One of the first things we do when we see a case of uveitis is to rule out an infectious cause. In Asia, tuberculosis (TB) is one of the common infections that lead to uveitis. TB (Mycobacterium tuberculosis) can live in almost any tissue in the body . In the eye it can affect both the front and back of the eye causing anterior and posterior uveitis . The TB organism reaches the eye through the blood stream. The chest X-ray may be normal and patients may have no cough. Despite receiving the BCG vaccination, many can still have TB in the eye.
How do we diagnose TB in the eye?
A special skin test called the Mantoux test or a quantiferon test is usually done as an indirect method to diagnose tuberculosis of the eye. If a person has a cough we usually send the sputum or phlegm for testing to detect the TB germ . Unfortunately in the eye it is sometimes difficult to obtain the fluid specimens from the eye and we still rely a lot on examination findings and indirect tests. Sometimes vitrectomy surgery can be done to get specimens from the eye. Once the diagnosis is made patients respond well to treatment with antituberculous drugs in combination with steroid treatment. The minimum duration of treatment is 6 months but can go on to 18 months. A reassuring fact is that TB in the eye is not contagious.