Tuberculosis (TB) is an infection caused by M. tuberculosis that can cause disease in many organs, including the eye [1,2]. Ocular TB can involve any part of the eye and can occur with or without evidence of systemic TB. It generally develops following hematogenous spread from a primary focus, but in rare cases it can also occur as a primary infection following epithelial injury. Establishing the diagnosis of TB in an extrapulmonary focus is a clinical challenge.
Issues related to ocular TB will be reviewed here. Issues related to other aspects of TB, including ocular toxicities of TB medications, are discussed in detail separately. (See related topics.)
Tuberculosis (TB) is an airborne communicable disease of major public health significance in many countries. General issues related to epidemiology of TB are discussed separately. (See "Epidemiology of tuberculosis" and "Epidemiology and pathology of extrapulmonary and miliary tuberculosis" and "Epidemiology and molecular mechanisms of drug-resistant tuberculosis".)
Most TB disease involves the lungs. Ocular TB usually represents extrapulmonary dissemination of infection. The incidence of ocular TB is uncertain due to difficulties in ocular sampling for microbiology and inexact diagnostic criteria [2,3]. Prior to the era of HIV/AIDS, two prospective studies of patients with TB admitted to a sanatorium noted ocular disease incidence of 1 to 2 percent [4,5]. Since the HIV/AIDS area, prospective surveys have noted the following:
- Among 100 patients with culture-positive TB in Spain who underwent systematic ophthalmologic evaluation, ocular TB was identified in 18 percent of cases . HIV coinfection was observed in 60 percent of patients, and more than half of patients had no symptoms referable to the eye.