Optic neuritis is the inflammation and swelling of the optic nerve. It is also called acute demyelinating optic neuritis. The optic nerve connects the back of the eye to the brain and transmits signals allowing sight.
Its exact cause is unknown but is thought to arise from the body’s immune system attacking the nerve tissue, especially the protective myelin layer surrounding the nerves. This can be triggered by viral infections like encephalitis, mumps, measles or flu.