Optic neuritis is an inflammation of the optic nerve, which makes objects appear blurred. The optic nerve transmits the sensation of sight from the eye to the brain.
The optic nerve consists of 1.2 million separate tiny nerve fibres. Each fibre carries a part of the visual information we see to the brain. If some or all of the nerve fibres are inflamed and are not working properly the vision becomes blurred.
When you have optic neuritis the nerve tissue becomes swollen and the nerve fibres do not function properly. Depending on how many nerve fibres are involved, vision may be very poor. If, however, only a few fibres are involved, vision is nearly normal.
There are quite a few diseases and conditions that cause optic neuritis, such as a viral infection like mumps, measles or colds that especially effect children. Optic neuritis also is part of Multiple Sclerosis (MS) which is a disease of the central nervous system.
To diagnose optic neuritis your ophthalmologist needs to have a careful description of the symptoms. A complete medical eye examination will be done. An instrument called the ophthalmoscope will be used to look into the eye to see if there is a swelling of the optic nerve where it enters the back of the eye. Medical diagnosis is very important and should be done accurately, as optic neuritis can be confused with many other causes of poor vision. Other tests also may be done such as colour vision, side vision, MRI scanning, and the reaction of the pupil to light.
If the optic nerve is not affected by optic neuritis, the nerve may appear normal. However, the nerve may have been affected further back near the brain. Further damage may be prevented if the cause can be found and treated early enough.
Most people who have optic neuritis do not have to be treated to recover normal vision. However high doses of intravenous corticosteroids may be beneficial in restoring vision more rapidly, although optic neuritis might recur in the same eye or the other eye.
Regular medical eye examinations are important for everyone, as eye disease can occur at any age. Often the patient does not realise symptoms unless the disease has done damage. Therefore, if diagnosed and treated early, most blindness is preventable.