Investigations
No investigations are required to diagnose optic neuritis. It can be diagnosed clinically.
The Visual Evoked Potential (VEP) confirms optic nerve affection. It is an electro diagnostic modality which reveals the visual potential of the brain when light is shown into the eye. The wave form is typically delayed in a patient of optic neuritis. The delay in the waveform remains so even after complete visual recovery.
Magnetic Resonance Imaging (MRI) brain is required to diagnose multiple sclerosis, an autoimmune disease which affects not only the eye (optic neuritis, internuclear ophthalmoplegia, cranial nerve palsies) but also the brain and the spinal cord and its functions.
MRI is done with gadolinium (a dye) enhancement to reveal the demyelinating plaques characteristic of multiple sclerosis.
Blood tests are done to rule out other causes of optic neuropathy.