Optic neuritis occurs when the optic nerve, the pathway that transmits visual information to the brain, becomes inflamed, destroying the myelin sheath that surrounds the nerve.
Nerve damage that occurs in the section of the optic nerve located behind the eyeball, called retrobulbar neuritis, is most often associated with multiple sclerosis (MS). Optic nerve inflammation and swelling caused by intracranial pressure at the point where the nerve enters the eyeball is termed papillitis.
Whilst optic neuritis is most commonly associated with MS, other causes include viral or fungal infections, encephalomyelitis, autoimmune diseases, or pressure on the nerve from tumours or vascular diseases. It is most common in women between the ages of 18 and 40.
Optic neuritis usually affects only one eye and may recur several times over the course of years.
Symptoms of optic neuritis include one or more of the following:
- Blind spots, particularly with central vision
- Impaired contrast sensitivity
- Blurred or dimmed vision
- Pain with eye movement
- Sudden colour blindness
- Impaired night vision