Optic neuritis is a demyelinating inflammatory condition affecting the optic nerve. It usually affects young women and can be the first sign of multiple sclerosis.
It causes a variable degree of visual disturbance (acuity) which usually comes on quite rapidly and is usually central (scotoma). Commonly, it causes a change in colour vision, chiefly red desaturation.
On examination of the fundus, the picture may be normal, or the patient may have a swollen optic disc and/or relative afferent pupil defect.
Optic neuritis is normally self-limiting and no treatment will aid its cure. However steroids may be useful (in potential MS patients) to reduce the recurrence of ON or slow the onset of MS.