One might not expect to get uveitis from antibiotics, but a recent study shows that condition occurs more frequently with use of certain fluoroquinolone antibiotics.

In an article published in JAMA Ophthalmology, researchers reported on what they believed was the first epidemiological study of the relationship between uveitis and moxifloxacin, an antibiotic marketed as Avelox. They studied data from a cohort of adult men from January 2001 to December 2011. For those men who developed uveitis, the researchers compared whether they used various fluoroquinolone antibiotics – moxifloxacin, levofloxacin (the generic equivalent of Levaquin), or ciprofloxacin hydrochloride (the generic equivalent of Cipro) – or no antibiotics at all.

The researchers found the highest risk of uveitis among current first-time users of moxifloxacin, who were almost three times as likely to develop uveitis during treatment. Current first-time users of ciprofloxacin also showed an increased risk of uveitis, though not as much as users of moxifloxacin. The researchers found no statistically significant increase in uveitis among levofloxacin users.

Uveitis from Antibiotics

Uveitis is an inflammation of parts of the eye known as the uveal tract. This tract consists of the iris, the ciliary body, and the choroid. It typically manifests with some combination of pain, redness, floaters and loss of vision. Other symptoms are possible, and they may vary depending on the part of the uveal tract that is inflamed. The patient may experience pain with exposure to bright light. With posterior uveitis, inflammation of the optic nerve is a possibility, as is detachment of the retina.

Treatment of uveitis usually requires medication with corticosteroids or eye drops that dilate the pupils. Sometimes more aggressive treatment is needed, such as immunosuppressive drugs, laser treatment, or surgery.

Fluoroquinolone Side Effects

Both Avelox and Cipro, the brand-name versions of moxifloxacin and ciprofloxacin, are members of a class of antibiotics called fluoroquinolones, or simply quinolones. Quinolones use a different mechanism of action from other types of antibiotics; they work directly on bacterial DNA to inhibit its function, which ultimately causes the bacteria to die.

Quinolones are the most widely prescribed antibiotics in the United States. It’s estimated that sales of quinolones will generate over $7 billion in revenue by 2019. Despite their popularity, there is a known history of fluoroquinolone side effects. Uveitis is one possible side effect; other, more notorious fluoroquinolone side effects include tendon damage and peripheral nerve damage.

Of the quinolone antibiotics, Cipro is by far the most frequently prescribed, accounting for 80 percent of all such prescriptions per year. It’s indicated for treatment of various infections of the skin, respiratory system and urinary tract, as well as infections of the bones and joints and complicated intra-abdominal infections. It’s been on the market since initial FDA approval in October 1987.

Avelox is a newer quinolone, first approved in December 1999. It’s indicated for treatment of certain respiratory, skin and abdominal infections.

So far the warning labels for both Avelox and Cipro do not include any specific mention of uveitis. It’s unknown if those labels will be amended to address the risk of uveitis from antibiotics.