OCULAR TUBERCULOSIS

In recent years tuberculosis has reemerged as a serious public health problem, raising the possibility that tuberculous eye disease may also become more prevalent. The predominant route by which tubercle bacilli reach the eye is through the bloodstream, after infecting the lungs. The pulmonary loci might not be evident clinically or radiographically. The most common manifestation of ocular tuberculosis in patients with pulmonary tuberculosis is choroiditis. Retinal periphlebitis is rarely caused by direct invasion of the retina by tubercle bacilli. Retinal tuberculosis is usually, but not always, secondary to an underlying choroiditis. Tuberculoprotein hypersensitivity may have a role in the pathogenesis of phlyctenulosis and Eales' disease. Both ocular and orbital tuberculosis are usually unilateral. Skin testing should be performed in selected patients based on the clinical presentation and/or a history of exposure to tuberculosis. The specificity of the PPD skin test for Mycobacterium tuberculosis increases with larger skin reactions and with a history of exposure to an active case of tuberculosis. Because of the potential for serious drug toxicities, empiric treatment with antituberculous chemotherapy should be reserved only for those cases that have an identifiable risk of tuberculous disease.