Retina and the tubercle Bacillus: Four decades of our journey and current understanding

Tuberculosis continues to be a major pandemic with enormous public health implication. Involvement of ocular tissues in the form of tubercles, tuberculomas, panophthalmitis, and iris granulomas are well recognized as definitive manifestations of tuberculosis. For these lesions, confirmatory evidence is available in the form of demonstration of acid-fast Bacillus on Ziehl-Neelsen staining. For other retinochoroidal disorders such as central serous chorioretinopathy, retinal vasculitis, and presumed ocular tuberculosis, hard evidence about the role of Mycobacterium tuberculosis is lacking. In this review, work done at our center over the past four decades in the form of experimental animal studies, nucleic acid amplification assays and clinical studies regarding the above retinochoroidal pathologies and the tubercle Bacillus is presented. It is possible that revisiting experimental animal studies may be a way forward in the current scenario of ambiguity about the cause-effect relationship between M. tuberculosis and few of the retinochoroidal disorders.