Isolated Unilateral Optic Neuritis Secondary to Presumed Ocular Tuberculosis in an Immunocompetent Adult

This case report describes tuberculous optic neuritis as the presenting feature of tuberculosis (TB) in an immunocompetent adult. A 23-year-old inmate presented with four days of painless left eye vision loss without systemic TB symptoms. Visual acuity (VA) was hand movement with relative afferent pupillary defect. Left eye light brightness was reduced, but no red desaturation. Funduscopy showed a hyperaemic optic disc and blurred disc margin, with dilated, tortuous vessels. Visual field revealed a central scotoma. Systemic examination was unremarkable. Investigation showed a normal chest X-ray, raised erythrocyte sedimentation rate, positive Mantoux, and TB Quantiferon. Lumbar puncture revealed normal opening pressure and biochemistry with negative cultures. Cerebrospinal fluid electrophoresis demonstrated oligoclonal bands, suggesting inflammation/infection. Magnetic resonance imaging showed a slightly bulky left optic nerve with T2 hyperintensity and post-contrast enhancement, suggesting optic neuritis. Anti-TB treatment improved vision to 6/6 with normal optic nerve function and a well-defined optic disc margin. Tuberculous optic neuritis requires a high index of suspicion, as corticosteroids, which are the standard treatment for optic neuritis, may worsen the outcome without anti-tubercular treatment.