Trachoma - Causes, Symptoms and Treatments

The most common cause of preventable blindness in underdeveloped areas of the world, trachoma is a chronic form of keratoconjunctivitis. This infection is usually confined to the eye but may have a systemic component. Although trachoma itself is self-limiting, it causes permanent damage to the cornea and conjunctiva by scarring the lids; severe trachoma may lead to blindness, especially if a secondary bacterial infection develops. Early diagnosis and treatment (before trachoma results in scar formation) ensure recovery but without immunity to reinfection. Trachoma is prevalent in Africa, Latin America, and Asia, particularly in children; in the United States, it is prevalent among the Native Americans of the Southwest.

Causes of Trachoma:

Trachoma results from infection by Chlamydia trachomatis, a gram-negative, obligate intracellular bacteria. These microbes are transmitted from eye to eye by flies and gnats and by hand-eye contact in endemic areas.

Trachoma is spread by close contact between family members or among schoolchildren. Other predisposing factors include poverty and poor hygiene due to lack of water. Patients in hot, dusty climates are at greater risk.

Signs and symptoms of Trachoma:

Trachoma begins with a mild infection resembling bacterial conjunctivitis (visible conjunctival follicles, red and edematous eyelids, pain, photophobia, tearing, and exudation).

After about 1 month, if the infection is untreated, conjunctival follicles enlarge into inflamed papillae that later become yellow or gray. At this stage, small blood vessels invade the cornea under the upper lid.

Eventually, severe scarring and contraction of the eyelids cause entropion; the eyelids turn inward and the lashes rub against the cornea, producing corneal scarring and visual distortion. In the later stages, severe conjunctival scarring may obstruct the lacrimal ducts and cause dry eyes.

Diagnosis of Trachoma:

Follicular conjunctivitis with corneal infiltration and upper lid or conjunctival scarring suggest trachoma, especially in endemic areas, when these symptoms persist longer than 3 weeks.

Microscopic examination of a Giemsastained conjunctival scraping confirms the diagnosis by showing cytoplasmic inclusion bodies, some polymorphonuclear reaction, plasma cells, Leber's cells (large macrophages containing phagocytosed debris), and follicle cells.

Treatment of Trachoma:

Primary treatment of trachoma consists of 3 to 4 weeks of topical or systemic antibiotic therapy with tetracycline, erythromycin, or sulfonamides. (Tetracycline is contraindicated in pregnant females because it may adversely affect the fetus, and in children under age 7, in whom it may discolor teeth permanently.) Severe entropion requires surgical correction.

Special considerations and Prevention tips:

1. Because no definitive preventive measure exists (vaccines offer temporary and partial protection, at best), stress the need for strict compliance with the prescribed drug therapy.

2. If ordered, teach the patient or family members how to instill eyedrops correctly.

3. Emphasize the importance of hand washing and making the best use of available water supplies to maintain good personal hygiene.

4. To prevent trachoma, warn patients not to allow llies or gnats to settle around the eyes.