When Should I Be Suspicious of Tuberculosis and What Testing Is Useful?

Although ocular tuberculosis (TB) is rare in the developed world, an increase in the migration of people from regions of endemic TB has led to a re-emergence of this ocular infection in the United States and other western countries and to a re-emphasis on its recognition. The use of polymerase chain reaction (PCR) and gamma interferon release assays has helped make possible the early diagnosis of intraocular TB in both endemic and nonendemic regions of world and has helped define the clinical features of ocular TB. 1-5 In endemic and nonendemic countries, a mycobacterial ocular infection can manifest with diverse clinical features, primarily depending on the lodgment of the bacteria in the ocular or ocular adnexal structures. The route of such bacterial dissemination is usually from the lung to the eye. In more than 90% of exposed individuals, the bacteria can remain dormant in the lung or in extrapulmonary organs, including the eye. Microbial reactivation at these sites occurs at a later period, usually months to years, leading to the clinical manifestation of the infection. In the eye, however, such extrapulmonary infection usually presents in the absence of clinically apparent pulmonary or other extrapulmonary disease. 2 Of the various clinical manifestations of ocular TB, the most common presentation is an intraocular inflammation/ uveitis in the form of anterior, intermediate, posterior (Figure 17-1), or panuveitis; choroidal or subretinal mass; retinal periphlebitis or vasculitis; optic neuropathy; and sclerouveitis.