Research suggests at least two different ways in which the antibiotic Zithromax may lead to eye injuries that in the most extreme cases can lead to permanent blindness.

One study suggests Zithromax may be linked to an increased risk of reinfection for patients with trachoma, a condition known to cause blindness.

Trachoma is a type of eye infection caused by the Chlamydia trachomatis bacterium. It affects the conjunctiva, the membrane that lines the eyelid and connects it to the white of the eye. This infection can cause the conjunctiva to become inflamed and irritated.

In more advanced stages of trachoma, vision may be obstructed by blood vessels that grow across the cornea. Trachoma can also cause scarring of the eye tissue.

By one measure, 15 percent of cases of blindness are caused by trachoma, making it the leading preventable cause of blindness in the world.

Since trachoma is caused by bacteria, antibiotics like Zithromax are part of a standard treatment regimen. But a study published in the September 2006 issue of the Journal of the American Medical Association suggests that treating trachoma with Zithromax may come with an increased risk of trachoma reinfection.

The study looked at results of using the World Health Organization’s antibiotic-based SAFE strategy in certain communes in Vietnam from 2000 to 2003.

The communes in the study used Zithromax, referred to in the study by its generic name azithromycin. Researchers compared these data with results from another commune that used a surgery-only treatment strategy.

The researchers found that reinfection rates increased significantly in the communes that used Zithromax. They concluded that compared to the commune that used only surgery, the risk of reinfection was about four times higher for communes using Zithromax.

What caused the higher risk in the Zithromax groups isn’t known for sure. The study’s authors hypothesize that Zithromax may interfere with the patient’s immune response during the infection in a way that promotes trachoma reinfection.

Other Ways Zithromax Leads to Eye Problems

Another way in which Zithromax use can be linked to blindness is through a condition known as Stevens-Johnson syndrome, or SJS. This condition is most often the result of a reaction to a medication. Zithromax is one of many drugs have been linked to the development of SJS.

The trademark symptoms of SJS are painful areas of rash on the skin that blister and ultimately peel away. The loss of the outer layer of skin exposes the patient to infection, and infections that result from SJS are the most frequent cause of death for SJS victims.

SJS is also known for causing eye problems. The condition can also attack the mucous membranes, the soft tissue that lines much of the inside of the digestive system, respiratory system, and the eyes. SJS eye problems typically lead to conjunctivitis, an inflammation of the conjunctiva.

This condition can make the eyes become painful, irritated and swollen. They can become so purulent that they seal shut.

Other typical SJS eye injuries include scarring of the conjunctiva and blisters or perforation of the cornea. In more extreme cases, eye problems like these can result in permanent vision loss.