Optic Nerve Inflammation
What is Optic neuritis?
Optic neuritis is an inflammation of the optic nerve causing sudden visual loss in part of the visual field (total area an individual can see while looking straight ahead). Inflammation of the optic nerve may be caused by a wide variety of diseases. They include demyelinating diseases (loss of the optic nerve's protective myelin sheath); viral infections, including infections that have spread from a nearby structure; current infections or inflammation located elsewhere in the body; decreased blood supply to the nerve; tumors or cancers; nutritional and metabolic disorders; and poisoning or exposure to toxic chemicals. Direct injury to the optic nerve can also cause neuritis.
One form of optic neuritis, retrobulbar neuritis, is associated with multiple sclerosis. The nerve inflammation occurs far enough behind the optic disk (point in retina where optic nerve enters eyeball) that early changes of the optic disk are not evident. Although the individual's vision is markedly reduced, early disk changes may not be visible upon ophthalmoscopic exam (using an instrument that allows examination of the interior of the eye).
Optic neuritis affects individuals between 20 and 40 years of age. More than 75% of those affected are women, and 85% are Caucasian.
How is it diagnosed?
History: Individuals may complain of pain in the region of the eye that worsens with specific eye movement. Eyes are tender when touched. Visual defects occurring over the first few hours gradually increase during the next several days. Scotomas, the most common visual defects, are island-like blind gaps. They are usually circular, but vary widely in size and density).
Physical exam: Pupil response to light may be slowed. The optic may at first appear normal on ophthalmoscopic exam. Later exams may reveal that the edge of the optic disk has become blurry, and finally swollen as the disease progresses. There may be small areas of bleeding (hemorrhages) near the optic nerve.
Tests: Vision tests may include evaluation of visual acuity and of total visual field.
How is Optic neuritis treated?
Anti-inflammatory drugs (corticosteroids) may be injected into the eye, given by mouth, or both. Although treatment with corticosteroids may aid the return of vision, they seem to have little effect on the long-term outcome of the inflammatory process.
Retrobulbar neuritis is treated with corticosteroids, but chronic cases of may also require intensive immunosuppression therapy (in an attempt to suppress the body's immune response).
What might complicate it?
In severe cases, inflammation may spread to a large portion of the optic nerve temporarily causing complete blindness. Retrobulbar neuritis can progress to multiple sclerosis, especially in women with certain risk factors.
Simple optic neuritis usually resolves without treatment within a few weeks. Full recovery occurs in 65% of all cases. Some cases, however, result in small vision defects. Other cases progress into optic atrophy (wasting or degeneration of the optic nerve) and may result in permanent blindness. Although retrobulbar neuritis responds to treatment, each recurrence produces further visual loss and may eventually lead to optic nerve atrophy that results in permanent blindness. If caused by poor circulation, optic neuritis will often not improve.
Psychiatrist or psychologist.
Last updated 6 October 2011