Ocular Tuberculosis

Tuberculosis is an infection caused by Mycobacterium tuberculosis, which can manifest in multiple organs, most commonly the lungs, but can also affect the eye. The unique aspect of infection by M. tuberculosis is the complex interplay that occurs with the host immune system, leading to chronicity of the infection. When initial infection occurs, it promotes a type IV hypersensitivity reaction leading to the recruitment of alveolar macrophages that attempt to phagocytose and destroy the bacilli. However, when they fail, the bacteria multiplies within the intracellular matrix and bursts out, leading to the recruitment of more macrophages and a domino effect ensues. Lymphocytes are then recruited and form a granuloma to contain the infection. In immunocompetent individuals, this can lead to resolution of infection or indefinite latency. In the setting of immunocompromised patients, the disease can progress to active TB.