Q: A 30-year-old white female came in with follicular conjunctivitis that won’t respond to topical treatment. I’m thinking it could be chlamydia—but how can I be sure?

A: “First, rule out other causes of chronic conjunctivitis,” says Tammy Than, OD, associate professor at University of Alabama at Birmingham School of Optometry. “For instance, molluscum contagiosum also causes follicular conjunctivitis. So, look carefully for hidden lesions between the eyelashes.”

If none are present, you’re probably right to be suspicious of chlamydial conjunctivitis. Indeed, chlamydia is the most frequently reported sexually transmitted bacterial infection in the United States, and the most common cause of chronic follicular conjunctivitis.¹ But if it’s not in your differential, you’ll never diagnose it.

Most frequent in young, sexually active adults, chlamydial (adult inclusion) conjunctivitis can be transmitted sexually or by hand-to-eye contact, Dr. Than says. It generally presents as a chronic, unilateral red eye with large follicles in the inferior conjunctival fornix. An enlarged preauricular lymph node is also common. A case history, with direct and open questioning about past sexually transmitted diseases (STDs), is probably the most important component of the exam. You must ask your patient about possible STDs, because she will not volunteer the information.

Follicular conjunctivitis due to chlamydia. Photo: Ron Melton, OD, and Randall Thomas, OD.

Definitive diagnosis requires a lab test. This includes Giemsa staining, cell culture, serum immunoglobulin G (IgG) titers to Chlamydia species, enzyme-linked immunosorbent assay and polymerase chain reaction (PCR).

“Select a test with high specificity and sensitivity,” Dr. Than says. “The Charles T. Campbell Ophthalmic Microbiology Lab at the Eye and Ear Institute in Pittsburgh recommends Giemsa stain or PCR tests for chlamydia.” (For further information and collection instructions, see the lab’s site at http://eyemicrobiology.upmc.com/chlamydia.htm.)

Treatment is straightforward and simple.

“Due to the chronic nature of chlamydial conjunctivitis, many patients present with a history of using several different topical antibiotics without resolution of the condition,” Dr. Than says. “So, suspected or confirmed chlamydia cases require systemic treatment.”

The treatment of choice is a single, 1g dose of azithromycin. Other therapies, which each require a minimum of seven days of treatment, include tetracycline 500mg four times a day, doxycycline 100mg twice a day, or erythromycin 500mg four times a day. Avoid tetracyclines in children and in women who are pregnant or breastfeeding.

Note that Vigamox and Moxeza (moxifloxacin 0.5%, Alcon) are both indicated for conjunctivitis caused by Chlamydia trachomatis. Erythromycin ointment is another topical therapy. But because chlamydia is a systemic disease, systemic treatment is usually preferred.

Patients should return for monitoring in two to three weeks.

“Because chlamydia often occurs concomitantly with other sexually-transmitted diseases, the patient also needs to be referred to a medical specialist,” Dr. Than says. 

Often, patients have no genitourinary symptoms. Therefore, chlamydia is likely significantly underreported. For the same reason, it can lead to devastating long-term consequences, such as pelvic inflammatory disease (PID) and infertility.

Furthermore, all sex partners from the past two months need to be informed, seen by a health care provider and treated, according to the Centers for Disease Control and Prevention. Simultaneous treatment of current partner(s) needs to occur to prevent re-infection.

Lastly, you must report all cases of chlamydia and gonorrhea to your state health department.

1. Rubenstein JB, Virasch V. Conjunctivitis: Infectious and Noninfectious. In: Yanoff M, Duker JS, eds. Ophthalmology. 3rd ed. St. Louis: Mosby Elsevier; 2008: 231.