Trachoma, a major cause of preventable blindness worldwide, is an infectious eye disease caused by the bacterium Chlamydia trachomatis. The infection spreads easily through contact with eye or nasal discharge from an infected person, often via hands, clothing, or eye-seeking flies. Trachoma can be cured, particularly if the infection is caught and treated early before it causes permanent damage. Curability depends on the stage of progression, with antibiotics eliminating the infection and surgery addressing advanced complications.
The Stages of Trachoma Progression
Trachoma is a slowly progressing disease that begins in childhood, with the most severe, blinding consequences often appearing in adulthood. The World Health Organization (WHO) uses a simplified grading system to classify the disease into five distinct stages that determine the appropriate intervention. The initial stage, Trachomatous inflammation—follicular (TF), involves the appearance of small, raised bumps containing white blood cells on the inner surface of the upper eyelid.
The infection progresses to Trachomatous inflammation—intense (TI), where the eyelid becomes visibly swollen, thickened, and more severely inflamed. Repeated infections trigger a chronic immune response that leads to the third stage, Trachomatous scarring (TS), where white, fibrous bands begin to form on the inside of the eyelid. These first three stages represent the active or scarring phases of the disease.
Medical Treatment for Active Infection
The primary method for eliminating the active Chlamydia trachomatis infection is through the use of antibiotics. This intervention is the “A” component of the WHO’s comprehensive SAFE strategy (Surgery, Antibiotics, Facial cleanliness, Environmental improvement). The antibiotic of choice is a single oral dose of Azithromycin, which is highly effective and simple to administer, a key feature for large-scale public health programs.
In areas where the disease is widespread, mass drug administration (MDA) is implemented, treating entire communities or specific high-risk groups, such as children. This community-wide treatment is crucial for reducing the overall reservoir of the bacterium and interrupting the cycle of transmission. Topical tetracycline eye ointment is sometimes used as an alternative for individuals who cannot take Azithromycin.
If the active infection is successfully treated in the early inflammatory stages (TF or TI), the disease is cured, and the progression to blinding complications is prevented. For communities with very high rates of infection, annual mass treatment may be necessary for several years until the prevalence of active trachoma in young children drops below a certain threshold.
Surgical Correction for Advanced Disease
When the infection has progressed past the inflammatory stages, scarring of the eyelid can cause Trachomatous trichiasis (TT). In this fourth stage, the scar tissue contracts, causing the eyelid margin to turn inward (entropion). This directs the eyelashes to rub painfully against the cornea. This constant abrasion damages the eye’s surface, leading to ulcers, clouding, and eventually, the fifth stage: permanent corneal opacity (CO) and blindness.
Surgical intervention is the only way to correct the structural damage of trichiasis and prevent blindness. The most common procedure is a lid rotation surgery, which rotates the eyelid margin outward. This redirects the eyelashes away from the eyeball, immediately relieving the scraping and protecting the cornea from further harm.
While surgery cannot restore vision lost due to long-standing corneal opacity, it is highly successful at preserving remaining sight and preventing total blindness. The surgery for trichiasis, the “S” component of the SAFE strategy, is often performed by trained ophthalmic nurses or assistants in remote settings.
Preventing Transmission and Recurrence
Sustained elimination of trachoma requires breaking the transmission cycle to prevent reinfection after medical and surgical treatments have been administered. This is achieved through the remaining two components of the WHO’s SAFE strategy: Facial cleanliness (F) and Environmental improvement (E). Promoting facial cleanliness, particularly in young children who are the primary reservoir of the infection, helps reduce the spread of the bacterium.
Washing the face with soap and water removes the ocular and nasal secretions that contain the bacteria. Environmental improvements aim to reduce the risk of infection and re-infection across the community. This includes providing better access to clean water sources and improving sanitation through the provision of latrines. These measures also help control eye-seeking flies, which transmit the bacteria from person to person.