Inflammation of the optic nerve, which carries signals from the light-sensitive retina to the brain
- Mainly affects young adults
- Three times more common in females
- Sometimes runs in families
- Lifestyle is not a significant factor
The optic nerve carries signals from the light-sensitive retina, found at the back of the eye, to the brain. Optic neuritis causes the nerve to become inflamed, resulting in pain and blurred vision. Usually, only one eye is affected.
Optic neuritis is most often caused by degeneration of the protective fatty sheath that surrounds the optic nerve fibres. This process, called demyelination, can be caused by a variety of conditions, including multiple sclerosis. Optic neuritis can also occur as a result of poisoning with chemicals, such as lead and methanol, or some viral infections, such as chickenpox. The condition can also occur for no obvious reason, most commonly in women in their late teens or twenties.
What are the symptoms?
Optic neuritis usually causes vision to deteriorate over hours or days. You may notice various symptoms, including:
Loss of visual detail, making it difficult to read or to recognize faces.
Loss of the central area of vision.
Pain in the back of the eye that gets worse with eye movement.
If you experience a rapid deterioration in your vision, you should consult your doctor immediately.
What might be done?
Your doctor will use an ophthalmoscope (see Ophthalmoscopy) to examine your eye and may also carry out vision tests. The optic nerve and other parts of the nervous system may be tested for signs of multiple sclerosis (see Visual evoked responses ) because optic neuritis may be the first sign of this disorder.
If you have optic neuritis, you may be given oral corticosteroids to relieve inflammation. Although vision often improves in 3–6 weeks, optic neuritis often recurs, and visual damage may be permanent. About half of all people who have optic neuritis develop multiple sclerosis within 5 years.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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