Trachoma is the leading infectious cause of blindness worldwide.
The bacterium that causes trachoma spreads through direct contact with the eye, nose or throat secretions of infected people. It’s very contagious and almost always affects both eyes. Untreated trachoma can lead to blindness.
Trachoma is preventable and, if treated early, the prognosis for people with trachoma is excellent.
The cause of trachoma is certain subtypes of Chlamydia trachomatis, a bacterium that can also cause the sexually transmitted disease chlamydia.
Trachoma spreads through contact with discharge from the eyes or nose of an infected person. Hands, clothing, towels and insects can all be routes for transmission. In the world’s developing countries, flies are a major means of transmission.
The principal signs and symptoms in the early stages of trachoma include:
- Mild itching and irritation of the eye
- Discharge from the eye containing mucus or pus
As the disease progresses, later trachoma symptoms include:
- Marked light sensitivity (photophobia)
- Blurred vision
- Eye pain
Young children are particularly susceptible to infection, but the disease progresses slowly, and the more painful symptoms may not emerge until adulthood.
The World Health Organization has identified a grading system with five stages in the development of trachoma. The stages are:
- Inflammation — follicular. The infection is just beginning. Five or more follicles — small bumps that contain lymphocytes, a type of white blood cell — are visible with magnification on the inner surface of the upper eyelid (conjunctiva).
- Inflammation — intense. In this stage, the eye is now highly infectious and becomes irritated, with a thickening or swelling of the upper eyelid.
- Eyelid scarring. Repeated infections lead to scarring of the inner eyelid; the scars often appear as white lines when examined with magnification. The eyelid may become distorted and may turn in (entropion).
- Trichiasis, or ingrown eyelashes. The scarred inner lining of the eyelid continues to deform, causing the lashes to turn in so that they rub on and scratch the transparent outer surface of the eye (cornea). Only about 1 percent of people with trachoma develop this painful condition.
- Corneal clouding. The cornea becomes affected by an inflammation that is most commonly seen under the upper lid. Continual inflammation compounded by scratching from the in-turned lashes leads to clouding of the cornea. Secondary infection can lead to development of ulcers on the cornea and eventually partial or complete blindness.
All the signs of trachoma are more severe in the upper lid than in the lower lid. With advanced scarring, the upper lid may show an S-shaped curve. In addition, the lubricating glandular tissue in the lids — including the tear-producing glands (lacrimal glands) — can be affected. This can lead to extreme dryness, aggravating the problem even more.
When to see a doctor
Call your doctor if you or your child has itching, irritation or discharge from the eyes, especially if you recently traveled to an area where trachoma is common.
One episode of infection with Chlamydia trachomatis is easily treated with early detection and use of antibiotics. However, repeated infection can lead to complications, including:
- Scarring of the inner eyelid
- Eyelid deformities
- Inward folding of the eyelid (entropion)
- Ingrown eyelashes
- Corneal scarring or cloudiness
- Partial or complete vision loss
Most people with trachoma in its initial stages display no signs or symptoms. In areas where the disease is endemic, a doctor can diagnose trachoma through a clinical examination or through sending a sample of bacteria from your eyes to be cultured and tested in a laboratory.
Trachoma treatment options depend on the stage of development.
In the early stages of trachoma, treatment with antibiotics alone may be enough to eliminate the infection. The two drugs currently in use include a tetracycline eye ointment and oral azithromycin (Zithromax). Although azithromycin appears to be more effective than tetracycline, azithromycin is more expensive. In poor communities, the drug used often depends on which one is available and affordable.
Treatment of later stages of trachoma — including painful eyelid deformities — may require surgery. In eyelid rotation surgery (bilamellar tarsal rotation), a doctor makes an incision in the scarred lid and rotates the eyelashes away from the cornea. The procedure limits the progression of corneal scarring and can improve eyesight. Generally, this procedure can be performed on an outpatient basis. The procedure takes less than 15 minutes and has a good long-term success rate.
If the cornea has become clouded enough to seriously impair vision, corneal transplantation is an option that offers some hope of improved vision; frequently, however, the results are not good.