Ocular chlamydia, formally known as inclusion conjunctivitis, is an infection of the eye’s outer membrane caused by the bacterium Chlamydia trachomatis. This organism is the same one responsible for the most common sexually transmitted bacterial infection worldwide. The ocular form of the disease is highly contagious and spreads readily through specific contact pathways.
Mechanisms of Ocular Transmission
The spread of Chlamydia trachomatis to the eyes occurs through direct contact with infected genital secretions. In sexually active adults, the most frequent way the infection begins is through self-inoculation, or autoinoculation. This involves transferring the bacterium from an infected urogenital or rectal site to the eye via contaminated hands. Since genital infections are often asymptomatic, an individual may unknowingly introduce the organism to the conjunctiva.
The bacteria can also be transmitted through indirect contact with contaminated objects, known as fomites. Sharing personal items like towels, washcloths, pillowcases, or eye makeup can facilitate the spread. The infection has also been documented to spread through exposure to poorly chlorinated water, such as in swimming pools or hot tubs.
A significant transmission route occurs during childbirth, resulting in neonatal conjunctivitis. If a pregnant individual has an untreated chlamydial infection, the newborn can acquire the bacteria while passing through the birth canal. Approximately 30% to 50% of newborns exposed during delivery will develop this eye infection, which typically manifests one to two weeks after birth. Screening and treatment for chlamydia during pregnancy is important.
Identifying Symptoms of Eye Infection
The clinical presentation of chlamydial conjunctivitis is often subtle and chronic, making it easy to confuse with common forms of “pink eye.” Symptoms typically appear between 2 and 19 days after initial exposure. The infection frequently affects only one eye initially, though it can eventually spread to both.
A common sign is persistent redness of the eye (hyperemia), accompanied by a watery or mucopurulent discharge that can cause the eyelids to stick together, especially upon waking. Patients often report a foreign body sensation, or grittiness, and may experience eyelid swelling. Chlamydial infection is characterized by a marked follicular response—small bumps that form on the underside of the upper and lower eyelids (tarsal conjunctiva).
Another diagnostic indication is an enlarged lymph node in front of the ear (preauricular lymphadenopathy). The chronicity of the symptoms, often lasting for many weeks or months, is a distinguishing feature. Because symptoms are similar to other eye infections, this conjunctivitis is frequently misdiagnosed and fails to improve after standard topical antibiotic eye drops.
Treatment and Stopping the Spread
Accurate diagnosis requires laboratory confirmation, typically involving a nucleic acid amplification test (NAAT) performed on a conjunctival swab sample. This testing distinguishes it from other types of conjunctivitis with similar symptoms. Once confirmed, treatment must address both the eye infection and the underlying systemic infection, which is present in a majority of adult cases.
Treatment mandates the use of systemic antibiotics taken by mouth, because the bacteria often reside in the genital tract as well. Common oral treatments for adults include a single dose of azithromycin or a course of doxycycline taken for one to two weeks. Topical antibiotic eye drops or ointments may be used to manage eye symptoms, but they cannot cure the infection alone. For pregnant individuals, alternatives such as erythromycin are used, as certain antibiotics like doxycycline are contraindicated.
To prevent the cycle of infection and reinfection, the patient’s sexual partners must also be tested and treated with oral antibiotics, even if they show no symptoms. Strict hygiene measures are necessary to stop person-to-person spread and autoinoculation. Frequent handwashing is recommended, especially after touching the genital area, and touching the eyes should be avoided. Personal items, including towels, washcloths, and cosmetics, should not be shared while the infection is active.