Thursday, December 23, 2010

Conjunctivitis with Pseudomembrane

Signs and Symptoms
Often, conjunctivitis is discovered by most patients in the morning, when they notice, upon waking, that their eyelids are "stuck together." The classic signs and symptoms of conjunctivitis include ocular redness secondary to palpebral and or bulbar conjunctival injection, irritation, itching, lacrimation, discharge, and possibly keratitis with decreased vision. Conjunctival follicular and papillary response, discharge, subepithelial infiltration, subconjunctival hemorrhage, corneal epitheliopathy, symblepharon formation and lymphadenopathy are variables dictated by the etiology.

A true membrane forms when the fibrinous excretory or inflammatory exudate that is secreted by invading microorganisms or ocular tissues permeates the superficial layers of the conjunctival epithelium. True membranes become interdigitated with the vascularity of the conjunctival epithelium. They are firmly adherent, and tearing and bleeding often result when removed. B-hemolytic streptococci, Neisseria gonorrhoeae, Corynebacterium diphtheriae, Stevens-Johnson syndrome (severe systemic vesiculobullous eruptions affecting the mucous membranes-erythema multiforme) and chemical or thermal burns are among the common etiologic sources.

Pseudomembranes consist of coagulated exudate that is loosely adherent to the inflamed conjunctiva. They are typically not integrated with the conjunctival epithelium and can be removed by peeling, leaving the conjunctival epithelium intact. Their removal produces little if any bleeding. Epidemic keratoconjunctivitis (EKC), ligneous conjunctivitis (a rare idiopathic bilateral membranous/pseudomembranous conjunctivitis seen in children with thick, ropy, white discharge on the upper tarsal conjunctiva), allergic conjunctivitis, and bacterial infections are the primary causes.

Epidemic keratoconjunctivitis (EKC) often presents as a bilateral, inferior palpebral, follicular conjunctivitis, with epithelial and subepithelial keratitis and normal corneal sensation. It is extremely contagious. The subepithelial infiltrates (SEI) are typically concentrated in the central cornea. Mild EKC is regularly caused by adenovirus virus serotypes 1, 2, 3, 4. The more severe form of the disease is caused by virus serotypes 5, 8, 19 and 37.

Pharyngoconjunctival fever (PCF) is characterized by history of fever, sore throat, upper respiratory infection, and follicular conjunctivitis. It may be unilateral or bilateral. It is caused regularly by adenovirus 3 and 7. The cornea is rarely affected and infiltrates are uncommon. While the virus is shed from the conjunctiva in 14 days, it remains in fecal excretion for 30 days. This may explain why some epidemics center around swimming pools in summer. The disorder varies in severity and may persist for four days to two weeks.

In most cases, because viral conjunctivitis is contagious and self-limiting, the primary function of management is to increase patient awareness and comfort by providing education and decreasing symptomatology. Patients should be kept home from work or school until contagious discharge is eliminated. Patients should be warned not to use common utensils or linens.

If pseudo- or true membranes are present, debride them using a wet cotton-tipped applicator or forceps. Include supportive therapies such as cold compress and topical tear solutions, topical vasoconstrictors (Naphcon A), topical NSAID preparations (Acular, Voltaren), and topical steroids (Flarex, Pred Forte, Vexol) b.i.d. to q.i.d. Topical antibiotic/steroid combination therapy (Tobradex, Maxitrol) QID is indicated if the infection has a suspected bacterial source. Cycloplegia is only necessary in the most severe cases. When you suspect bacterial etiology, conjunctival scrapings may provide differential diagnostic information.

A new drug is on the horizon for treating entities causing pseudomembraneous conjunctivitis. Cidofovir, a topically applied DNA analog, has been proven clinically efficacious in the treatment of adenoviral conjunctivitis and epidemic keratoconjunctivitis and is currently awaiting approval for commercial use.

Clinical Pearls

The four clinical features that must be considered in the differential diagnosis of any conjunctival inflammation include:r

- Type of discharge (watery, mucoid, purulent, mucopurulent)
- Type of conjunctival reaction (follicular or papillary)
- Presence or absence of membrane or pseudomembrane formation
- Presence or absence of lymphadenopathy (association with sexually transmitted or viral origin)

Epidemic viral conjunctivitis, epidemic keratoconjunctivitis (EKC) and pharyngoconjunctival fever (PCF) can be caused by a number of different viruses and are probably the most common causes of pseudomembranous conjunctivitis.

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