Cytomegalovirus (CMV) optic neuritis is a rapidly blinding disease. Untreated eyes have a final visual acuity of no light perception. Treated eyes maintain visual acuity of approximately 20/100. Relapse occurs often in subjects maintained on single-dose ganciclovir and is controlled by double-dose ganciclovir. Central visual field testing is indicated to detect indolent cases of optic neuritis, because relapse can be silent with stable visual acuity and fundus appearance. Survival of patients with CMV optic neuritis is comparable to that of a matched group having CMV retinitis alone. Early recognition and therapy of CMV papillitis protect against irreversible visual loss. CMV papillitis does not carry a worse prognosis for survival than CMV retinitis alone.