Tubercular Retinitis and Retinal Vasculitis: Manifestations of a Shared Disease Spectrum

Isolated retinal involvement in ocular tuberculosis (TB) is not well understood and remains largely underreported. TB retinal lesions can be classified into two broad categories: retinal vasculitis and isolated retinal granuloma. TB retinal vasculitis is the more recognized phenotype and may present with perivascular infiltrates alone or alongside other ocular signs such as subvascular lesions, focal vascular tortuosity, and occlusive vasculitis. These additional signs are crucial for diagnosing TB retinal vasculitis in TB-endemic regions. However, isolated retinal granulomas due to TB are rarely documented and poorly characterized. In this review, we have described the various clinical phenotypes of retinal TB, including a multimodal overview of an isolated intraretinal granuloma. We propose that TB retinitis and retinal vasculitis are part of a disease continuum of retinal TB. To support our hypothesis regarding retinal TB, we draw inferences from historical data derived from histopathological examinations of the eye as well as clinical and experimental studies on cerebral TB vasculitis. We have also reviewed other sites of TB vasculitis, such as the skin and major vessels, including the aorta. Understanding TB vasculitis in the brain and other organs could potentially elucidate not only the pathogenesis of retinal TB but also the diagnosis and management of this condition.