Optic nerve multiple sclerosis symptom. Coloured coronal magnetic resonance imaging (MRI) scan of the brain of a 32-year-old woman with vision problems. The scan has revealed a problem with the right optic nerve (round area, centre left). This may be retrobulbar neuritis, a form of optic neuritis that is often an early sign of multiple sclerosis. Both conditions are caused by demyelination of the nerves. This MRI scan is an example of a special technique known as STIR (short tau inversion recovery), plus the use of gadolinium as a contrast medium.