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Saturday, December 25, 2010

KERATITIS SICCA / DRY EYE SYNDROME

SIGNS AND SYMPTOMS
As the name implies, patients with keratitis sicca or dry eye syndrome typically present with complaints of dry, burning eyes and a "sandy" or "gritty" foreign body sensation. Occasionally, patients will report excess tearing (epiphora). Often, the symptoms are exacerbated by poor air quality and low humidity, and are more prominent later in the day. Upon inspection, most patients demonstrate a relatively white and quiet eye. Key slit lamp findings include a negligible tear meniscus at the lower lid and a reduced tear break-up time (TBUT), generally less than ten seconds.

Fluorescein staining will usually reveal punctate epithelial keratopathy in the interpalpebral region. In severe cases, the cornea and/or conjunctiva may also stain with rose bengal. Filaments-tags of mucus, epithelial cells and tear debris-may also stain with fluorescein and rose bengal; filamentary keratitis is an extreme sequela of keratitis sicca.

PATHOPHYSIOLOGY
Dry eye syndrome results primarily from compromise to either the quantity or quality of the precorneal tear film. Tears are composed of a mucin layer, a water or aqueous layer, and an oil layer. Deficiencies in any one of these components may create a tear film which is incapable of properly moistening the eye, resulting in desiccation and symptomatic complaints. In addition, irregularities in the blink mechanism or conditions affecting the regularity of the ocular surface (e.g., pterygia, keratoconus) may further interfere with proper wetting of the cornea. Many drugs can also temporarily decrease lacrimal gland secretions, such as antihistamines, phenothiazine anti-anxiety medications, oral contraceptives and atropine derivatives. Collagen vascular disorders such as rheumatoid arthritis and Sjögren's syndrome also have a high association with dry eye syndrome.

MANAGEMENT
Management is aimed at replenishing the eyes' moisture and/or delaying evaporation of the patient's natural tears. Begin by recommending that the patient instill an ophthalmic lubricant every hour or more as needed, then taper the therapy based upon patient response and compliance. A lubricating ointment used at bedtime may provide additional comfort. For those patients who derive little relief from this therapy, or who fail to comply, punctal occlusion may offer a more realistic and less complicated management strategy. First, test the patient's response using dissolvable collagen plugs to ensure the therapy will provide relief from symptoms without epiphora. If successful, occlude the inferior puncta using silicone plugs. In severe cases consider occluding both the inferior and superior puncta, or recommend surgical cautery.

CLINICAL PEARLS

Often, patients with dry eye syndrome are more symptomatic than their clinical signs would imply. Typically, the diagnosis is based more on subjective complaints than slit lamp findings.

Educate patients early and often that dry eye syndrome cannot be cured outright. Rather, the therapy aims to control symptoms and reduce discomfort.

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