Tuberculous Optic Neuropathy

Tuberculosis is an infection caused by the bacterium Mycobacterium tuberculosis and is most commonly acquired by the inhalational route by which the infectious agent enters into the lungs and the primary infection is established. These infected individuals run a 10% risk of reactivation of the infection which can manifest as either pulmonary or extrapulmonary disease. The hematogenous or lymphatic spread can result in involvement of the other sites. Ocular involvement is reported in 6.8% of patients with pulmonary tuberculosis. Till date, very less has been reported in the literature about the optic nerve involvement in tuberculosis. However, the advent of antimicrobial agents against Mycobacterium tuberculosis has led to marked improvement in the patient survival, and the reports of tuberculous optic neuropathy in the literature have been on rise since then. Tuberculous optic neuropathy entails a host of optic nerve involvements which may follow direct infection with the Mycobacterium tuberculosis, bacille Calmette-Guerin vaccination, or as a result of the hypersensitivity reaction. This bewildering array of manifestations of tuberculous optic neuropathy comprises of optic neuritis, retrobulbar neuritis, papillitis, neuroretinitis, papilledema, and optic nerve tubercle. In this chapter, we try to describe the various types of tuberculous optic nerve involvement, clinical features, diagnostic and treatment modalities, and visual outcomes in these patients.