Optical coherence tomography (OCT) of the nerve fiber layer from a 42-year-old patient who presented with painful vision loss OS suggestive of optic neuritis. Examination showed temporal pallor of both optic discs. Magnetic resonance imaging showed enhancement of the retrobulbar optic nerve and multiple demyelinating lesions. Cerebrospinal fluid analysis confirmed the diagnosis of multiple sclerosis. OCT on presentation showed thinning of the temporal nerve fiber layer OD and OS suggestive of old optic nerve damage from previously undiagnosed optic neuritis.