the predisposing factor in patients with rhegmatogenous detachment. These may result from preexisting conditions or ocular trauma. Some of the more common entities associated with RRD include lattice degeneration, flap tears, atrophic holes, operculated retinal breaks, and acquired retinoschisis with both inner and outer holes. As the retinal tissue loses its connection to the RPE, it becomes edematous and dysfunctional. Without surgical intervention, death of this tissue occurs within 48 to 72 hours.
Exudative detachments are relatively rare, occurring in association with subretinal disorders that damage the RPE layer. These may include choroidal neoplasms, Vogt-Koyanagi-Harada syndrome, posterior scleritis, congenital optic disc anomalies (optic pits, morning glory syndrome, etc.), Coat's disease and uveal effusion syndrome.
Transudation of fluid through the RPE defects causes detachment of the otherwise normal sensory retina. As the fluid shifts with eye and head movements, the involved portion of the retina changes. This explains why most patients with ERDs suffer significantly less devastating visual compromise than those with RRDs or TRDs.
Tractional detachments occur only in proliferative vitreoretinopathies. The most common of these is proliferative diabetic retinopathy, but many TRDs are associated with ischemic retinal vein occlusions, sickle cell retinopathy, retinopathy of prematurity, toxocariasis and trauma.
The etiology of TRD involves fibrotic scaffolding of the vitreous along proliferative vascular networks which induce strong anterior tractional forces through vitreal shrinkage. These forces induce the sensory retina to separate from the underlying RPE.
Unlike rhegmatogenous or exudative detachments which tend to be abrupt, TRDs are often slow and insidious, progressing at the same rate as the associated fibrovascular proliferation. Peripheral TRDs are therefore rarely if ever noticed by the patient. Macular TRDs, on the other hand, tend to be symptomatic, unless the underlying disease process has already compromised visual acuity.
Showing posts with label medicine. health care. Show all posts
Showing posts with label medicine. health care. Show all posts
Friday, November 11, 2011
RETINITIS PIGMENTOSA
SIGNS AND SYMPTOMS
Patients with retinitis pigmentosa (RP) may present with varying symptoms. The onset is often gradual and insidious, and many patients fail to recognize the manifestations of this condition until it has progressed significantly. When patients do report symptoms, they commonly include difficulty with night vision (nyctalopia) as well as loss of peripheral vision.
Many patients with RP also experience photopsiae as the disorder progresses; typically they report small flashes of light or a twinkling, shimmering sensation in the midperipheral or peripheral field. These are believed to represent aberrant electrical impulses from the degenerating retina.
Central visual acuity is generally not affected until the very late stages of RP, although variants have been encountered that cause devastating macular compromise early in the disease course (e.g., X-linked recessive RP). Color vision is typically remains intact as long as visual acuity is better than 20/40.
Attenuation of the retinal arterioles is the earliest observable sign in RP. Retinal pigmentary changes occur in the form of fine mottling or granularity with surrounding areas of atrophy. Later, stellate pigment hyperplasia may be noted at perivascular locations in the midperipheral retina. These hyperplastic formations are often referred to as "bone spicules."
As the disorder progresses, general atrophy of the RPE and choriocapillaris ensues, exposing the larger choroidal vessels. The optic nerve head is often normal in early RP, but may demonstrate a waxy yellow or pale appearance later. RP has a strong correlation with acquired optic disc drusen. The macula, like the optic nerve, is usually unaffected in the early stages, but in some forms of RP may demonstrate preretinal gliosis ("cellophane maculopathy"), cystoid macular edema or focal RPE defects. Additional findings in RP include pigment cells in the vitreous ("tobacco dust sign"), posterior vitreous detachment and posterior subcapsular cataracts.
Most patients with retinitis pigmentosa are myopic, and many have keratoconus as well. Electrodiagnostic testing in RP shows a significantly diminished scotopic ERG as well as an abnormal EOG and dark adaptometry.
PATHOPHYSIOLOGY
Retinitis pigmentosa is believed to stem from a genetic defect, which leads to a disturbance in the retinal pigment epithelium (RPE) and the breakdown of the photoreceptors' outer segment disc membranes. The resultant accumulation of metabolic by-products disrupts retinal function, and manifests as lipofuscin deposition, retinal gliosis, photoreceptor loss, choriocapillaris occlusion and RPE hyperplasia. These RPE changes compromise the blood-retina barrier, resulting in subretinal leakage and macular edema in later stages. Because the affected photoreceptor cells in most cases are rods, the patient typically experiences visual difficulty under dark conditions, as well as peripheral field constriction.
There are many forms of retinitis pigmentosa, and while most present with similar findings and outcome, some presentations are atypical. RP may be classified on the basis of inheritance pattern (autosomal dominant, autosomal recessive, X-linked, simplex, multiplex), age of onset (congenital, childhood onset, juvenile onset, adult onset), predominant photoreceptor involvement (rod-cone, cone-rod), or location of retinal involvement (central, pericentral, sectoral, peripheral).
MANAGEMENT
Since there is no known treatment for retinitis pigmentosa, management calls for prompt diagnosis and subsequent counseling to maintain quality of life.
Always obtain visual fields and electrodiagnostic testing to confirm the diagnosis of RP; order serology if the diagnosis is unclear or other disorders are suspected.
Most experts recommend a pedigree analysis of patients once RP has been diagnosed. This is critical to determine the exact inheritance pattern of the patient's condition. Individuals should know the risk for their progeny or other family members developing the disease.
Recommend genetic counseling to help the patient deal with these issues. Implement low-vision services as the disorder begins to affect visual function. Field-expansion devices, infrared blocking sun lenses and contrast enhancing filters may be helpful. Periodic optometric follow-up is also important. Perform visual fields several times a year, and evaluate for cataract or macular edema at least annually.
CLINICAL PEARLS
Most patients with RP are diagnosed in the second or third generation of life. Because of the insidious nature of the disorder, the earliest indicators are often objective findings rather than subjective complaints. Some presentations are extremely subtle, particularly in the early stages. Perform a critical evaluation on all patients presenting with complaints of nyctalopia or peripheral field loss.
The diagnosis of RP is often based upon appearance, but many "masqueraders" exist, including rubella retinopathy, syphilitic retinopathy, CMV retinopathy, toxoplasmosis, cancer-associated retinopathy, retinal drug toxicity secondary to thioridazine, chlorpromazine or chloroquine, pigmented paravenous retinochoroidal atrophy, and traumatic retinopathy.
Understandably, the untreatable progressive nature of retinitis pigmentosa is extremely unsettling for the patient and their loved ones; it is often beneficial to recommend psychological or family counseling early in the disease.
Impress upon these patien
Patients with retinitis pigmentosa (RP) may present with varying symptoms. The onset is often gradual and insidious, and many patients fail to recognize the manifestations of this condition until it has progressed significantly. When patients do report symptoms, they commonly include difficulty with night vision (nyctalopia) as well as loss of peripheral vision.
Many patients with RP also experience photopsiae as the disorder progresses; typically they report small flashes of light or a twinkling, shimmering sensation in the midperipheral or peripheral field. These are believed to represent aberrant electrical impulses from the degenerating retina.
Central visual acuity is generally not affected until the very late stages of RP, although variants have been encountered that cause devastating macular compromise early in the disease course (e.g., X-linked recessive RP). Color vision is typically remains intact as long as visual acuity is better than 20/40.
Attenuation of the retinal arterioles is the earliest observable sign in RP. Retinal pigmentary changes occur in the form of fine mottling or granularity with surrounding areas of atrophy. Later, stellate pigment hyperplasia may be noted at perivascular locations in the midperipheral retina. These hyperplastic formations are often referred to as "bone spicules."
As the disorder progresses, general atrophy of the RPE and choriocapillaris ensues, exposing the larger choroidal vessels. The optic nerve head is often normal in early RP, but may demonstrate a waxy yellow or pale appearance later. RP has a strong correlation with acquired optic disc drusen. The macula, like the optic nerve, is usually unaffected in the early stages, but in some forms of RP may demonstrate preretinal gliosis ("cellophane maculopathy"), cystoid macular edema or focal RPE defects. Additional findings in RP include pigment cells in the vitreous ("tobacco dust sign"), posterior vitreous detachment and posterior subcapsular cataracts.
Most patients with retinitis pigmentosa are myopic, and many have keratoconus as well. Electrodiagnostic testing in RP shows a significantly diminished scotopic ERG as well as an abnormal EOG and dark adaptometry.
PATHOPHYSIOLOGY
Retinitis pigmentosa is believed to stem from a genetic defect, which leads to a disturbance in the retinal pigment epithelium (RPE) and the breakdown of the photoreceptors' outer segment disc membranes. The resultant accumulation of metabolic by-products disrupts retinal function, and manifests as lipofuscin deposition, retinal gliosis, photoreceptor loss, choriocapillaris occlusion and RPE hyperplasia. These RPE changes compromise the blood-retina barrier, resulting in subretinal leakage and macular edema in later stages. Because the affected photoreceptor cells in most cases are rods, the patient typically experiences visual difficulty under dark conditions, as well as peripheral field constriction.
There are many forms of retinitis pigmentosa, and while most present with similar findings and outcome, some presentations are atypical. RP may be classified on the basis of inheritance pattern (autosomal dominant, autosomal recessive, X-linked, simplex, multiplex), age of onset (congenital, childhood onset, juvenile onset, adult onset), predominant photoreceptor involvement (rod-cone, cone-rod), or location of retinal involvement (central, pericentral, sectoral, peripheral).
MANAGEMENT
Since there is no known treatment for retinitis pigmentosa, management calls for prompt diagnosis and subsequent counseling to maintain quality of life.
Always obtain visual fields and electrodiagnostic testing to confirm the diagnosis of RP; order serology if the diagnosis is unclear or other disorders are suspected.
Most experts recommend a pedigree analysis of patients once RP has been diagnosed. This is critical to determine the exact inheritance pattern of the patient's condition. Individuals should know the risk for their progeny or other family members developing the disease.
Recommend genetic counseling to help the patient deal with these issues. Implement low-vision services as the disorder begins to affect visual function. Field-expansion devices, infrared blocking sun lenses and contrast enhancing filters may be helpful. Periodic optometric follow-up is also important. Perform visual fields several times a year, and evaluate for cataract or macular edema at least annually.
CLINICAL PEARLS
Most patients with RP are diagnosed in the second or third generation of life. Because of the insidious nature of the disorder, the earliest indicators are often objective findings rather than subjective complaints. Some presentations are extremely subtle, particularly in the early stages. Perform a critical evaluation on all patients presenting with complaints of nyctalopia or peripheral field loss.
The diagnosis of RP is often based upon appearance, but many "masqueraders" exist, including rubella retinopathy, syphilitic retinopathy, CMV retinopathy, toxoplasmosis, cancer-associated retinopathy, retinal drug toxicity secondary to thioridazine, chlorpromazine or chloroquine, pigmented paravenous retinochoroidal atrophy, and traumatic retinopathy.
Understandably, the untreatable progressive nature of retinitis pigmentosa is extremely unsettling for the patient and their loved ones; it is often beneficial to recommend psychological or family counseling early in the disease.
Impress upon these patien
RETINAL MACROANEURYSM
SIGNS AND SYMPTOMS
The patient typically is in the 50 to 80 age range, and most commonly female. Approximately 50 percent of patients have concurrent systemic arterial hypertension. These patients also have an increased incidence of cardiovascular disease and arteriosclerosis.
Ophthalmoscopy reveals an isolated dilatation of a major arterial (or, rarely, venous) branch, which is unilateral in 90 percent of cases but may be multifocal. Most often, by the time the patient presents, the aneurysm has leaked significantly with exudate and extensive intra-retina and/or subretinal hemorrhage. Occasionally, you may note spontaneous pulsation of the aneurysm.
When there is extensive hemorrhage, you may have difficulty assessing retinal macroaneurysm as the cause; neovascularization is often misdiagnosed as the cause. If the focal dilatation is not apparent on ophthalmoscopy, use fluorescein angiography. With fluorescein angiography, the aneurysm hyperfluoresces early in the angiogram with a characteristic balloon appearance with later-phase leakage.
Frequently, the patient is asymptomatic. However, if the macula is involved, the patient will present with reduced acuity and field. In these cases, permanent vision reduction is possible.
PATHOPHYSIOLOGY
An idiopathic weakening of the vessel wall leads to focal outpouching and aneurysm formation. Leakage occurs in extreme cases. However, there is no microvasculopathy as seen in diabetic retinopathy. Retinal macroaneurysm is strongly associated with hypertension, which may contribute to the vessel wall changes. Retinal macroaneurysm is also strongly associated with arteriosclerosis, retinal emboli and cardiovascular disease. Occasionally, retinal macroaneurysms occur within areas of retinal vein occlusions.
MANAGEMENT
Spontaneous sclerosis and occlusion typically occurs with macroaneurysms, particularly after hemorrhaging. Monitor asymptomatic non-leaking macroaneurysms at four- to six-month intervals. If leakage takes the form of exudation and/or hemorrhage that does not threaten the macula, then monitor every one to three months.
However, if hemorrhage threatens or involves the macula, or if there is persistent macular edema, photocoagulation is indicated. In these cases, moderately intense photocoagulation should be applied directly to the macroaneurysm so as not to produce complete occlusion of the involved artery. Venous macroaneurysms should be treated in the same manner. Also, if you observe a non-hemorrhagic macroaneurysm spontaneously pulsate, then direct photocoagulation should be used since rupture is likely.
CLINICAL PEARLS
In cases of unexplained intra- or subretinal hemorrhage, consider retinal macroaneurysm as the cause. If you don't readily observe the characteristic balloon ophthalmoscopically, use fluorescein angiography to identify the aneurysm.
Due to cardiovascular disease, these patients have a high rate of five-year mortality. Refer these patients to a cardiologist for evaluation. At the very least, order a fasting blood glucose, complete blood count with differential, fasting lipid profile and blood pressure evaluation.
The patient typically is in the 50 to 80 age range, and most commonly female. Approximately 50 percent of patients have concurrent systemic arterial hypertension. These patients also have an increased incidence of cardiovascular disease and arteriosclerosis.
Ophthalmoscopy reveals an isolated dilatation of a major arterial (or, rarely, venous) branch, which is unilateral in 90 percent of cases but may be multifocal. Most often, by the time the patient presents, the aneurysm has leaked significantly with exudate and extensive intra-retina and/or subretinal hemorrhage. Occasionally, you may note spontaneous pulsation of the aneurysm.
When there is extensive hemorrhage, you may have difficulty assessing retinal macroaneurysm as the cause; neovascularization is often misdiagnosed as the cause. If the focal dilatation is not apparent on ophthalmoscopy, use fluorescein angiography. With fluorescein angiography, the aneurysm hyperfluoresces early in the angiogram with a characteristic balloon appearance with later-phase leakage.
Frequently, the patient is asymptomatic. However, if the macula is involved, the patient will present with reduced acuity and field. In these cases, permanent vision reduction is possible.
PATHOPHYSIOLOGY
An idiopathic weakening of the vessel wall leads to focal outpouching and aneurysm formation. Leakage occurs in extreme cases. However, there is no microvasculopathy as seen in diabetic retinopathy. Retinal macroaneurysm is strongly associated with hypertension, which may contribute to the vessel wall changes. Retinal macroaneurysm is also strongly associated with arteriosclerosis, retinal emboli and cardiovascular disease. Occasionally, retinal macroaneurysms occur within areas of retinal vein occlusions.
MANAGEMENT
Spontaneous sclerosis and occlusion typically occurs with macroaneurysms, particularly after hemorrhaging. Monitor asymptomatic non-leaking macroaneurysms at four- to six-month intervals. If leakage takes the form of exudation and/or hemorrhage that does not threaten the macula, then monitor every one to three months.
However, if hemorrhage threatens or involves the macula, or if there is persistent macular edema, photocoagulation is indicated. In these cases, moderately intense photocoagulation should be applied directly to the macroaneurysm so as not to produce complete occlusion of the involved artery. Venous macroaneurysms should be treated in the same manner. Also, if you observe a non-hemorrhagic macroaneurysm spontaneously pulsate, then direct photocoagulation should be used since rupture is likely.
CLINICAL PEARLS
In cases of unexplained intra- or subretinal hemorrhage, consider retinal macroaneurysm as the cause. If you don't readily observe the characteristic balloon ophthalmoscopically, use fluorescein angiography to identify the aneurysm.
Due to cardiovascular disease, these patients have a high rate of five-year mortality. Refer these patients to a cardiologist for evaluation. At the very least, order a fasting blood glucose, complete blood count with differential, fasting lipid profile and blood pressure evaluation.
PRESUMED OCULAR HISTOPLASMOSIS SYNDROME
SIGNS AND SYMPTOMS
Presumed ocular histoplasmosis syndrome (POHS) is characterized by the triad of:
1. Disseminated midperipheral choroiditis, consisting of infiltrates and scarring which appears as yellow-white punched-out lesions.
2. A macular or parafoveal subretinal neovascular membrane which appears as a grayish-green patch beneath the retina in the peripapillary and foveal areas, with or without subretinal blood, exudate or disciform scarring.
3. Atrophy or scarring adjacent to the optic disc, which appears as a flat, whitish-brown lesion; the presentation varies depending on the amount of retinal pigmentary epithelial hyperplasia next to the optic disc.
POHS occurs bilaterally in 60 percent of cases. Patients are usually age 20-50. The eye remains remarkably quiet with virtually no aqueous or vitreous cells and minimal flare. In fact, most patients are asymptomatic until a choroiditis or subretinal neovascular membrane develops around the fovea. Optic disc edema is an occasional finding in active disease.
PATHOPHYSIOLOGY
Presumed ocular histoplamosis syndrome is a dimorphic fungal disease endemic to river valley climates. The designation "presumed" ocular histoplasmosis syndrome is used because researchers have not been able to isolate the Histoplasma Capsulatum organism in ocular tissue.
POHS probably results from infection by the blood-borne pathogen H. Capsulatum. This organism has an affinity for choroidal tissue and disseminates there following a systemic infection. The primary route of infection is through the lungs following an encounter with contaminated molds found in soil or from yeasts found in animals. During the initial infection, the patient may complain of fever, chills and malaise.
H. Capsulatum or its by-products produce a lymphocytic infiltration within the choroid. This results in the formation of granulomatous inflammatory masses that disrupt Bruch's membrane and the retinal pigment epithelium and compromise the outer layers of the retina. In most cases, the resulting peripheral choroidopathies are mild, producing only subtly observable clinical signs that heal without complications within a few weeks. Macular lesions possess serious ocular sequelae and progress through stages. Their presentation can lag behind the systemic infection by 30 years. Stress or immunocompromise increases the risk of macular involvement and POHS reactivation.
Stage 1 POHS maculopathy is marked by active choroiditis near the macula appearing as a yellow focus with fuzzy white borders.
Stage 2 POHS is characterized by SRNVM growth through compromised Bruch's membrane, serous sensory retinal detachment and RPE hyperplasia. Here, the RPE attempts to confine and envelop the SRNVM. This stage may abort and resolve leaving only a small residual scotoma.
Stages 3 and 4 consist of continued SRNVM progression, with sub-RPE hemorrhage and exudation.
Stage 5 is considered the end stage and is marked by maculopathy of more than two years and disciform scarring.
.
MANAGEMENT
The key to successful management of POHS and SRNVM is early detection. Laboratory tests are of no value in diagnosing POHS. Make the diagnosis via the history and clinical observation. Patient education along with Amsler grid and home monitoring of visual acuity help uncover reactivated or macular disease.
Early asymptomatic active retinal lesions are sometimes treated with oral or depot injections of steroids to reduce inflammation and the risk of macular disease. This is controversial given a lack of firm evidence that steroid or antifungal therapies are beneficial.
Numerous studies demonstrate the benefit of photocoagulation in cases with macular involvement. If you suspect an SRNVM, order fluorescein angiography. If angiography reveals an SRNVM, refer the patient for laser treatment. Follow-up care is critical due to the high incidence of recurrence following treatment of SRNVM.
CLINICAL PEARLS
The differential diagnosis of POHS includes both inflammatory and noninflammatory chorioretinal diseases. Consider diagnoses such as angioid streaks, toxoplasmosis, toxocariasis, recurrent multifocal choroiditis, birdshot choroiditis, punctate inner choroidopathy, acute posterior multifocal placoid pigment epitheliopathy, serpiginous choroidopathy and diffuse unilateral subacute neuroretinitis.
If one eye has a disciform scar, there is a 30 percent chance the fellow eye will develop an SRNVM.
Patients who have POHS frequently have a history of exposure to pigeons or chickens. It is frequently thought that avian fecal matter is a vector of spreading disease.
Presumed ocular histoplasmosis syndrome (POHS) is characterized by the triad of:
1. Disseminated midperipheral choroiditis, consisting of infiltrates and scarring which appears as yellow-white punched-out lesions.
2. A macular or parafoveal subretinal neovascular membrane which appears as a grayish-green patch beneath the retina in the peripapillary and foveal areas, with or without subretinal blood, exudate or disciform scarring.
3. Atrophy or scarring adjacent to the optic disc, which appears as a flat, whitish-brown lesion; the presentation varies depending on the amount of retinal pigmentary epithelial hyperplasia next to the optic disc.
POHS occurs bilaterally in 60 percent of cases. Patients are usually age 20-50. The eye remains remarkably quiet with virtually no aqueous or vitreous cells and minimal flare. In fact, most patients are asymptomatic until a choroiditis or subretinal neovascular membrane develops around the fovea. Optic disc edema is an occasional finding in active disease.
PATHOPHYSIOLOGY
Presumed ocular histoplamosis syndrome is a dimorphic fungal disease endemic to river valley climates. The designation "presumed" ocular histoplasmosis syndrome is used because researchers have not been able to isolate the Histoplasma Capsulatum organism in ocular tissue.
POHS probably results from infection by the blood-borne pathogen H. Capsulatum. This organism has an affinity for choroidal tissue and disseminates there following a systemic infection. The primary route of infection is through the lungs following an encounter with contaminated molds found in soil or from yeasts found in animals. During the initial infection, the patient may complain of fever, chills and malaise.
H. Capsulatum or its by-products produce a lymphocytic infiltration within the choroid. This results in the formation of granulomatous inflammatory masses that disrupt Bruch's membrane and the retinal pigment epithelium and compromise the outer layers of the retina. In most cases, the resulting peripheral choroidopathies are mild, producing only subtly observable clinical signs that heal without complications within a few weeks. Macular lesions possess serious ocular sequelae and progress through stages. Their presentation can lag behind the systemic infection by 30 years. Stress or immunocompromise increases the risk of macular involvement and POHS reactivation.
Stage 1 POHS maculopathy is marked by active choroiditis near the macula appearing as a yellow focus with fuzzy white borders.
Stage 2 POHS is characterized by SRNVM growth through compromised Bruch's membrane, serous sensory retinal detachment and RPE hyperplasia. Here, the RPE attempts to confine and envelop the SRNVM. This stage may abort and resolve leaving only a small residual scotoma.
Stages 3 and 4 consist of continued SRNVM progression, with sub-RPE hemorrhage and exudation.
Stage 5 is considered the end stage and is marked by maculopathy of more than two years and disciform scarring.
.
MANAGEMENT
The key to successful management of POHS and SRNVM is early detection. Laboratory tests are of no value in diagnosing POHS. Make the diagnosis via the history and clinical observation. Patient education along with Amsler grid and home monitoring of visual acuity help uncover reactivated or macular disease.
Early asymptomatic active retinal lesions are sometimes treated with oral or depot injections of steroids to reduce inflammation and the risk of macular disease. This is controversial given a lack of firm evidence that steroid or antifungal therapies are beneficial.
Numerous studies demonstrate the benefit of photocoagulation in cases with macular involvement. If you suspect an SRNVM, order fluorescein angiography. If angiography reveals an SRNVM, refer the patient for laser treatment. Follow-up care is critical due to the high incidence of recurrence following treatment of SRNVM.
CLINICAL PEARLS
The differential diagnosis of POHS includes both inflammatory and noninflammatory chorioretinal diseases. Consider diagnoses such as angioid streaks, toxoplasmosis, toxocariasis, recurrent multifocal choroiditis, birdshot choroiditis, punctate inner choroidopathy, acute posterior multifocal placoid pigment epitheliopathy, serpiginous choroidopathy and diffuse unilateral subacute neuroretinitis.
If one eye has a disciform scar, there is a 30 percent chance the fellow eye will develop an SRNVM.
Patients who have POHS frequently have a history of exposure to pigeons or chickens. It is frequently thought that avian fecal matter is a vector of spreading disease.
MACULAR HOLE
SIGNS AND SYMPTOMS
Idiopathic or senile macular holes are typically encountered in patients older than 60, and slightly more often in women than in men. Presenting symptoms include decreased central acuity, a central scotoma and/or metamorphopsia.
Macular holes develop in stages, including: foveal detachments (stage I), partial-thickness holes (stage II), and full-thickness holes (stage III). A stage IV macular hole is an advanced full-thickness hole, with vitreous separation from the optic disc and macula. Depending on the stage, vision may range from 20/20 to <20/400; however, in full-thickness macular holes, the acuity is generally 20/80 to 20/200.
Patients usually report a rather abrupt loss of central vision. A full-thickness macular hole clinically appears as a round, brick-colored lesion in the center of the macula, usually one-third to two-thirds of a disc diameter.
The surrounding retinal tissue appears gray and elevated, and often there are small yellow deposits within the hole, reminiscent of drusen. Foveal detachments and partial-thickness holes do not appear red, but rather present as a loss of the foveolar depression with the development of a central yellow spot or ring. Stage II holes are accompanied by a red, crescent-shaped retinal break at the lesion's edge. Fluorescein angiography reveals an RPE "window defect" with early-stage hyperfluorescence.
PATHOPHYSIOLOGY
Controversy surrounds the etiology of idiopathic macular holes. Diverse mechanisms have been proposed, including systemic vascular disease, hormonal variations, cystic retinal degeneration, anterior vitreoretinal traction, and tangential vitreoretinal tractional forces.
Currently, the most widely held theory proposes that pre-foveal vitreal shrinkage induces tangential traction on the fovea, eventually promoting hole formation. As contraction ensues, the tangential tugging at the fovea induces a separation of the sensory retina from the underlying RPE. The foveal retina, without a firm attachment to the RPE, suffers a compromised nutrient supply and loses its ability to eliminate waste.
Ultimately, the sensory retina atrophies, forming a break and progressing to a full-thickness hole. Macular holes may also result from chronic macular edema, solar retinopathy and blunt ocular trauma.
MANAGEMENT
In the past, the only management for macular holes was patient education, periodic observation in the affected and fellow eye, and the use of protective eyewear.
More recently, research has shown some benefit to surgical excision of the macular vitreoretinal adhesions in eyes at risk for full-thickness holes. The procedure involves pars plana vitrectomy, excision of the attached cortical vitreous and gas/fluid exchange. Growth factors such as transforming growth factor-b2 have been used to induce regeneration of the macular tissue. This procedure has achieved moderate success. Candidates for surgical intervention must have 20/50 visual acuity or worse, and a stage III or IV macular hole in at least one eye.
For cases that do not lend themselves to surgical intervention, consider low vision services.
CLINICAL PEARLS
Idiopathic macular holes affect the elderly. The astute clinician must consider this entity in the differential diagnosis of older patients who present with reduced visual acuity and a seemingly unremarkable examination.
The best way to observe the macula involves a contact fundus lens, be it a standard Goldmann three-mirror goniolens or any of the newer, more compact funduscopy lenses.
For suspected macular holes that appear equivocal or do not lend themselves to observation, consider the Watzke-Allen test. A vertical beam of light is presented to the fovea, using a Maddox rod, slit lamp beam with a fundus lens or a direct ophthalmoscope. Ask the patient if the line is uniform or broken in the center-patients with macular compromise report a broken line.
Macular holes are rarely, if ever, self-limiting. It is your obligation to educate the patient about the nature of the condition, and make the appropriate referrals necessary to ensure maximal visual function.
Other important facts:
50 percent of Stage I holes will progress to Stage II or worse.
70 percent of Stage II holes will progress to Stage III.
Retinal consultation is advisable in Stage I and II holes.
Vitrectomy may be helpful in Stage I holes to prevent progression to Stage II; it may also improve vision.
Vitrectomy is helpful in Stage II holes to preserve vision.
Idiopathic or senile macular holes are typically encountered in patients older than 60, and slightly more often in women than in men. Presenting symptoms include decreased central acuity, a central scotoma and/or metamorphopsia.
Macular holes develop in stages, including: foveal detachments (stage I), partial-thickness holes (stage II), and full-thickness holes (stage III). A stage IV macular hole is an advanced full-thickness hole, with vitreous separation from the optic disc and macula. Depending on the stage, vision may range from 20/20 to <20/400; however, in full-thickness macular holes, the acuity is generally 20/80 to 20/200.
Patients usually report a rather abrupt loss of central vision. A full-thickness macular hole clinically appears as a round, brick-colored lesion in the center of the macula, usually one-third to two-thirds of a disc diameter.
The surrounding retinal tissue appears gray and elevated, and often there are small yellow deposits within the hole, reminiscent of drusen. Foveal detachments and partial-thickness holes do not appear red, but rather present as a loss of the foveolar depression with the development of a central yellow spot or ring. Stage II holes are accompanied by a red, crescent-shaped retinal break at the lesion's edge. Fluorescein angiography reveals an RPE "window defect" with early-stage hyperfluorescence.
PATHOPHYSIOLOGY
Controversy surrounds the etiology of idiopathic macular holes. Diverse mechanisms have been proposed, including systemic vascular disease, hormonal variations, cystic retinal degeneration, anterior vitreoretinal traction, and tangential vitreoretinal tractional forces.
Currently, the most widely held theory proposes that pre-foveal vitreal shrinkage induces tangential traction on the fovea, eventually promoting hole formation. As contraction ensues, the tangential tugging at the fovea induces a separation of the sensory retina from the underlying RPE. The foveal retina, without a firm attachment to the RPE, suffers a compromised nutrient supply and loses its ability to eliminate waste.
Ultimately, the sensory retina atrophies, forming a break and progressing to a full-thickness hole. Macular holes may also result from chronic macular edema, solar retinopathy and blunt ocular trauma.
MANAGEMENT
In the past, the only management for macular holes was patient education, periodic observation in the affected and fellow eye, and the use of protective eyewear.
More recently, research has shown some benefit to surgical excision of the macular vitreoretinal adhesions in eyes at risk for full-thickness holes. The procedure involves pars plana vitrectomy, excision of the attached cortical vitreous and gas/fluid exchange. Growth factors such as transforming growth factor-b2 have been used to induce regeneration of the macular tissue. This procedure has achieved moderate success. Candidates for surgical intervention must have 20/50 visual acuity or worse, and a stage III or IV macular hole in at least one eye.
For cases that do not lend themselves to surgical intervention, consider low vision services.
CLINICAL PEARLS
Idiopathic macular holes affect the elderly. The astute clinician must consider this entity in the differential diagnosis of older patients who present with reduced visual acuity and a seemingly unremarkable examination.
The best way to observe the macula involves a contact fundus lens, be it a standard Goldmann three-mirror goniolens or any of the newer, more compact funduscopy lenses.
For suspected macular holes that appear equivocal or do not lend themselves to observation, consider the Watzke-Allen test. A vertical beam of light is presented to the fovea, using a Maddox rod, slit lamp beam with a fundus lens or a direct ophthalmoscope. Ask the patient if the line is uniform or broken in the center-patients with macular compromise report a broken line.
Macular holes are rarely, if ever, self-limiting. It is your obligation to educate the patient about the nature of the condition, and make the appropriate referrals necessary to ensure maximal visual function.
Other important facts:
50 percent of Stage I holes will progress to Stage II or worse.
70 percent of Stage II holes will progress to Stage III.
Retinal consultation is advisable in Stage I and II holes.
Vitrectomy may be helpful in Stage I holes to prevent progression to Stage II; it may also improve vision.
Vitrectomy is helpful in Stage II holes to preserve vision.
IDIOPATHIC CENTRAL SEROUS CHORIORETINOPATHY
SIGNS AND SYMPTOMS
Patients with idiopathic central serous chorioretinopathy (ICSC) usually present with complaints of sudden onset, unilateral distortion or blurring of central vision. They may report metamorphopsia, decreased color perception, or even a relative central scotoma. There is typically no pain and no history of recent trauma.
Evaluation reveals no external signs of disease nor inflammation, although a hyperopic refractive shift is often noted in the affected eye. Funduscopic examination shows a serous elevation of the macula with a loss of the foveal light reflex. There may also be an underlying area of RPE detachment. Patients with ICSC are typically young, with most cases occurring in the early to mid-thirties; white males appear to be the most commonly affected group. Those individuals with "Type A" personalities seem to be particularly predisposed to this condition.
PATHOPHYSIOLOGY
Although the true etiology of ICSC is unknown, emotional stress or anxiety appears to be a common element. It is believed that, in certain individuals, vasomotor instability from sympathetic nervous stimulation may induce local weaknesses in Bruch's membrane. Such weaknesses allow serous fluid to extravasate from the choriocapillaris under the macula (through a defect in the RPE), creating a focal detachment of the sensory retina. In most instances, the fluid eventually resolves, but the condition may be recurrent in as many as 50 percent of affected individuals. In these patients, cystic yellow lesions known as "lemon drops" and areas of mild RPE hyperplasia are often seen.
MANAGEMENT
Most cases of ICSC are self-limiting, and resolve spontaneously over a period of weeks to months. The prognosis for visual recovery is excellent-up to 60 percent can expect to regain 20/20 acuity. While many cases of ICSC require no intervention, recent studies have supported the use of oral indomethacin to hasten the recovery time. In addition, focal laser photocoagulation may be effective in repairing the RPE at the site of the leakage. Most practitioners, however, will consider this therapy only in cases that fail to recover within a reasonable period of time, highly recurrent cases, or cases in which the patients are overtly symptomatic and insist on definitive treatment.
CLINICAL PEARLS
An experienced, astute clinician can often diagnose ICSC based solely upon the history and chief complaint-a young, anxious patient who presents with unilateral metamorphopsia of recent onset.
The classic fundus appearance is usually best seen with binocular indirect ophthalmoscopy.
In subtle or atypical cases, fluorescein angiography offers the definitive diagnosis.
Patients presenting with ICSC for the first time should be reassured, counseled as to the natural course of the condition, and monitored every three to four weeks for three to four months as resolution occurs. Failure to resolve within six months is probably an indication for more aggressive therapy, such as focal laser photocoagulation.
Longstanding ICSC may result in a "sick RPE" with permanent visual reduction.
Patients with idiopathic central serous chorioretinopathy (ICSC) usually present with complaints of sudden onset, unilateral distortion or blurring of central vision. They may report metamorphopsia, decreased color perception, or even a relative central scotoma. There is typically no pain and no history of recent trauma.
Evaluation reveals no external signs of disease nor inflammation, although a hyperopic refractive shift is often noted in the affected eye. Funduscopic examination shows a serous elevation of the macula with a loss of the foveal light reflex. There may also be an underlying area of RPE detachment. Patients with ICSC are typically young, with most cases occurring in the early to mid-thirties; white males appear to be the most commonly affected group. Those individuals with "Type A" personalities seem to be particularly predisposed to this condition.
PATHOPHYSIOLOGY
Although the true etiology of ICSC is unknown, emotional stress or anxiety appears to be a common element. It is believed that, in certain individuals, vasomotor instability from sympathetic nervous stimulation may induce local weaknesses in Bruch's membrane. Such weaknesses allow serous fluid to extravasate from the choriocapillaris under the macula (through a defect in the RPE), creating a focal detachment of the sensory retina. In most instances, the fluid eventually resolves, but the condition may be recurrent in as many as 50 percent of affected individuals. In these patients, cystic yellow lesions known as "lemon drops" and areas of mild RPE hyperplasia are often seen.
MANAGEMENT
Most cases of ICSC are self-limiting, and resolve spontaneously over a period of weeks to months. The prognosis for visual recovery is excellent-up to 60 percent can expect to regain 20/20 acuity. While many cases of ICSC require no intervention, recent studies have supported the use of oral indomethacin to hasten the recovery time. In addition, focal laser photocoagulation may be effective in repairing the RPE at the site of the leakage. Most practitioners, however, will consider this therapy only in cases that fail to recover within a reasonable period of time, highly recurrent cases, or cases in which the patients are overtly symptomatic and insist on definitive treatment.
CLINICAL PEARLS
An experienced, astute clinician can often diagnose ICSC based solely upon the history and chief complaint-a young, anxious patient who presents with unilateral metamorphopsia of recent onset.
The classic fundus appearance is usually best seen with binocular indirect ophthalmoscopy.
In subtle or atypical cases, fluorescein angiography offers the definitive diagnosis.
Patients presenting with ICSC for the first time should be reassured, counseled as to the natural course of the condition, and monitored every three to four weeks for three to four months as resolution occurs. Failure to resolve within six months is probably an indication for more aggressive therapy, such as focal laser photocoagulation.
Longstanding ICSC may result in a "sick RPE" with permanent visual reduction.
HOLLENHORST PLAQUE
SIGNS AND SYMPTOMS
The patient typically is elderly and often has concurrent history of hypertension, diabetes, carotid artery disease, peripheral vascular disease, hypercholesterolemia, hyperlipidemia, and/or atherosclerosis. The patient may be totally asymptomatic and the plaque(s) may be found on routine eye exam.
However, the patient may have previously experienced transient episodes of monocular blindness (amaurosis fugax). Rarely, the patient has experienced a transient ischemic attack with hemiparesis, paraesthesia, and/or aphasia. These episodic bouts of amaurosis fugax may be quite frequent, and may last from several seconds to several minutes. Rarely does the patient have any lasting visual deficits.
Frequently, the patient previously experiencing amaurosis fugax will not exhibit retinal emboli, but may have arteriolar narrowing and sheathing. A Hollenhorst plaque appears as a bright, glistening, refractile plaque, usually at the bifurcation of a retinal arteriole. These have the propensity to break up and move, and may not be present at subsequent visits.
PATHOPHYSIOLOGY
The Hollenhorst plaque is an embolus composed of cholesterol that forms from an ulcerated ipsilateral carotid artery plaque. The patient frequently has concurrent hypertension and elevated cholesterol levels. The stress on the arteries induced by hypertension leads to reduced elasticity of the vessels.
Cholesterol is deposited within the vessel walls and forms an atheroma, narrowing the artery. Turbulent blood flow over the atheroma can lead this plaque to ulcerate, which allows small particles to break off and flow within the blood stream. Eventually, the embolus enters a vessel whose caliber is too small to allow it to flow any further, and it lodges. Ischemia to the tissue occurs if blood flow is significantly impaired distal to the blockage. If the emboli lodges within a retinal vessel, then retinal ischemia with corresponding loss of vision occurs. The result may be a retinal artery occlusion.
In the case of cholesterol emboli, however, the blockage often quickly dislodges without permanent visual impairment. Instead, the patient experiences a brief interruption of vision and/or visual field (amaurosis fugax). Multiple bouts of amaurosis fugax may indicate multiple emboli. In cases where the patient is asymptomatic, yet a Hollenhorst plaque is visible, there is rarely permanent ischemia. This is because the cholesterol emboli are malleable and blood flow may be able to get past the emboli.
MANAGEMENT
There is no direct treatment of the visible emboli. In fact, because blood often can flow through an apparently complete blockage, direct removal is not necessary. In any case of retinal embolization, the concern must be further embolization with ensuing retinal infarct or cerebrovascular accident with permanent sequela of stroke. Survival rate decreases with the appearance of a retinal embolus. The primary cause of mortality in patients with retinal emboli is coronary artery disease and myocardial infarction.
A retinal embolus indicates significant systemic vascular disease. Refer the patient to an internist, vascular surgeon, or cardiologist for hypertension, coronary artery disease, diabetes, and carotid artery disease. A complete physical, carotid ultrasound, stress echocardiogram, fasting glucose and lipid levels, and blood chemistry with cardiac enzymes are indicated. Treatment of carotid stenosis, TIAs, and retinal emboli may include carotid endarterectomy, carotid angioplasty, or aspirin therapy, depending upon the risks of future ischemic events.
CLINICAL PEARLS
Patients with cholesterol emboli have a 15 percent mortality rate in the first year, 29 percent by the third year, and 54 percent by the seventh year. The main cause of mortality is cardiac death.
The patient, though in no apparent distress, must be referred to the proper medical specialist in order to appropriately manage the underlying systemic diseases and reduce morbidity and mortality.
The patient typically is elderly and often has concurrent history of hypertension, diabetes, carotid artery disease, peripheral vascular disease, hypercholesterolemia, hyperlipidemia, and/or atherosclerosis. The patient may be totally asymptomatic and the plaque(s) may be found on routine eye exam.
However, the patient may have previously experienced transient episodes of monocular blindness (amaurosis fugax). Rarely, the patient has experienced a transient ischemic attack with hemiparesis, paraesthesia, and/or aphasia. These episodic bouts of amaurosis fugax may be quite frequent, and may last from several seconds to several minutes. Rarely does the patient have any lasting visual deficits.
Frequently, the patient previously experiencing amaurosis fugax will not exhibit retinal emboli, but may have arteriolar narrowing and sheathing. A Hollenhorst plaque appears as a bright, glistening, refractile plaque, usually at the bifurcation of a retinal arteriole. These have the propensity to break up and move, and may not be present at subsequent visits.
PATHOPHYSIOLOGY
The Hollenhorst plaque is an embolus composed of cholesterol that forms from an ulcerated ipsilateral carotid artery plaque. The patient frequently has concurrent hypertension and elevated cholesterol levels. The stress on the arteries induced by hypertension leads to reduced elasticity of the vessels.
Cholesterol is deposited within the vessel walls and forms an atheroma, narrowing the artery. Turbulent blood flow over the atheroma can lead this plaque to ulcerate, which allows small particles to break off and flow within the blood stream. Eventually, the embolus enters a vessel whose caliber is too small to allow it to flow any further, and it lodges. Ischemia to the tissue occurs if blood flow is significantly impaired distal to the blockage. If the emboli lodges within a retinal vessel, then retinal ischemia with corresponding loss of vision occurs. The result may be a retinal artery occlusion.
In the case of cholesterol emboli, however, the blockage often quickly dislodges without permanent visual impairment. Instead, the patient experiences a brief interruption of vision and/or visual field (amaurosis fugax). Multiple bouts of amaurosis fugax may indicate multiple emboli. In cases where the patient is asymptomatic, yet a Hollenhorst plaque is visible, there is rarely permanent ischemia. This is because the cholesterol emboli are malleable and blood flow may be able to get past the emboli.
MANAGEMENT
There is no direct treatment of the visible emboli. In fact, because blood often can flow through an apparently complete blockage, direct removal is not necessary. In any case of retinal embolization, the concern must be further embolization with ensuing retinal infarct or cerebrovascular accident with permanent sequela of stroke. Survival rate decreases with the appearance of a retinal embolus. The primary cause of mortality in patients with retinal emboli is coronary artery disease and myocardial infarction.
A retinal embolus indicates significant systemic vascular disease. Refer the patient to an internist, vascular surgeon, or cardiologist for hypertension, coronary artery disease, diabetes, and carotid artery disease. A complete physical, carotid ultrasound, stress echocardiogram, fasting glucose and lipid levels, and blood chemistry with cardiac enzymes are indicated. Treatment of carotid stenosis, TIAs, and retinal emboli may include carotid endarterectomy, carotid angioplasty, or aspirin therapy, depending upon the risks of future ischemic events.
CLINICAL PEARLS
Patients with cholesterol emboli have a 15 percent mortality rate in the first year, 29 percent by the third year, and 54 percent by the seventh year. The main cause of mortality is cardiac death.
The patient, though in no apparent distress, must be referred to the proper medical specialist in order to appropriately manage the underlying systemic diseases and reduce morbidity and mortality.
ACQUIRED RETINOSCHISIS
SIGNS AND SYMPTOMS
The patient is nearly always asymptomatic. Rarely, the patient reports a sharp visual field defect corresponding to the area of the retinoschisis. Ophthalmoscopy reveals a smooth, stationary, bullous elevation of either the inferior-temporal or superior-temporal retina. The elevation may extend beyond the equator, and may rarely invade the posterior pole. The dome of the elevation is smooth and translucent. Blood vessels traverse the dome and cast shadows on the underlying structures. There is no pigmentation line unless a concurrent retinal detachment exists.
PATHOPHYSIOLOGY
Every eye over the age of eight years manifests peripheral cystic changes in the inner nuclear and outer plexiform layers of the retina. These spaces coalesce to form interlacing tunnels. If enough cystic spaces coalesce, the retina will form a retinoschisis, splitting into an inner and outer layer cavity. The superficial retinal layers comprise the inner layer, while the deeper layers of the retina and RPE represent the outer layer of the retinoschisis cavity.
There are technically two types of acquired retinoschisis. There is the typical degenerative retinoschisis, which presents as a shallow elevation of the inner retinal layers. There is also reticular degenerative retinoschisis, which presents in the traditional appearance of a bullous elevation.
In all types of acquired retinoschisis, either the inner layer or the outer layer, or both layers, may develop holes. Should holes develop in the inner layer of the retinoschisis, then liquid vitreous may flow into the fluid cavity. This doesn't change the prognosis. If there are outer layer holes as well, then liquid vitreous could enter the subretinal space and cause a rhegmatogenous retinal detachment. To this end, retinoschisis with both inner and outer layer holes has the potential to progress to rhegmatogenous retinal detachment. The risk of progression to rhegmatogenous retinal detachment in retinoschisis with double layer holes is 0.25 to 1.4 percent. The risk of detachment in retinoschisis without double layer holes is 0.024 percent. There is also potential for the splitting of the retina to continue with posterior extension of the retinoschisis.
MANAGEMENT
The risk of rhegmatogenous retinal detachment occurring in a retinoschisis (even with double layer holes) is exceedingly low, so there is no treatment beyond routine monitoring every six to 12 months. If possible, the retinoschisis should be photographed to monitor for progression. Because retinoschisis results in a sharply demarcated visual field defect, the stability can be monitored with a threshold visual field of the central 60 degrees.
CLINICAL PEARLS
While retinoschisis has the potential to enlarge and extend posteriorly and threaten the macula, its progression is extremely slow and may take months to years in order to threaten vision. Thus, a retinal consult is rarely urgent.
Because the RPE is not disrupted by retinoschisis, the RPE does not become hyperplastic and a pigment demarcation line will not form. If a pigment demarcation line is present in a retinoschisis, it should be taken as a sign that there is a concomitant retinal detachment.
The retinoschisis shows no movement or undulation upon eye movement or scleral indentation, whereas a retinal detachment does. Furthermore, scleral indentation will show preservation of the schisis cavity, as opposed to retinal detachment.
The patient is nearly always asymptomatic. Rarely, the patient reports a sharp visual field defect corresponding to the area of the retinoschisis. Ophthalmoscopy reveals a smooth, stationary, bullous elevation of either the inferior-temporal or superior-temporal retina. The elevation may extend beyond the equator, and may rarely invade the posterior pole. The dome of the elevation is smooth and translucent. Blood vessels traverse the dome and cast shadows on the underlying structures. There is no pigmentation line unless a concurrent retinal detachment exists.
PATHOPHYSIOLOGY
Every eye over the age of eight years manifests peripheral cystic changes in the inner nuclear and outer plexiform layers of the retina. These spaces coalesce to form interlacing tunnels. If enough cystic spaces coalesce, the retina will form a retinoschisis, splitting into an inner and outer layer cavity. The superficial retinal layers comprise the inner layer, while the deeper layers of the retina and RPE represent the outer layer of the retinoschisis cavity.
There are technically two types of acquired retinoschisis. There is the typical degenerative retinoschisis, which presents as a shallow elevation of the inner retinal layers. There is also reticular degenerative retinoschisis, which presents in the traditional appearance of a bullous elevation.
In all types of acquired retinoschisis, either the inner layer or the outer layer, or both layers, may develop holes. Should holes develop in the inner layer of the retinoschisis, then liquid vitreous may flow into the fluid cavity. This doesn't change the prognosis. If there are outer layer holes as well, then liquid vitreous could enter the subretinal space and cause a rhegmatogenous retinal detachment. To this end, retinoschisis with both inner and outer layer holes has the potential to progress to rhegmatogenous retinal detachment. The risk of progression to rhegmatogenous retinal detachment in retinoschisis with double layer holes is 0.25 to 1.4 percent. The risk of detachment in retinoschisis without double layer holes is 0.024 percent. There is also potential for the splitting of the retina to continue with posterior extension of the retinoschisis.
MANAGEMENT
The risk of rhegmatogenous retinal detachment occurring in a retinoschisis (even with double layer holes) is exceedingly low, so there is no treatment beyond routine monitoring every six to 12 months. If possible, the retinoschisis should be photographed to monitor for progression. Because retinoschisis results in a sharply demarcated visual field defect, the stability can be monitored with a threshold visual field of the central 60 degrees.
CLINICAL PEARLS
While retinoschisis has the potential to enlarge and extend posteriorly and threaten the macula, its progression is extremely slow and may take months to years in order to threaten vision. Thus, a retinal consult is rarely urgent.
Because the RPE is not disrupted by retinoschisis, the RPE does not become hyperplastic and a pigment demarcation line will not form. If a pigment demarcation line is present in a retinoschisis, it should be taken as a sign that there is a concomitant retinal detachment.
The retinoschisis shows no movement or undulation upon eye movement or scleral indentation, whereas a retinal detachment does. Furthermore, scleral indentation will show preservation of the schisis cavity, as opposed to retinal detachment.
CHOROIDAL MELANOMA
SIGNS AND SYMPTOMS
The benign choroidal melanoma, referred to clinically as a choroidal nevus, appears as a flat or slightly elevated slate gray lesion of the posterior fundus. The margins are typically indistinct, and often there are overlying areas of drusen noted within the nevus. In most instances, choroidal nevi remain under two disc diameters (DD) in size, although they may attain sizes of up to 5 DD in some cases.
The malignant choroidal melanoma, in contrast, appears as a mottled, often significantly elevated lesion, ranging in coloration from white to greenish-gray. As it grows, it may break through Bruch's membrane, taking on a mushroom-like appearance. Serous retinal detachments are commonly associated with this presentation. You may also observe overlying orange pigmentation known as lipofuscin. Most malignant melanomas are over 10 DD in size at the time of diagnosis. Most patients with choroidal melanomas are asymptomatic. However, should a significantly large lesion occur in proximity to the macula, the patient may present with metamorphopsia, acuity loss, visual field deficit and/or a hyperopic refractive shift.
PATHOPHYSIOLOGY
A choroidal melanoma represents a focal accumulation of melanocytes at the level of the uvea. In a choroidal nevus, these melanocytes are normal in both form and function. In malignant melanoma, the cells undergo neoplasia, reproducing at a faster rate than usual and resulting in a dysfunctional tumor mass. This tumor is capable of not only local extension but also of distant metastasis. While choroidal nevi do not typically lead to this type of damage, it is believed that they can convert to malignancy; the rate of malignant transformation over a 10-year period is estimated at 21 in 100,000.
Choroidal Nevus
MANAGEMENT
Nevi of 2 DD or less are harmless. Document the presentation with photography and, when possible, perform a B-scan and follow-up annually. Nevi between 2 and 5 DD are more suspicious. Either perform or refer for angiography to help differentiate the mass, and follow-up regularly at six-month intervals.
When the lesion is greater than 5 DD, consider it a malignant melanoma until proven otherwise. It may not require immediate treatment if relatively small and demonstrates no growth. But if the presentation suddenly changes dramatically or if sight is threatened, refer to a retinal specialist for treatment.
CLINICAL PEARLS
While a nevus is of little concern, malignant melanoma presents a potentially life-threatening situation because of its propensity toward metastasis. These tumors have been known to spread to the liver, lungs, skin and gastrointestinal tract.
Refer patients with newly detected malignant melanomas to a primary care physician for testing, which may include liver enzymes, carcinoembryonic antigen (CEA), neuroimaging, and chest CT.
The benign choroidal melanoma, referred to clinically as a choroidal nevus, appears as a flat or slightly elevated slate gray lesion of the posterior fundus. The margins are typically indistinct, and often there are overlying areas of drusen noted within the nevus. In most instances, choroidal nevi remain under two disc diameters (DD) in size, although they may attain sizes of up to 5 DD in some cases.
The malignant choroidal melanoma, in contrast, appears as a mottled, often significantly elevated lesion, ranging in coloration from white to greenish-gray. As it grows, it may break through Bruch's membrane, taking on a mushroom-like appearance. Serous retinal detachments are commonly associated with this presentation. You may also observe overlying orange pigmentation known as lipofuscin. Most malignant melanomas are over 10 DD in size at the time of diagnosis. Most patients with choroidal melanomas are asymptomatic. However, should a significantly large lesion occur in proximity to the macula, the patient may present with metamorphopsia, acuity loss, visual field deficit and/or a hyperopic refractive shift.
PATHOPHYSIOLOGY
A choroidal melanoma represents a focal accumulation of melanocytes at the level of the uvea. In a choroidal nevus, these melanocytes are normal in both form and function. In malignant melanoma, the cells undergo neoplasia, reproducing at a faster rate than usual and resulting in a dysfunctional tumor mass. This tumor is capable of not only local extension but also of distant metastasis. While choroidal nevi do not typically lead to this type of damage, it is believed that they can convert to malignancy; the rate of malignant transformation over a 10-year period is estimated at 21 in 100,000.
Choroidal Nevus
MANAGEMENT
Nevi of 2 DD or less are harmless. Document the presentation with photography and, when possible, perform a B-scan and follow-up annually. Nevi between 2 and 5 DD are more suspicious. Either perform or refer for angiography to help differentiate the mass, and follow-up regularly at six-month intervals.
When the lesion is greater than 5 DD, consider it a malignant melanoma until proven otherwise. It may not require immediate treatment if relatively small and demonstrates no growth. But if the presentation suddenly changes dramatically or if sight is threatened, refer to a retinal specialist for treatment.
CLINICAL PEARLS
While a nevus is of little concern, malignant melanoma presents a potentially life-threatening situation because of its propensity toward metastasis. These tumors have been known to spread to the liver, lungs, skin and gastrointestinal tract.
Refer patients with newly detected malignant melanomas to a primary care physician for testing, which may include liver enzymes, carcinoembryonic antigen (CEA), neuroimaging, and chest CT.
TOXOPLASMOSIS
SIGNS AND SYMPTOMS
The symptoms associated with ocular toxoplasmosis include unilateral, mild ocular pain, blurred vision and new onset of floating spots. Patients often describe their vision as hazy. Clinical findings may include granulomatous iritis, vitritis, optic disc swelling, neuroretinitis, vasculitis and retinal vein occlusion in the vicinity of the inflammation, in the actively involved eye. Funduscopically, active toxoplasmosis presents with white-yellow, choreoretinal lesions and vitreous cells. There may be old, inactive lesions in the fellow eye. Toxoplasmosis can produce cystoid macular edema and choroidal neovascularization.
PATHOPHYSIOLOGY
Toxoplasmosis is a disease provoked by the obligate intracellular protozoan Toxoplasma gondii. It is found in a variety of mammal and bird hosts. The most common intermediate host is the cat. It is one of the most frequent causes of retinochoroiditis in humans, with more than 60 percent of the United States population and up to 75 percent of the world's general population possessing some seropositive findings.
The systemic symptoms found in congenital toxoplasmosis consist of convulsions, calcification of the arterioles and choreoretinitis. In adults, toxoplasmosis is often contracted without sickness. A small percentage of individuals encounter self-limiting, flu-like symptoms at the time of inoculation.
Toxoplasma exists in humans in two forms: (1) actively motile tachyzoites and (2) encysted Toxoplasma gondii called brachyzoites. The oocysts that contain the organisms which produce infection are excreted in fecal material and may lie dormant in the soil until ingested by other animals, resulting in infection.
Human infection may occur from ingestion of contaminated or undercooked meat and dairy products, direct or indirect ingestion of cat feces and transplacental transmission from an infected mother to the fetus. Toxoplasmosis can only be transmitted to a fetus during maternal parastemia. Congenital toxoplasmosis accounts for the majority of cases encountered in clinical practice.
In most cases, the body is primed for infection or toxoplasmosis reactivation by an immune system failure. This may occur following contraction of human immunodeficiency syndrome (HIV) or with medical immunosupression following organ transplantation.
The inflammatory fundus lesions are composed of mononuclear cells, with a liberation of lymphocytes, macrophages, epithelioid and plasma cells. The resulting retinal vasculitis contributes to the breakdown of the blood-retinal barrier and leads to a compromise in retinal function, with subsequent destruction and thickening.
MANAGEMENT
The goal of management is twofold: (1) eradicate the parasite and (2) suppress the inflammatory response. The classic treatment regimen combines pyrimethamine (a 75mg loading dose, followed by 25mg PO BID administration) with sulfadiazine (2g loading dose, then 1g PO QID for 4 to 6 weeks). Both medications inhibit the folic acid metabolism necessary for toxoplasmosis to survive. Concurrent folinic acid, 3 to 5mg PO twice weekly helps to minimize any bone marrow toxicity produced by the pyramethamine.
Alternative antibiotic treatments include: (1) clindamycin, 300mg, PO QID used with sulfadiazine, for four to six weeks, (2) tetracycline, 2g loading then 250mg PO QID and sulfadiazine for four to six weeks, or (3) trimethoprim/sulfamethoxazole 160/800mg, one tablet PO BID, with or without clindamycin or prednisone, for the same duration.
In otherwise normal individuals, after beginning antibiotic therapy, add oral steroids at a dose of 20 to 80mg PO daily for four to six weeks. Periocular steroids are never indicated. Oral steroids without systemic antibiotics are expressly contraindicated.
Manage the anterior ocular inflammation with a cycloplegic that is appropriate for the disease's severity and a topical steroid Q2H/QID.
Systemic laboratory testing is indicated in active cases. The Sabin-Feldman methylene blue dye test (for Toxoplasma gondii), Serum antitoxoplasma antibody titer (for Toxoplasma gondii), Fluorescent Treponemal Antibody absorption test (for syphilis), purified protein derivative (for tuberculosis), chest x-ray (for sarcoid and TB), Toxocara Enzyme Linked Immunofluorescent Assay (for Toxocara canis) and Human Immunodefeciency Virus titer (for HIV) are among the important tests to order.
CLINICAL PEARLS
Since the organism may remain viable for up to 25 years and reactivation attacks are common, patient education is vital. If an outbreak is discovered in a community, provide education regarding the consumption of uncooked or under-cooked foods and the danger of untidy cats and/or their litter boxes.
In patients who have active infection, consider HIV/AIDS, especially if no other obvious means of immunosuppression are present. Surgical modalities, such as laser photocoagulation and cryopexy, have less value and are traditionally only recommended when the other modalities have failed.
The symptoms associated with ocular toxoplasmosis include unilateral, mild ocular pain, blurred vision and new onset of floating spots. Patients often describe their vision as hazy. Clinical findings may include granulomatous iritis, vitritis, optic disc swelling, neuroretinitis, vasculitis and retinal vein occlusion in the vicinity of the inflammation, in the actively involved eye. Funduscopically, active toxoplasmosis presents with white-yellow, choreoretinal lesions and vitreous cells. There may be old, inactive lesions in the fellow eye. Toxoplasmosis can produce cystoid macular edema and choroidal neovascularization.
PATHOPHYSIOLOGY
Toxoplasmosis is a disease provoked by the obligate intracellular protozoan Toxoplasma gondii. It is found in a variety of mammal and bird hosts. The most common intermediate host is the cat. It is one of the most frequent causes of retinochoroiditis in humans, with more than 60 percent of the United States population and up to 75 percent of the world's general population possessing some seropositive findings.
The systemic symptoms found in congenital toxoplasmosis consist of convulsions, calcification of the arterioles and choreoretinitis. In adults, toxoplasmosis is often contracted without sickness. A small percentage of individuals encounter self-limiting, flu-like symptoms at the time of inoculation.
Toxoplasma exists in humans in two forms: (1) actively motile tachyzoites and (2) encysted Toxoplasma gondii called brachyzoites. The oocysts that contain the organisms which produce infection are excreted in fecal material and may lie dormant in the soil until ingested by other animals, resulting in infection.
Human infection may occur from ingestion of contaminated or undercooked meat and dairy products, direct or indirect ingestion of cat feces and transplacental transmission from an infected mother to the fetus. Toxoplasmosis can only be transmitted to a fetus during maternal parastemia. Congenital toxoplasmosis accounts for the majority of cases encountered in clinical practice.
In most cases, the body is primed for infection or toxoplasmosis reactivation by an immune system failure. This may occur following contraction of human immunodeficiency syndrome (HIV) or with medical immunosupression following organ transplantation.
The inflammatory fundus lesions are composed of mononuclear cells, with a liberation of lymphocytes, macrophages, epithelioid and plasma cells. The resulting retinal vasculitis contributes to the breakdown of the blood-retinal barrier and leads to a compromise in retinal function, with subsequent destruction and thickening.
MANAGEMENT
The goal of management is twofold: (1) eradicate the parasite and (2) suppress the inflammatory response. The classic treatment regimen combines pyrimethamine (a 75mg loading dose, followed by 25mg PO BID administration) with sulfadiazine (2g loading dose, then 1g PO QID for 4 to 6 weeks). Both medications inhibit the folic acid metabolism necessary for toxoplasmosis to survive. Concurrent folinic acid, 3 to 5mg PO twice weekly helps to minimize any bone marrow toxicity produced by the pyramethamine.
Alternative antibiotic treatments include: (1) clindamycin, 300mg, PO QID used with sulfadiazine, for four to six weeks, (2) tetracycline, 2g loading then 250mg PO QID and sulfadiazine for four to six weeks, or (3) trimethoprim/sulfamethoxazole 160/800mg, one tablet PO BID, with or without clindamycin or prednisone, for the same duration.
In otherwise normal individuals, after beginning antibiotic therapy, add oral steroids at a dose of 20 to 80mg PO daily for four to six weeks. Periocular steroids are never indicated. Oral steroids without systemic antibiotics are expressly contraindicated.
Manage the anterior ocular inflammation with a cycloplegic that is appropriate for the disease's severity and a topical steroid Q2H/QID.
Systemic laboratory testing is indicated in active cases. The Sabin-Feldman methylene blue dye test (for Toxoplasma gondii), Serum antitoxoplasma antibody titer (for Toxoplasma gondii), Fluorescent Treponemal Antibody absorption test (for syphilis), purified protein derivative (for tuberculosis), chest x-ray (for sarcoid and TB), Toxocara Enzyme Linked Immunofluorescent Assay (for Toxocara canis) and Human Immunodefeciency Virus titer (for HIV) are among the important tests to order.
CLINICAL PEARLS
Since the organism may remain viable for up to 25 years and reactivation attacks are common, patient education is vital. If an outbreak is discovered in a community, provide education regarding the consumption of uncooked or under-cooked foods and the danger of untidy cats and/or their litter boxes.
In patients who have active infection, consider HIV/AIDS, especially if no other obvious means of immunosuppression are present. Surgical modalities, such as laser photocoagulation and cryopexy, have less value and are traditionally only recommended when the other modalities have failed.
Friday, November 4, 2011
RETINAL ARTERY OCCLUSION
SIGNS AND SYMPTOMS
The patient, usually between the ages of 50 and 80, will present with a sudden, painless, unilateral loss of vision and/or visual field. Acuity may be as low as hand motion. The patient often has significant systemic illness such as hypertension and/or diabetes. There will be a relative afferent pupillary defect in the involved eye.
Ophthalmoscopically, you'll see a pale, milky, edematous retina with attenuated arterioles and a cherry-red macula if the entire central retinal artery is occluded. If a cilioretinal artery is present, there will be an area of perfusion from the optic disc to the macula. An embolus may be visible in the vasculature on the disc. If a branch retinal artery is involved, an embolus will be visible in the vessel with ischemia and infarct appearing distal to the occlusion.
PATHOPHYSIOLOGY
The main cause of retinal arterial occlusions is an embolism lodging in the central retinal artery where it constricts to pass through the lamina cribrosa, or in a smaller branch arteriole. The embolism may be comprised of aggregated fibrin and platelets arising from an ulcerated vessel wall thrombus, cholesterol from an ulcerated carotid artery plaque, or calcium from cardiac valvular disease.
Abnormal cardiac rhythms may allow blood to coagulate and form emboli which may also reach the retinal vasculature. Neovascularization is not common with either central or branch artery occlusions, but if it does occur, it will do so rapidly, with rubeosis forming approximately four weeks after the occlusion. Between two and 10 percent of central retinal artery occlusions are caused by thrombus formation from giant cell arteritis (GCA). If the underlying cause of the central retinal artery occlusion is GCA, there may be a rapid progression to bilateral vision loss if left untreated.
MANAGEMENT
Traditionally, central retinal artery occlusion has been considered an emergency. It was felt that, if the embolus could be dislodged within 90 minutes of occlusion, vision could be potentially salvaged with the retina being re-perfused. To this end, various methods have been employed to reduce resistance on the artery or dilate the artery to induce the embolus to dislodge.
Common methods employed included breathing into a paper bag to increase blood carbon dioxide levels and induce vasodilation, digital globe massage, paracentesis, and carbonic anhydrase inhibitors to reduce intraocular pressure and decrease vascular resistance to flow. Most practitioners would attempt these measures if the occlusion were less than 24 hours old. While there is anecdotal evidence that these measures have sporadically resulted in vision returning, a large study showed that the average final visual outcome in patients with embolic central retinal artery occlusion treated with heroic measures compared to those untreated was only one-quarter line improvement in Snellen acuity.
Patients with arterial occlusion have significant systemic illness, namely hypertension, atherosclerosis or diabetes. These patients are at extreme risk for cardiovascular disease and myocardial infarction. For this reason, these patients need prompt referral to a cardiologist for complete evaluation. Medical testing should include blood pressure evaluation, EKG, fasting blood glucose, lipid and cholesterol levels, and hyperviscosity studies. Patients with central retinal artery occlusion over the age of 60 need an immediate erythrocyte sedimentation rate (ESR) to examine for the possibility of giant cell arteritis. Fluorescein angiography is generally not indicated.
CLINICAL PEARLS
Traditional heroic measures to salvage vision generally do not produce significant changes in the patient's vision.
These patients have a significantly reduced survival rate, and the main cause of mortality is cardiac. Therefore, prompt referral to a cardiologist is indicated.
Central retinal artery occlusion may be caused by GCA; if undetected, the patient can develop severe, bilateral vision loss.
The patient, usually between the ages of 50 and 80, will present with a sudden, painless, unilateral loss of vision and/or visual field. Acuity may be as low as hand motion. The patient often has significant systemic illness such as hypertension and/or diabetes. There will be a relative afferent pupillary defect in the involved eye.
Ophthalmoscopically, you'll see a pale, milky, edematous retina with attenuated arterioles and a cherry-red macula if the entire central retinal artery is occluded. If a cilioretinal artery is present, there will be an area of perfusion from the optic disc to the macula. An embolus may be visible in the vasculature on the disc. If a branch retinal artery is involved, an embolus will be visible in the vessel with ischemia and infarct appearing distal to the occlusion.
PATHOPHYSIOLOGY
The main cause of retinal arterial occlusions is an embolism lodging in the central retinal artery where it constricts to pass through the lamina cribrosa, or in a smaller branch arteriole. The embolism may be comprised of aggregated fibrin and platelets arising from an ulcerated vessel wall thrombus, cholesterol from an ulcerated carotid artery plaque, or calcium from cardiac valvular disease.
Abnormal cardiac rhythms may allow blood to coagulate and form emboli which may also reach the retinal vasculature. Neovascularization is not common with either central or branch artery occlusions, but if it does occur, it will do so rapidly, with rubeosis forming approximately four weeks after the occlusion. Between two and 10 percent of central retinal artery occlusions are caused by thrombus formation from giant cell arteritis (GCA). If the underlying cause of the central retinal artery occlusion is GCA, there may be a rapid progression to bilateral vision loss if left untreated.
MANAGEMENT
Traditionally, central retinal artery occlusion has been considered an emergency. It was felt that, if the embolus could be dislodged within 90 minutes of occlusion, vision could be potentially salvaged with the retina being re-perfused. To this end, various methods have been employed to reduce resistance on the artery or dilate the artery to induce the embolus to dislodge.
Common methods employed included breathing into a paper bag to increase blood carbon dioxide levels and induce vasodilation, digital globe massage, paracentesis, and carbonic anhydrase inhibitors to reduce intraocular pressure and decrease vascular resistance to flow. Most practitioners would attempt these measures if the occlusion were less than 24 hours old. While there is anecdotal evidence that these measures have sporadically resulted in vision returning, a large study showed that the average final visual outcome in patients with embolic central retinal artery occlusion treated with heroic measures compared to those untreated was only one-quarter line improvement in Snellen acuity.
Patients with arterial occlusion have significant systemic illness, namely hypertension, atherosclerosis or diabetes. These patients are at extreme risk for cardiovascular disease and myocardial infarction. For this reason, these patients need prompt referral to a cardiologist for complete evaluation. Medical testing should include blood pressure evaluation, EKG, fasting blood glucose, lipid and cholesterol levels, and hyperviscosity studies. Patients with central retinal artery occlusion over the age of 60 need an immediate erythrocyte sedimentation rate (ESR) to examine for the possibility of giant cell arteritis. Fluorescein angiography is generally not indicated.
CLINICAL PEARLS
Traditional heroic measures to salvage vision generally do not produce significant changes in the patient's vision.
These patients have a significantly reduced survival rate, and the main cause of mortality is cardiac. Therefore, prompt referral to a cardiologist is indicated.
Central retinal artery occlusion may be caused by GCA; if undetected, the patient can develop severe, bilateral vision loss.
RETINAL VEIN OCCLUSION
SIGNS AND SYMPTOMS
The patient will usually be elderly, often with a history of systemic diseases such as diabetes and hypertension. The patient may be asymptomatic, but often will complain of sudden painless unilateral loss of vision and/or visual field, and may complain of a sudden onset of floating spots or flashing lights. Acuity may range anywhere from 20/20 to finger counting. If vision loss is severe, there may be a relative afferent pupillary defect.
Ophthalmoscopically, there will be retinal edema, superficial hemorrhages, disc swelling, cotton wool spots, and tortuous and dilated retinal veins. If there is a central retinal vein occlusion, these findings will encompass all four retinal quadrants. A hemi-central retinal vein occlusion will involve only the superior or inferior half of the retina. A branch retinal vein occlusion will present with findings in only one quadrant, usually supero-temporal, with the apex of the hemorrhage at an arteriovenous crossing.
The hemorrhaging may be so severe that all features of the underlying retina are obscured. Multiple cotton wool spots indicate retinal ischemia and capillary non-perfusion. Anterior and posterior segment neovascularization may occur later in the disease.
PATHOPHYSIOLOGY
The etiology of central and hemi-central retinal vein occlusion is an obstruction of the central retinal vein, or one of the vein's two trunks, as it constricts through the lamina cribrosa. The cause is obscure, but may involve abnormal blood flow or blood constituents, atherosclerosis, vessel anomalies or a combination of these factors.
The etiology of a branch retinal vein occlusion is an arteriolosclerotic arteriole crossing and constricting the underlying venule. This will result in leakage from the capillary beds draining into these vessels. The capillary beds may be irreversibly damaged by this leakage, resulting in perpetual non-perfusion of the retinal tissue. If a significant area of capillary non-perfusion is present, then the occlusion is considered ischemic.
Loss of retinal capillary beds with subsequent retinal non-perfusion will lead to retinal hypoxia and the subsequent release of vasoproliferative substance. Vasoproliferative factors will then stimulate the proliferation of neovascularization from nearby viable capillary beds.
In branch and hemi-central occlusions, neovascularization will most often form on the optic disc or adjacent retina and can lead to vitreous hemorrhage and tractional retinal detachment. In central retinal vein occlusions, the closest viable capillary network from which neovascularization will form is typically the posterior iris. This can lead to rubeosis irides and neovascular glaucoma. In all cases of venous occlusion, the main cause of vision decrease is macular edema. However, if retinal capillary non-perfusion involves the perifoveal region, then vision is dramatically and irreversibly lost.
MANAGEMENT
Fluorescein angiography, long held to be the gold standard in assessing retinal vascular disease, has questionable use in vein occlusions. It is not indicated initially, as the fresh hemorrhage will block transmission and reveal no useful information, but later in the disease it will provide information about retinal capillary perfusion and whether or not the occlusion is ischemic and thus more likely to foster neovascularization. New research indicates that ischemic retinal vein occlusions do not benefit from prophylactic PRP; withhold this procedure until the patient develops frank neovascularization of the iris, disc or retina.
Monitor the patient monthly with serial ophthalmoscopy, fundus photography and goniscopy until you see resolution. If the patient has a hemi-central or branch retinal vein occlusion and vision is below 20/40 due to macular edema, the patient will benefit from focal laser photocoagulation anywhere between three and 18 months after the occlusion's onset. Central retinal vein occlusion patients with vision reduction due to macular edema do not benefit from the proceudre, according to new research.
Due to the association of systemic disease with vein occlusions, co-manage the patient with an internist. Tests to be ordered include: blood pressure, fasting blood glucose, lipid and cholesterol studies, FTA-ABS, complete blood count with differential, sickle dex (if the patient is African-American), anti-nuclear antibodies, angiotensin converting enzymes, and viscosity studies.
CLINICAL PEARLS
Ischemic vein occlusions are the only vein occlusions that will likely develop neovascular complications, and they account for only one-third of all occlusions.
Ischemic vein occlusions typically present with acuity worse than 20/200. Those eyes with initial acuity better than 20/200 are at very low risk of developing severe, permanent vision loss, and are likely to resolve.
Ischemic occlusions are likely to present with a relative afferent pupillary defect. If not, then it is likely non-ischemic.
The patient will usually be elderly, often with a history of systemic diseases such as diabetes and hypertension. The patient may be asymptomatic, but often will complain of sudden painless unilateral loss of vision and/or visual field, and may complain of a sudden onset of floating spots or flashing lights. Acuity may range anywhere from 20/20 to finger counting. If vision loss is severe, there may be a relative afferent pupillary defect.
Ophthalmoscopically, there will be retinal edema, superficial hemorrhages, disc swelling, cotton wool spots, and tortuous and dilated retinal veins. If there is a central retinal vein occlusion, these findings will encompass all four retinal quadrants. A hemi-central retinal vein occlusion will involve only the superior or inferior half of the retina. A branch retinal vein occlusion will present with findings in only one quadrant, usually supero-temporal, with the apex of the hemorrhage at an arteriovenous crossing.
The hemorrhaging may be so severe that all features of the underlying retina are obscured. Multiple cotton wool spots indicate retinal ischemia and capillary non-perfusion. Anterior and posterior segment neovascularization may occur later in the disease.
PATHOPHYSIOLOGY
The etiology of central and hemi-central retinal vein occlusion is an obstruction of the central retinal vein, or one of the vein's two trunks, as it constricts through the lamina cribrosa. The cause is obscure, but may involve abnormal blood flow or blood constituents, atherosclerosis, vessel anomalies or a combination of these factors.
The etiology of a branch retinal vein occlusion is an arteriolosclerotic arteriole crossing and constricting the underlying venule. This will result in leakage from the capillary beds draining into these vessels. The capillary beds may be irreversibly damaged by this leakage, resulting in perpetual non-perfusion of the retinal tissue. If a significant area of capillary non-perfusion is present, then the occlusion is considered ischemic.
Loss of retinal capillary beds with subsequent retinal non-perfusion will lead to retinal hypoxia and the subsequent release of vasoproliferative substance. Vasoproliferative factors will then stimulate the proliferation of neovascularization from nearby viable capillary beds.
In branch and hemi-central occlusions, neovascularization will most often form on the optic disc or adjacent retina and can lead to vitreous hemorrhage and tractional retinal detachment. In central retinal vein occlusions, the closest viable capillary network from which neovascularization will form is typically the posterior iris. This can lead to rubeosis irides and neovascular glaucoma. In all cases of venous occlusion, the main cause of vision decrease is macular edema. However, if retinal capillary non-perfusion involves the perifoveal region, then vision is dramatically and irreversibly lost.
MANAGEMENT
Fluorescein angiography, long held to be the gold standard in assessing retinal vascular disease, has questionable use in vein occlusions. It is not indicated initially, as the fresh hemorrhage will block transmission and reveal no useful information, but later in the disease it will provide information about retinal capillary perfusion and whether or not the occlusion is ischemic and thus more likely to foster neovascularization. New research indicates that ischemic retinal vein occlusions do not benefit from prophylactic PRP; withhold this procedure until the patient develops frank neovascularization of the iris, disc or retina.
Monitor the patient monthly with serial ophthalmoscopy, fundus photography and goniscopy until you see resolution. If the patient has a hemi-central or branch retinal vein occlusion and vision is below 20/40 due to macular edema, the patient will benefit from focal laser photocoagulation anywhere between three and 18 months after the occlusion's onset. Central retinal vein occlusion patients with vision reduction due to macular edema do not benefit from the proceudre, according to new research.
Due to the association of systemic disease with vein occlusions, co-manage the patient with an internist. Tests to be ordered include: blood pressure, fasting blood glucose, lipid and cholesterol studies, FTA-ABS, complete blood count with differential, sickle dex (if the patient is African-American), anti-nuclear antibodies, angiotensin converting enzymes, and viscosity studies.
CLINICAL PEARLS
Ischemic vein occlusions are the only vein occlusions that will likely develop neovascular complications, and they account for only one-third of all occlusions.
Ischemic vein occlusions typically present with acuity worse than 20/200. Those eyes with initial acuity better than 20/200 are at very low risk of developing severe, permanent vision loss, and are likely to resolve.
Ischemic occlusions are likely to present with a relative afferent pupillary defect. If not, then it is likely non-ischemic.
RETINAL VEIN OCCLUSION
SIGNS AND SYMPTOMS
The patient will usually be elderly, often with a history of systemic diseases such as diabetes and hypertension. The patient may be asymptomatic, but often will complain of sudden painless unilateral loss of vision and/or visual field, and may complain of a sudden onset of floating spots or flashing lights. Acuity may range anywhere from 20/20 to finger counting. If vision loss is severe, there may be a relative afferent pupillary defect.
Ophthalmoscopically, there will be retinal edema, superficial hemorrhages, disc swelling, cotton wool spots, and tortuous and dilated retinal veins. If there is a central retinal vein occlusion, these findings will encompass all four retinal quadrants. A hemi-central retinal vein occlusion will involve only the superior or inferior half of the retina. A branch retinal vein occlusion will present with findings in only one quadrant, usually supero-temporal, with the apex of the hemorrhage at an arteriovenous crossing.
The hemorrhaging may be so severe that all features of the underlying retina are obscured. Multiple cotton wool spots indicate retinal ischemia and capillary non-perfusion. Anterior and posterior segment neovascularization may occur later in the disease.
PATHOPHYSIOLOGY
The etiology of central and hemi-central retinal vein occlusion is an obstruction of the central retinal vein, or one of the vein's two trunks, as it constricts through the lamina cribrosa. The cause is obscure, but may involve abnormal blood flow or blood constituents, atherosclerosis, vessel anomalies or a combination of these factors.
The etiology of a branch retinal vein occlusion is an arteriolosclerotic arteriole crossing and constricting the underlying venule. This will result in leakage from the capillary beds draining into these vessels. The capillary beds may be irreversibly damaged by this leakage, resulting in perpetual non-perfusion of the retinal tissue. If a significant area of capillary non-perfusion is present, then the occlusion is considered ischemic.
Loss of retinal capillary beds with subsequent retinal non-perfusion will lead to retinal hypoxia and the subsequent release of vasoproliferative substance. Vasoproliferative factors will then stimulate the proliferation of neovascularization from nearby viable capillary beds.
In branch and hemi-central occlusions, neovascularization will most often form on the optic disc or adjacent retina and can lead to vitreous hemorrhage and tractional retinal detachment. In central retinal vein occlusions, the closest viable capillary network from which neovascularization will form is typically the posterior iris. This can lead to rubeosis irides and neovascular glaucoma. In all cases of venous occlusion, the main cause of vision decrease is macular edema. However, if retinal capillary non-perfusion involves the perifoveal region, then vision is dramatically and irreversibly lost.
MANAGEMENT
Fluorescein angiography, long held to be the gold standard in assessing retinal vascular disease, has questionable use in vein occlusions. It is not indicated initially, as the fresh hemorrhage will block transmission and reveal no useful information, but later in the disease it will provide information about retinal capillary perfusion and whether or not the occlusion is ischemic and thus more likely to foster neovascularization. New research indicates that ischemic retinal vein occlusions do not benefit from prophylactic PRP; withhold this procedure until the patient develops frank neovascularization of the iris, disc or retina.
Monitor the patient monthly with serial ophthalmoscopy, fundus photography and goniscopy until you see resolution. If the patient has a hemi-central or branch retinal vein occlusion and vision is below 20/40 due to macular edema, the patient will benefit from focal laser photocoagulation anywhere between three and 18 months after the occlusion's onset. Central retinal vein occlusion patients with vision reduction due to macular edema do not benefit from the proceudre, according to new research.
Due to the association of systemic disease with vein occlusions, co-manage the patient with an internist. Tests to be ordered include: blood pressure, fasting blood glucose, lipid and cholesterol studies, FTA-ABS, complete blood count with differential, sickle dex (if the patient is African-American), anti-nuclear antibodies, angiotensin converting enzymes, and viscosity studies.
CLINICAL PEARLS
Ischemic vein occlusions are the only vein occlusions that will likely develop neovascular complications, and they account for only one-third of all occlusions.
Ischemic vein occlusions typically present with acuity worse than 20/200. Those eyes with initial acuity better than 20/200 are at very low risk of developing severe, permanent vision loss, and are likely to resolve.
Ischemic occlusions are likely to present with a relative afferent pupillary defect. If not, then it is likely non-ischemic.
The patient will usually be elderly, often with a history of systemic diseases such as diabetes and hypertension. The patient may be asymptomatic, but often will complain of sudden painless unilateral loss of vision and/or visual field, and may complain of a sudden onset of floating spots or flashing lights. Acuity may range anywhere from 20/20 to finger counting. If vision loss is severe, there may be a relative afferent pupillary defect.
Ophthalmoscopically, there will be retinal edema, superficial hemorrhages, disc swelling, cotton wool spots, and tortuous and dilated retinal veins. If there is a central retinal vein occlusion, these findings will encompass all four retinal quadrants. A hemi-central retinal vein occlusion will involve only the superior or inferior half of the retina. A branch retinal vein occlusion will present with findings in only one quadrant, usually supero-temporal, with the apex of the hemorrhage at an arteriovenous crossing.
The hemorrhaging may be so severe that all features of the underlying retina are obscured. Multiple cotton wool spots indicate retinal ischemia and capillary non-perfusion. Anterior and posterior segment neovascularization may occur later in the disease.
PATHOPHYSIOLOGY
The etiology of central and hemi-central retinal vein occlusion is an obstruction of the central retinal vein, or one of the vein's two trunks, as it constricts through the lamina cribrosa. The cause is obscure, but may involve abnormal blood flow or blood constituents, atherosclerosis, vessel anomalies or a combination of these factors.
The etiology of a branch retinal vein occlusion is an arteriolosclerotic arteriole crossing and constricting the underlying venule. This will result in leakage from the capillary beds draining into these vessels. The capillary beds may be irreversibly damaged by this leakage, resulting in perpetual non-perfusion of the retinal tissue. If a significant area of capillary non-perfusion is present, then the occlusion is considered ischemic.
Loss of retinal capillary beds with subsequent retinal non-perfusion will lead to retinal hypoxia and the subsequent release of vasoproliferative substance. Vasoproliferative factors will then stimulate the proliferation of neovascularization from nearby viable capillary beds.
In branch and hemi-central occlusions, neovascularization will most often form on the optic disc or adjacent retina and can lead to vitreous hemorrhage and tractional retinal detachment. In central retinal vein occlusions, the closest viable capillary network from which neovascularization will form is typically the posterior iris. This can lead to rubeosis irides and neovascular glaucoma. In all cases of venous occlusion, the main cause of vision decrease is macular edema. However, if retinal capillary non-perfusion involves the perifoveal region, then vision is dramatically and irreversibly lost.
MANAGEMENT
Fluorescein angiography, long held to be the gold standard in assessing retinal vascular disease, has questionable use in vein occlusions. It is not indicated initially, as the fresh hemorrhage will block transmission and reveal no useful information, but later in the disease it will provide information about retinal capillary perfusion and whether or not the occlusion is ischemic and thus more likely to foster neovascularization. New research indicates that ischemic retinal vein occlusions do not benefit from prophylactic PRP; withhold this procedure until the patient develops frank neovascularization of the iris, disc or retina.
Monitor the patient monthly with serial ophthalmoscopy, fundus photography and goniscopy until you see resolution. If the patient has a hemi-central or branch retinal vein occlusion and vision is below 20/40 due to macular edema, the patient will benefit from focal laser photocoagulation anywhere between three and 18 months after the occlusion's onset. Central retinal vein occlusion patients with vision reduction due to macular edema do not benefit from the proceudre, according to new research.
Due to the association of systemic disease with vein occlusions, co-manage the patient with an internist. Tests to be ordered include: blood pressure, fasting blood glucose, lipid and cholesterol studies, FTA-ABS, complete blood count with differential, sickle dex (if the patient is African-American), anti-nuclear antibodies, angiotensin converting enzymes, and viscosity studies.
CLINICAL PEARLS
Ischemic vein occlusions are the only vein occlusions that will likely develop neovascular complications, and they account for only one-third of all occlusions.
Ischemic vein occlusions typically present with acuity worse than 20/200. Those eyes with initial acuity better than 20/200 are at very low risk of developing severe, permanent vision loss, and are likely to resolve.
Ischemic occlusions are likely to present with a relative afferent pupillary defect. If not, then it is likely non-ischemic.
SIGNS AND SYMPTOMS
The patient is usually over age 20 and is nearly always asymptomatic, except for possible complaints of flashing lights (photopsia). There appears to be a higher incidence of myopia in patients with lattice degeneration. There is no racial or sexual predilection.
Lattice degeneration occurs in eight to 11 percent of the general population. It presents as a linear trail of fibrosed vessels within atrophied retina in a "lattice" pattern. It nearly always runs circumferentially between the equator and the ora serrata. The individual lesions are usually from one-half to six disc diameters and may run 360 degrees around the eye in a discontinuous pattern. There may be associated RPE hyperplasia, giving the lesion a pigmented appearance. Atrophic holes are often present in the lesion, occasionally large enough to encompass the entire lattice lesion. The incidence of atrophic holes in lattice degeneration ranges from 18 to 42 percent. A tractional linear tear will occur on the posterior edge of lattice lesions in 1.9 percent of lesions. Lattice degeneration is typically bilateral.
PATHOPHYSIOLOGY
The etiology of lattice is questionable. It appears to be due to dropout of peripheral retinal capillaries with resulting ischemia, which induces thinning of all retinal layers. There is sclerosis of the larger vessels, with their lumen being filled with extracellular glial tissue, giving lattice degeneration its characteristic fibrotic appearance.
The retinal thinning has several effects: (1) the overlying vitreous will be disturbed, resulting in a pocket of liquefaction overlying the lattice lesion known as a lacuna; (2) the vitreous along the edges of the lattice lesion will undergo strong adhesion to the retina; and (3) the ischemia and retinal thinning will disturb the retinal pigment epithelium, resulting in RPE hyperplasia and a pigmented appearance.
Often the thinning becomes so profound that a full-thickness hole atrophies through the retina at the lattice lesion. The overlying liquefied vitreous has the ability to pass through the hole into the subretinal space and possibly lead to rhegmatogenous retinal detachment. This will occur in approximately two percent of cases of holes within lattice degeneration. Due to the liquefaction of the overlying vitreous, there is no vitreoretinal traction on the edges of a hole in lattice degeneration. If a posterior vitreous detachment occurs, the vitreoretinal traction along the posterior edge of a lattice lesion may result in a linear tear, with an ensuing progression to rhegmatogenous retinal detachment in 37 percent of cases.
MANAGEMENT
The main concern with lattice degeneration is the chance of progression to rhegmatogenous retinal detachment. With many types of retinal breaks, the area is often prophylactically sealed with laser photocoagulation or cryoretinopexy to prevent this. In lattice degeneration alone, prophylactic treatment is not practical in that the risk of detachment is only 0.1 to 0.7 percent in the phakic eye. Atrophic holes in phakic eyes with lattice degeneration also do not require prophylactic treatment, as the risk of progression to detachment is two percent or less.
Furthermore, prophylactic treatment of lattice lesions in eyes with greater than 6.00D of myopia yields no benefit. These lesions need only routine, yearly monitoring with the patient educated about signs and symptoms of retinal detachment. However, a linear tractional tear forming at the posterior border of a lattice lesion has about a 37 percent risk of progression to retinal detachment and therefore should receive prophylactic therapy.
CLINICAL PEARLS
Lattice degeneration both with and without atrophic holes is generally benign and does not require prophylactic treatment, as the complications of treatment are more severe than the natural history of the untreated condition.
The ominous tractional tear at the posterior border of a lattice lesion is very difficult to see ophthalmoscopically. These tears will usually only become apparent upon scleral indentation. Perform scleral indentation, whenever possible, on every lattice lesion to look for an occult tractional tear.
The patient is usually over age 20 and is nearly always asymptomatic, except for possible complaints of flashing lights (photopsia). There appears to be a higher incidence of myopia in patients with lattice degeneration. There is no racial or sexual predilection.
Lattice degeneration occurs in eight to 11 percent of the general population. It presents as a linear trail of fibrosed vessels within atrophied retina in a "lattice" pattern. It nearly always runs circumferentially between the equator and the ora serrata. The individual lesions are usually from one-half to six disc diameters and may run 360 degrees around the eye in a discontinuous pattern. There may be associated RPE hyperplasia, giving the lesion a pigmented appearance. Atrophic holes are often present in the lesion, occasionally large enough to encompass the entire lattice lesion. The incidence of atrophic holes in lattice degeneration ranges from 18 to 42 percent. A tractional linear tear will occur on the posterior edge of lattice lesions in 1.9 percent of lesions. Lattice degeneration is typically bilateral.
PATHOPHYSIOLOGY
The etiology of lattice is questionable. It appears to be due to dropout of peripheral retinal capillaries with resulting ischemia, which induces thinning of all retinal layers. There is sclerosis of the larger vessels, with their lumen being filled with extracellular glial tissue, giving lattice degeneration its characteristic fibrotic appearance.
The retinal thinning has several effects: (1) the overlying vitreous will be disturbed, resulting in a pocket of liquefaction overlying the lattice lesion known as a lacuna; (2) the vitreous along the edges of the lattice lesion will undergo strong adhesion to the retina; and (3) the ischemia and retinal thinning will disturb the retinal pigment epithelium, resulting in RPE hyperplasia and a pigmented appearance.
Often the thinning becomes so profound that a full-thickness hole atrophies through the retina at the lattice lesion. The overlying liquefied vitreous has the ability to pass through the hole into the subretinal space and possibly lead to rhegmatogenous retinal detachment. This will occur in approximately two percent of cases of holes within lattice degeneration. Due to the liquefaction of the overlying vitreous, there is no vitreoretinal traction on the edges of a hole in lattice degeneration. If a posterior vitreous detachment occurs, the vitreoretinal traction along the posterior edge of a lattice lesion may result in a linear tear, with an ensuing progression to rhegmatogenous retinal detachment in 37 percent of cases.
MANAGEMENT
The main concern with lattice degeneration is the chance of progression to rhegmatogenous retinal detachment. With many types of retinal breaks, the area is often prophylactically sealed with laser photocoagulation or cryoretinopexy to prevent this. In lattice degeneration alone, prophylactic treatment is not practical in that the risk of detachment is only 0.1 to 0.7 percent in the phakic eye. Atrophic holes in phakic eyes with lattice degeneration also do not require prophylactic treatment, as the risk of progression to detachment is two percent or less.
Furthermore, prophylactic treatment of lattice lesions in eyes with greater than 6.00D of myopia yields no benefit. These lesions need only routine, yearly monitoring with the patient educated about signs and symptoms of retinal detachment. However, a linear tractional tear forming at the posterior border of a lattice lesion has about a 37 percent risk of progression to retinal detachment and therefore should receive prophylactic therapy.
CLINICAL PEARLS
Lattice degeneration both with and without atrophic holes is generally benign and does not require prophylactic treatment, as the complications of treatment are more severe than the natural history of the untreated condition.
The ominous tractional tear at the posterior border of a lattice lesion is very difficult to see ophthalmoscopically. These tears will usually only become apparent upon scleral indentation. Perform scleral indentation, whenever possible, on every lattice lesion to look for an occult tractional tear.
DIABETIC RETINOPATHY
SIGNS AND SYMPTOMS
A microvascular disease that primarily affects the capillaries, diabetes mellitus affects the eye by destroying the vasculature in the conjunctiva, retina and central nervous system. Patients may present with histories of long-standing injected bulbar conjunctivae along with systemic complaints of weight loss despite larger than normal appetite (polyphasia), abnormal thirst (polydypsia) and abnormally frequent urination (polyuria).
Fluctuating visual acuity secondary to unstable blood sugar is a common ocular sign. Swelling within the crystalline lens results in large sudden shifts in refraction as well as premature cataract formation. Changes in visual acuity will depend upon the severity and stage of the disease.
In the retina, weakening of the arterioles and capillaries may result in the characteristic appearance of intraretinal dot and blot hemorrhages, exudates, intraretinal microvascular abnormalities (IRMA) microaneurysms, edema and cotton wool infarcts. Proliferative diabetic retinopathy is the result of severe vascular compromise and is visible as neovascularization of the disc (NVD), neovascularization elsewhere (NVE) and neovascularization of the iris (NVI, or rubeosis irides). Neurological complications include palsies of the third, fourth and sixth cranial nerves as well as diabetic papillitis and facial nerve paralysis.
PATHOPHYSIOLOGY
Diabetes mellitus is a genetically influenced group of diseases that share glucose intolerance. It is characterized as a disorder of metabolic regulation as a result of deficient or malfunctioning insulin or deficient or malfunctioning cellular insulin receptors.
Biochemistry involving the formation of sorbitol plays a role in the destruction of pericytes, which are cells that support the vascular endothelium. As the supportive pericytes perish, capillary endothelium becomes compromised, resulting in the vascular leakage of blood, protein and lipid. This, in combination with thickened, glucose-laden blood, produces vascular insufficiency, capillary nonperfusion, retinal hypoxia, altered structure and decreased function. The formation and release of vasoproliferative factors which play a role in the genesis of retinal neovascularization are poorly understood.
MANAGEMENT
When you suspect ocular sequelae of diabetes mellitus in an undiagnosed individual, either you or the patient's physician should order a fasting blood glucose (FBS), glycosylated hemoglobin or oral glucose tolerance test (OGTT).
Most non-vision threatening sequelae of diabetes resolve spontaneously over the course of weeks to months following medical control. In cases where there are large refractive changes, patients may require a temporary spectacle prescription until the refraction stabilizes. The most important element of
MANAGEMENT is education so that patients are informed that they may eventually need to change their spectacle lenses.
When retinopathy threatens the macula or when new blood vessels proliferate, refer for laser photocoagulation. The Diabetic Retinopathy Study (DRS) has conclusively proven that panretinal photocoagulation was successful in reducing the risk of severe vision loss in high risk patients. It defined the high risk characteristics as: (1) Neovascularization of the optic disc (NVD) one-quarter to one-third of a disc diameter in size and (2) Neovascularization elsewhere (NVE) with any vitreous hemorrhage.
If the patient exhibits either of these high risk characteristics, refer him or her to a vitreoretinal specialist.
The Early Treatment of Diabetic Retinopathy Study (ETDRS) has shown that focal/grid laser photocoagulation reduced the risk of moderate vision loss in patients with clinically significant macular edema, defined as: (1) retinal thickening at or within 500 microns (one-third of a disc diameter) of the center of the foveola, (2) exudate at or within 500 microns of the center of the foveola only if associated with retinal thickening, or (3) an area of retinal thickening one disc diameter or greater in size, within one disc diameter of the foveola.
If you observe any of these signs, regardless of the acuity, refer the patient to a retinal specialist. Referral is also indicated if you suspect clinically significant macular edema but are having difficulty visualizing the macula or edema.
CLINICAL PEARLS
Clinically significant macular edema is unrelated to acuity and can exist in the presence of 20/20 vision. It can only be identified through observation using stereoscopic indirect biomicroscopy (60D, 78D, 90D Hruby or three-mirror lens).
Fluorescein angiography is only used for treatment. It identifies the areas of leakage that require focal grid laser photocoagulation. With respect to diabetes, it is not a tool for diagnosis. Angiography is not required for treating proliferative disease since PRP does not require precise aiming of the laser.
The development of diabetic retinopathy is time-dependent. Even in the face of optimal blood sugar control, patients with long-standing disease can be expected to eventually develop some form of retinopathy.
A microvascular disease that primarily affects the capillaries, diabetes mellitus affects the eye by destroying the vasculature in the conjunctiva, retina and central nervous system. Patients may present with histories of long-standing injected bulbar conjunctivae along with systemic complaints of weight loss despite larger than normal appetite (polyphasia), abnormal thirst (polydypsia) and abnormally frequent urination (polyuria).
Fluctuating visual acuity secondary to unstable blood sugar is a common ocular sign. Swelling within the crystalline lens results in large sudden shifts in refraction as well as premature cataract formation. Changes in visual acuity will depend upon the severity and stage of the disease.
In the retina, weakening of the arterioles and capillaries may result in the characteristic appearance of intraretinal dot and blot hemorrhages, exudates, intraretinal microvascular abnormalities (IRMA) microaneurysms, edema and cotton wool infarcts. Proliferative diabetic retinopathy is the result of severe vascular compromise and is visible as neovascularization of the disc (NVD), neovascularization elsewhere (NVE) and neovascularization of the iris (NVI, or rubeosis irides). Neurological complications include palsies of the third, fourth and sixth cranial nerves as well as diabetic papillitis and facial nerve paralysis.
PATHOPHYSIOLOGY
Diabetes mellitus is a genetically influenced group of diseases that share glucose intolerance. It is characterized as a disorder of metabolic regulation as a result of deficient or malfunctioning insulin or deficient or malfunctioning cellular insulin receptors.
Biochemistry involving the formation of sorbitol plays a role in the destruction of pericytes, which are cells that support the vascular endothelium. As the supportive pericytes perish, capillary endothelium becomes compromised, resulting in the vascular leakage of blood, protein and lipid. This, in combination with thickened, glucose-laden blood, produces vascular insufficiency, capillary nonperfusion, retinal hypoxia, altered structure and decreased function. The formation and release of vasoproliferative factors which play a role in the genesis of retinal neovascularization are poorly understood.
MANAGEMENT
When you suspect ocular sequelae of diabetes mellitus in an undiagnosed individual, either you or the patient's physician should order a fasting blood glucose (FBS), glycosylated hemoglobin or oral glucose tolerance test (OGTT).
Most non-vision threatening sequelae of diabetes resolve spontaneously over the course of weeks to months following medical control. In cases where there are large refractive changes, patients may require a temporary spectacle prescription until the refraction stabilizes. The most important element of
MANAGEMENT is education so that patients are informed that they may eventually need to change their spectacle lenses.
When retinopathy threatens the macula or when new blood vessels proliferate, refer for laser photocoagulation. The Diabetic Retinopathy Study (DRS) has conclusively proven that panretinal photocoagulation was successful in reducing the risk of severe vision loss in high risk patients. It defined the high risk characteristics as: (1) Neovascularization of the optic disc (NVD) one-quarter to one-third of a disc diameter in size and (2) Neovascularization elsewhere (NVE) with any vitreous hemorrhage.
If the patient exhibits either of these high risk characteristics, refer him or her to a vitreoretinal specialist.
The Early Treatment of Diabetic Retinopathy Study (ETDRS) has shown that focal/grid laser photocoagulation reduced the risk of moderate vision loss in patients with clinically significant macular edema, defined as: (1) retinal thickening at or within 500 microns (one-third of a disc diameter) of the center of the foveola, (2) exudate at or within 500 microns of the center of the foveola only if associated with retinal thickening, or (3) an area of retinal thickening one disc diameter or greater in size, within one disc diameter of the foveola.
If you observe any of these signs, regardless of the acuity, refer the patient to a retinal specialist. Referral is also indicated if you suspect clinically significant macular edema but are having difficulty visualizing the macula or edema.
CLINICAL PEARLS
Clinically significant macular edema is unrelated to acuity and can exist in the presence of 20/20 vision. It can only be identified through observation using stereoscopic indirect biomicroscopy (60D, 78D, 90D Hruby or three-mirror lens).
Fluorescein angiography is only used for treatment. It identifies the areas of leakage that require focal grid laser photocoagulation. With respect to diabetes, it is not a tool for diagnosis. Angiography is not required for treating proliferative disease since PRP does not require precise aiming of the laser.
The development of diabetic retinopathy is time-dependent. Even in the face of optimal blood sugar control, patients with long-standing disease can be expected to eventually develop some form of retinopathy.
TRACTIONAL RETINAL TEARS
SIGNS AND SYMPTOMS
The patient often will report a sudden onset of either a single or multiple floating spots, along with flashing lights (photopsia). Visual symptoms will be stable within the patient's visual field. There may be precipitating ocular or head trauma. If there is a posterior vitreous detachment, there will also be one large floater. If there has been a vitreous hemorrhage, there will be multiple floaters. There may be a severe loss of vision if there is a dense vitreous hemorrhage or rhegmatogenous retinal detachment. However, in a number of cases, the patient is either asymptomatic or experienced symptoms so long ago that they were forgotten.
PATHOPHYSIOLOGY
Retinal tears result from the vitreous pulling free from the retina during vitreous detachment. During the course of the PVD, the vitreous may encounter an area where it is firmly attached to the retina. These include the optic disc, macula, along blood vessels, vitreous base, at areas of chorioretinal scarring, along the edges of lattice degeneration, and at vitreoretinal tufts. Traction at any one of these points may result in the vitreous pulling the retina free from its loose attachment to the retinal pigment epithelium with a tear developing within the sensory retina. The subsequent break in the retina can allow liquid vitreous to enter the potential subretinal space, resulting in a rhegmatogenous retinal detachment. If the vitreous remains attached to the damaged retina, traction on the edges of the break can serve to further separate the retina from the RPE.
There are three types of tractional retinal tears: the flap tear, the tear along lattice lesions, and an operculated tear. In the classic flap (or horseshoe) tear, the retina is pulled incompletely free and forms a triangular appearance. The apex of the tear is still attached to the mobile vitreous and points towards the posterior pole. The base of the triangle parallels the vitreous base. The mobile vitreous acts to further tear the retina and separate it from the RPE. If the tear bridges a blood vessel, there can be a subsequent vitreous hemorrhage. A similar retinal tear occurs at the posterior border of lattice lesions due to the same forces, but does not have the triangular appearance of the flap tear. If an area of retinal tissue is pulled completely free by the vitreous, it is considered an operculated tear. The retinal tissue, now termed an operculum, is seen to float in the vitreous above the retinal tear.
In any case of retinal tear, if the vitreous is still attached and exerting traction on the retina through the break, the mechanical forces on the retina will be perceived by the patient as flashing lights. This indicates that there are forces active on the break which may lead to further separation of the retina from the RPE. As liquid vitreous gains access to the subretinal space, the retina is further separated from the RPE, and a rhegmatogenous retinal detachment can form.
MANAGEMENT
The standard management of tractional tears has always been prophylactic laser photocoagulation or cryoretinopexy. This creates an RPE hyperplastic scar around the break and seals the retina to the RPE, thus preventing the accumulation of subretinal fluid and subsequent rhegmatogenous retinal detachment. However, not all cases benefit from prophylactic treatment. If the patient is aphakic or pseudophakic, has a history of previous retinal detachment in either eye, is about to undergo ocular surgery, or if the tear is fresh or associated with any hemorrhage, then the patient should receive prophylactic therapy.
If the patient is symptomatic with photopsia, or if there is more than one disc diameter of subretinal fluid or elevation extending beyond the edge of the break, the patient needs treatment, as the risk of detachment is high. Any tractional tears along the edge of lattice lesions also require treatment. If there are none of the above risk factors, the patient is asymptomatic and there is no subretinal fluid, monitor the patient on a six-week, three-month, six-month, 12-month schedule. If you see progression at any follow up visit, have the patient receive prophylactic treatment.
CLINICAL PEARLS
The greater the length of time a tractional tear, or any retinal break, exists in an untreated eye without progressing to retinal detachment, the less likely the chance that it will progress.
Most tractional tears without symptoms or risk factors can be safely monitored without treatment. Often, the RPE will become hyperplastic due to the insult from the tear and form a chorioretinal scar around the break. If this happens, it becomes very unlikely that the tear will ever lead to detachment.
Retinal breaks located superiorly in the retina are no more likely to progress to retinal detachment than are breaks located inferiorly in the retina. Location of the break should not be considered when determining risk of detachment.
The patient often will report a sudden onset of either a single or multiple floating spots, along with flashing lights (photopsia). Visual symptoms will be stable within the patient's visual field. There may be precipitating ocular or head trauma. If there is a posterior vitreous detachment, there will also be one large floater. If there has been a vitreous hemorrhage, there will be multiple floaters. There may be a severe loss of vision if there is a dense vitreous hemorrhage or rhegmatogenous retinal detachment. However, in a number of cases, the patient is either asymptomatic or experienced symptoms so long ago that they were forgotten.
PATHOPHYSIOLOGY
Retinal tears result from the vitreous pulling free from the retina during vitreous detachment. During the course of the PVD, the vitreous may encounter an area where it is firmly attached to the retina. These include the optic disc, macula, along blood vessels, vitreous base, at areas of chorioretinal scarring, along the edges of lattice degeneration, and at vitreoretinal tufts. Traction at any one of these points may result in the vitreous pulling the retina free from its loose attachment to the retinal pigment epithelium with a tear developing within the sensory retina. The subsequent break in the retina can allow liquid vitreous to enter the potential subretinal space, resulting in a rhegmatogenous retinal detachment. If the vitreous remains attached to the damaged retina, traction on the edges of the break can serve to further separate the retina from the RPE.
There are three types of tractional retinal tears: the flap tear, the tear along lattice lesions, and an operculated tear. In the classic flap (or horseshoe) tear, the retina is pulled incompletely free and forms a triangular appearance. The apex of the tear is still attached to the mobile vitreous and points towards the posterior pole. The base of the triangle parallels the vitreous base. The mobile vitreous acts to further tear the retina and separate it from the RPE. If the tear bridges a blood vessel, there can be a subsequent vitreous hemorrhage. A similar retinal tear occurs at the posterior border of lattice lesions due to the same forces, but does not have the triangular appearance of the flap tear. If an area of retinal tissue is pulled completely free by the vitreous, it is considered an operculated tear. The retinal tissue, now termed an operculum, is seen to float in the vitreous above the retinal tear.
In any case of retinal tear, if the vitreous is still attached and exerting traction on the retina through the break, the mechanical forces on the retina will be perceived by the patient as flashing lights. This indicates that there are forces active on the break which may lead to further separation of the retina from the RPE. As liquid vitreous gains access to the subretinal space, the retina is further separated from the RPE, and a rhegmatogenous retinal detachment can form.
MANAGEMENT
The standard management of tractional tears has always been prophylactic laser photocoagulation or cryoretinopexy. This creates an RPE hyperplastic scar around the break and seals the retina to the RPE, thus preventing the accumulation of subretinal fluid and subsequent rhegmatogenous retinal detachment. However, not all cases benefit from prophylactic treatment. If the patient is aphakic or pseudophakic, has a history of previous retinal detachment in either eye, is about to undergo ocular surgery, or if the tear is fresh or associated with any hemorrhage, then the patient should receive prophylactic therapy.
If the patient is symptomatic with photopsia, or if there is more than one disc diameter of subretinal fluid or elevation extending beyond the edge of the break, the patient needs treatment, as the risk of detachment is high. Any tractional tears along the edge of lattice lesions also require treatment. If there are none of the above risk factors, the patient is asymptomatic and there is no subretinal fluid, monitor the patient on a six-week, three-month, six-month, 12-month schedule. If you see progression at any follow up visit, have the patient receive prophylactic treatment.
CLINICAL PEARLS
The greater the length of time a tractional tear, or any retinal break, exists in an untreated eye without progressing to retinal detachment, the less likely the chance that it will progress.
Most tractional tears without symptoms or risk factors can be safely monitored without treatment. Often, the RPE will become hyperplastic due to the insult from the tear and form a chorioretinal scar around the break. If this happens, it becomes very unlikely that the tear will ever lead to detachment.
Retinal breaks located superiorly in the retina are no more likely to progress to retinal detachment than are breaks located inferiorly in the retina. Location of the break should not be considered when determining risk of detachment.
POSTERIOR VITREOUS DETACHMENT
SIGNS AND SYMPTOMS
The patient, usually over the age of 50, will present with a sudden onset of floaters. There is usually one floating spot that is especially large and troublesome to the patient and serves as the impetus to seek immediate care. There may also be associated photopsia if the patient is experiencing vitreoretinal traction. If the patient presents with multiple floaters, there may be an associated vitreous hemorrhage, especially if there is an associated reduction in visual acuity. Patients who report diffuse floaters during routine examination usually are suffering from benign vitreous syneresis and not posterior vitreous detachment.
PATHOPHYSIOLOGY
The vitreous is comprised of collagen fibrils and glycoaminoglycans, supported by hyaluronic acid molecules. With aging, reduction in hyaluronic acid causes loss of support to the collagen. The vitreous may collapse, with detachment of the posterior hyaloid face from the optic disc. This usually is observable ophthalmoscopically as an annulus floating in the vitreous over the posterior pole. As the vitreous detaches peripherally, areas of vitreoretinal adhesion may result in a tear in the sensory retina with the ensuing possibility of a rhegmatogenous retinal detachment. If the tear bridges a blood vessel, a vitreous hemorrhage ensues.
MANAGEMENT
A PVD found asymptomatically on routine examination is benign, but requires monitoring yearly. A patient who presents with a sudden onset PVD without retinal breaks or hemorrhage requires repeat peripheral examination in six weeks, as the risk of retinal complications is highest within the six weeks following vitreous detachment. If no retinal breaks are seen at that point, routine yearly examination is all that is needed. Prophylactically treat any fresh breaks associated with a new PVD immediately with photocoagulation or cryoretinopexy.
CLINICAL PEARLS
Occasionally, a new PVD will present with a small amount of pre-retinal or vitreous hemorrhage without an observable retinal break. This patient needs a detailed peripheral exam using scleral indentation as well as Goldmann and/or Volk lens evaluation.
If no retinal breaks are initially detected, the patient needs a repeat evaluation every two weeks for six weeks to look for an occult break not originally found. If you do not observe any breaks after six weeks, the blood resulted from torn retinal or disc capillaries, and the patient is out of immediate danger.
The patient, usually over the age of 50, will present with a sudden onset of floaters. There is usually one floating spot that is especially large and troublesome to the patient and serves as the impetus to seek immediate care. There may also be associated photopsia if the patient is experiencing vitreoretinal traction. If the patient presents with multiple floaters, there may be an associated vitreous hemorrhage, especially if there is an associated reduction in visual acuity. Patients who report diffuse floaters during routine examination usually are suffering from benign vitreous syneresis and not posterior vitreous detachment.
PATHOPHYSIOLOGY
The vitreous is comprised of collagen fibrils and glycoaminoglycans, supported by hyaluronic acid molecules. With aging, reduction in hyaluronic acid causes loss of support to the collagen. The vitreous may collapse, with detachment of the posterior hyaloid face from the optic disc. This usually is observable ophthalmoscopically as an annulus floating in the vitreous over the posterior pole. As the vitreous detaches peripherally, areas of vitreoretinal adhesion may result in a tear in the sensory retina with the ensuing possibility of a rhegmatogenous retinal detachment. If the tear bridges a blood vessel, a vitreous hemorrhage ensues.
MANAGEMENT
A PVD found asymptomatically on routine examination is benign, but requires monitoring yearly. A patient who presents with a sudden onset PVD without retinal breaks or hemorrhage requires repeat peripheral examination in six weeks, as the risk of retinal complications is highest within the six weeks following vitreous detachment. If no retinal breaks are seen at that point, routine yearly examination is all that is needed. Prophylactically treat any fresh breaks associated with a new PVD immediately with photocoagulation or cryoretinopexy.
CLINICAL PEARLS
Occasionally, a new PVD will present with a small amount of pre-retinal or vitreous hemorrhage without an observable retinal break. This patient needs a detailed peripheral exam using scleral indentation as well as Goldmann and/or Volk lens evaluation.
If no retinal breaks are initially detected, the patient needs a repeat evaluation every two weeks for six weeks to look for an occult break not originally found. If you do not observe any breaks after six weeks, the blood resulted from torn retinal or disc capillaries, and the patient is out of immediate danger.
Choroidal Rupture
Signs and Symptoms
Patients who experience choroidal rupture are often younger and involved in activities, such as ball sports, which expose them to potential high-rate impact trauma to the eye or adenexa. Patients have a history, either recent or antecedent, of direct or contrecoup injury to the eye and surrounding structures.
Choroidal ruptures may be single or multiple and may affect any part of the posterior segment. In recent trauma, there may be hemorrhage in any layer ranging from the choroid to the vitreous. However, if the trauma was many years antecedent, there will be no hemorrhage unless choroidal neovascularization has developed. Visual acuity and visual field may be dramatically reduced or may be normal and the patient is asymptomatic.
Ophthalmoscopically, you will note a linear disruption that may be crescent-shaped. Often, the rupture will have the concave aspect toward the disc. There is usually significant reactive RPE hyperplasia, giving the rupture a pigmented appearance.
Pathophysiology
Direct or contrecoup injury can precipitate a choroidal rupture. Hemorrhage and edema may be present initially, but will resolve. Typically, reactive hyperplasia gives the rupture a heavily pigmented appearance. Often, the overlying retina is undisturbed in choroidal rupture. However, if the RPE is disturbed and becomes hyperplastic and invades the sensory retina, visual dysfunction ensues.
Due to the subsequent disruption of Bruch’s membrane that occurs in choroidal rupture, choroidal neovascular membranes may develop within the rupture. This may be a late development that can occur up to five years after the precipitating trauma.
Management
There is no direct intervention in the acute phase of choroidal rupture. Educate patients about their condition and prescribe protective eye wear. Monitor the patient funduscopically for at least five years for the development of choroidal neovascularization within the rupture scar. Any late bleeding should receive a fluorescein angiogram to determine if a choroidal neovascular membrane has developed. Choroidal neovascular membranes resulting from choroidal rupture have a tendency to spontaneously involute. For this reason, laser photocoagulation is indicated only if there is imminent threat to vision.
Clinical Pearls
Choroidal neovascularization can occur five years after the initial trauma.
Sub-retinal hemorrhage from choroidal neovascularization is the most common cause of late vision loss.
As the retina overlying a choroidal rupture may be unaffected, patients may retain excellent visual function and present asymptomatically years after the trauma. A patient may have a rupture between the disc and macula, yet retain normal acuity.
Patients who experience choroidal rupture are often younger and involved in activities, such as ball sports, which expose them to potential high-rate impact trauma to the eye or adenexa. Patients have a history, either recent or antecedent, of direct or contrecoup injury to the eye and surrounding structures.
Choroidal ruptures may be single or multiple and may affect any part of the posterior segment. In recent trauma, there may be hemorrhage in any layer ranging from the choroid to the vitreous. However, if the trauma was many years antecedent, there will be no hemorrhage unless choroidal neovascularization has developed. Visual acuity and visual field may be dramatically reduced or may be normal and the patient is asymptomatic.
Ophthalmoscopically, you will note a linear disruption that may be crescent-shaped. Often, the rupture will have the concave aspect toward the disc. There is usually significant reactive RPE hyperplasia, giving the rupture a pigmented appearance.
Pathophysiology
Direct or contrecoup injury can precipitate a choroidal rupture. Hemorrhage and edema may be present initially, but will resolve. Typically, reactive hyperplasia gives the rupture a heavily pigmented appearance. Often, the overlying retina is undisturbed in choroidal rupture. However, if the RPE is disturbed and becomes hyperplastic and invades the sensory retina, visual dysfunction ensues.
Due to the subsequent disruption of Bruch’s membrane that occurs in choroidal rupture, choroidal neovascular membranes may develop within the rupture. This may be a late development that can occur up to five years after the precipitating trauma.
Management
There is no direct intervention in the acute phase of choroidal rupture. Educate patients about their condition and prescribe protective eye wear. Monitor the patient funduscopically for at least five years for the development of choroidal neovascularization within the rupture scar. Any late bleeding should receive a fluorescein angiogram to determine if a choroidal neovascular membrane has developed. Choroidal neovascular membranes resulting from choroidal rupture have a tendency to spontaneously involute. For this reason, laser photocoagulation is indicated only if there is imminent threat to vision.
Clinical Pearls
Choroidal neovascularization can occur five years after the initial trauma.
Sub-retinal hemorrhage from choroidal neovascularization is the most common cause of late vision loss.
As the retina overlying a choroidal rupture may be unaffected, patients may retain excellent visual function and present asymptomatically years after the trauma. A patient may have a rupture between the disc and macula, yet retain normal acuity.
Pars Planitis
Signs and Symptoms
The patient with par planitis is typically a younger patient with no significant medical history. Patients are frequently asymptomatic, but may present with modestly diminished vision that is slowly progressive, as well as complaints of floaters. A history of similar occurrences of symptoms may be disclosed.
The first observable sign of pars planitis is the presence of vitreal cells in an active vitritis. The vitritis may cause vitreous degeneration with a resultant posterior vitreous detachment. The vitritis frequently will result in an accumulation of inflammatory exudate. The accumulation may be small (snowballs) or extensive (snowbanks) and may occur anywhere in the fundus but is typically regulated to the inferior fundus by gravity. There also may be the presence of cataracts, especially posterior subcapsular, and cystoid macular edema. In extreme cases, there may be retinal neovascularization.
Pathophysiology
Pars planitis is a true posterior/intermediate uveitis that chronically affects younger, healthy patients. Pars planitis is idiopathic and unassociated with systemic disease. However, there have been some implications of an association of autoimmune disease (juvenile rheumatoid arthritis) and demyelinating disease. There are exacerbations and remissions and typically this disorder runs a very long course. Inflammatory mediators will increase vasopermeability of retinal capillaries resulting in posterior segment inflammatory cells as well as cystoid macular edema (CME). Vision loss occurs due to cataracts and CME.
Management
Pars planitis is generally benign. Vision loss tends to be mild, if it occurs at all. Only in extreme cases is vision loss profound. In these cases, the cause of vision loss is retinal neovascularization with its attendant complications of vitreous hemorrhage and tractional retinal detachment. As pars planitis is typically a relatively benign disease, treatment should be conservative and often involves only periodic monitoring.
If treatment is undertaken due to mild vision loss from cystoid macular edema or vitreous clouding, then steroids form the cornerstone. Topical steroids are employed only if there is a concomitant anterior uveitis. However, in these cases, the anterior chamber reaction is not a true anterior uveitis, but a spill-over from the posterior uveitis. Thus, topical steroids are rarely indicated. Oral prednisone is more commonly used. However, once a commitment to use oral steroids is made, typically they must be used for months. With this treatment comes the possible attendant complications of steroid induced cataracts and glaucoma. In severe cases, sub-tenon’s injections of steroids may be used, as well as vitrectomy to clear the vitreous and cyclocryotherapy to destroy the inflamed areas and infiltrates. Topical and oral non-steroidal anti-inflammatory agents have been used to treat attendant CME with some success.
In most cases, pars planitis is unassociated with systemic disease. However, in order to avoid a possible mis-diagnosis, have the patient tested for both syphilis and sarcoidosis as these diseases may present a similar clinical picture.
Clinical Pearls
Posterior vitreous detachment is rare in younger patients; however, PVD is quite common in pars planitis. Consider pars planitis when encountering PVD in younger patients.
Always consider pars planitis in cases of asymptomatic vitreous cells in healthy, younger patients.
When suspecting pars planitis, carefully examine the inferior retina and vitreous for snowballs and snowbanking.
Pars planitis can be safely monitored without treatment. If the decision to treat is made, however, expect to treat with oral steroids for several months.
If pars planitis is definitively diagnosed, medical testing is unnecessary. However, if the diagnosis is in question, remember that the differential includes sarcoidosis, syphilis, multiple sclerosis with vascular sheathing and intermediate uveitis, toxoplasmosis, and toxocariasis.
The patient with par planitis is typically a younger patient with no significant medical history. Patients are frequently asymptomatic, but may present with modestly diminished vision that is slowly progressive, as well as complaints of floaters. A history of similar occurrences of symptoms may be disclosed.
The first observable sign of pars planitis is the presence of vitreal cells in an active vitritis. The vitritis may cause vitreous degeneration with a resultant posterior vitreous detachment. The vitritis frequently will result in an accumulation of inflammatory exudate. The accumulation may be small (snowballs) or extensive (snowbanks) and may occur anywhere in the fundus but is typically regulated to the inferior fundus by gravity. There also may be the presence of cataracts, especially posterior subcapsular, and cystoid macular edema. In extreme cases, there may be retinal neovascularization.
Pathophysiology
Pars planitis is a true posterior/intermediate uveitis that chronically affects younger, healthy patients. Pars planitis is idiopathic and unassociated with systemic disease. However, there have been some implications of an association of autoimmune disease (juvenile rheumatoid arthritis) and demyelinating disease. There are exacerbations and remissions and typically this disorder runs a very long course. Inflammatory mediators will increase vasopermeability of retinal capillaries resulting in posterior segment inflammatory cells as well as cystoid macular edema (CME). Vision loss occurs due to cataracts and CME.
Management
Pars planitis is generally benign. Vision loss tends to be mild, if it occurs at all. Only in extreme cases is vision loss profound. In these cases, the cause of vision loss is retinal neovascularization with its attendant complications of vitreous hemorrhage and tractional retinal detachment. As pars planitis is typically a relatively benign disease, treatment should be conservative and often involves only periodic monitoring.
If treatment is undertaken due to mild vision loss from cystoid macular edema or vitreous clouding, then steroids form the cornerstone. Topical steroids are employed only if there is a concomitant anterior uveitis. However, in these cases, the anterior chamber reaction is not a true anterior uveitis, but a spill-over from the posterior uveitis. Thus, topical steroids are rarely indicated. Oral prednisone is more commonly used. However, once a commitment to use oral steroids is made, typically they must be used for months. With this treatment comes the possible attendant complications of steroid induced cataracts and glaucoma. In severe cases, sub-tenon’s injections of steroids may be used, as well as vitrectomy to clear the vitreous and cyclocryotherapy to destroy the inflamed areas and infiltrates. Topical and oral non-steroidal anti-inflammatory agents have been used to treat attendant CME with some success.
In most cases, pars planitis is unassociated with systemic disease. However, in order to avoid a possible mis-diagnosis, have the patient tested for both syphilis and sarcoidosis as these diseases may present a similar clinical picture.
Clinical Pearls
Posterior vitreous detachment is rare in younger patients; however, PVD is quite common in pars planitis. Consider pars planitis when encountering PVD in younger patients.
Always consider pars planitis in cases of asymptomatic vitreous cells in healthy, younger patients.
When suspecting pars planitis, carefully examine the inferior retina and vitreous for snowballs and snowbanking.
Pars planitis can be safely monitored without treatment. If the decision to treat is made, however, expect to treat with oral steroids for several months.
If pars planitis is definitively diagnosed, medical testing is unnecessary. However, if the diagnosis is in question, remember that the differential includes sarcoidosis, syphilis, multiple sclerosis with vascular sheathing and intermediate uveitis, toxoplasmosis, and toxocariasis.
Subscribe to:
Posts (Atom)