Tuberculosis in Eyeballs? Here’s What You Should Know About the Rare Condition

When Amit Reddy, MD, assistant professor of ophthalmology at the University of Colorado School of Medicine, sees a patient for uveitis, there are a bevy of factors that could be causing the inflammatory condition. In rare instances it can even be bacteria Mycobacterium tuberculosis.

Tuberculosis (TB) typically attacks the lungs, but it can affect other parts of the body, too. If it reaches the eyes, the patient may experience uncomfortable symptoms that are consistent with uveitis: blurred vision, floaters, swelling, and general discomfort.

“Fortunately, we don't see ocular TB in Colorado so much,” Reddy says. “Part of that is because the TB rates in Colorado generally are quite low, likely related to the high altitude. Interestingly, before TB antibiotics were available, TB ‘sanatoriums’ were frequently located in areas at high elevation.”

Still, cases do occasionally end up in the care of Reddy and his colleagues. In 2023, a paper authored by Julia Xia, MD, a current uveitis fellow at the Sue Anschutz-Rodgers Eye Center, and colleagues found that the center had a 4% positivity rate of TB. However, most of those positive tests were coincidental and unrelated to the patient’s uveitis disease process.

Having a positive TB test doesn’t necessarily mean a person has an active infection in their eyes, Reddy explains, but that the patient has previously been exposed to tuberculosis.

Here, Reddy explains ocular tuberculosis, why it can be difficult to spot, and the treatments doctors use to address the infection and relieve the symptoms.

How does tuberculosis end up in the eyes?

When you’re exposed to TB, it usually goes to the lungs. It can enter the bloodstream and then it can go anywhere in the body. We’re not exactly sure how it ends up in the eyes of some patients and not others, but it may have something to do with the way the patient’s immune system responds to the TB. In the vast majority of people who have been exposed to TB, the immune system controls the infection and it does not cause any problems.

In the eyes, TB typically goes into the layer behind the retina called the choroid. That’s the most vascular area of the eye.

What are the symptoms of ocular tuberculosis and how do you know if a patient has it?

Sometimes the patient has whole-body symptoms of TB, such as cough, fever, and weight loss. But in many cases of ocular TB, we are not able to find signs of TB causing problems in the rest of the body.

The ocular symptoms can be subtle. Many patients experience floaters or blurry vision. Classic ocular TB doesn’t necessarily have significant eye pain or redness. Instead, they’re more likely to experience vision changes.

It sounds like a difficult condition to diagnose. What’s the process for that like?

In any new patient with eye inflammation, we always evaluate for syphilis with a blood test and obtain a chest x-ray to screen for an autoimmune disease called sarcoidosis.

The chest x-ray helps screen for an active TB lung infection, and we can obtain TB testing with a blood test if we are starting medications that will suppress the patient’s immune system. This is because these medications could cause re-activation of a TB infection if the patient had been previously exposed.

Patients may also get a TB test if we suspect the ocular inflammation could actually be caused by TB. The Standardization of Uveitis Nomenclature group has utilized machine learning technology to analyze what appearances of ocular inflammation may be consistent with a TB infection. This has been helpful in determining which patients really need a TB test done.

Is ocular TB contagious?

If it’s just in the eyes — or in other places other than the lungs — generally no. The contagious aspect of TB comes when it’s active in the lungs and the person coughs and it spreads.

What is treatment like for ocular tuberculosis?

If we believe there's uveitis that's actually related to the positive TB test, we treat with anti-TB antibiotics. These drugs can have significant side effects, so it’s important we only use them when necessary.

We also frequently use steroids like prednisone, which is anti-inflammatory, because there’s thought to be some component of damage that’s coming from the immune system responding to the TB.

For most people, should ocular TB be a concern?

Not so much in the U.S. or in Colorado. Most cases we see are in people who grew up in a TB endemic area like southeast Asia or Africa, where there are still relatively high rates of TB. If you know you’ve been exposed to TB and you’re having vision changes, floaters, or any kind of eye pain, it would be a good idea to get an eye exam.