12/05/2000 - Tuesday
THE FAMILY DOCTOR
Dr. Allen Douma. TRIBUNE MEDIA SERVICES, INC.
Q. I am 50 and have developed a condition my doctor calls optic neuritis. I suddenly lost sight in my right eye. All my CAT scans and blood work are negative. I am not overweight and have no hormonal problems. - N.M.
A. I hope your optic neuritis is not serious and that your vision problems are gone by now.
Optic neuritis is an inflammation of the optic nerve, the nerve that conducts visual signals from the eye to the brain.
Because the damage associated with optic neuritis is almost always in only one of the optic nerves, the visual symptoms are confined to one eye.
Optic neuritis develops suddenly and may get worse for a few days after onset. Eye movement can be painful. Severity of vision loss can range from 20/30 vision to almost total blindness. Often only a section of the visual field is diminished, and loss of color perception is common.
Fortunately, vision returns to normal or almost normal within two to eight weeks in about half the cases of optic neuritis, but blurring in the center of the eye and diminished color perception may remain.
Relapses do occur, and each episode tends to worsen the long-term effects.
Destruction of sufficient optic nerve fibers can result in permanent vision problems.
This condition is often caused by multiple sclerosis and is associated with the process of demyelination. In fact, about three-fourths of people with unexplained optic neuritis will be diagnosed with MS within 15 years.
The myelin sheath is a layer of insulation around nerve fibers. The sheath allows electrical impulses to be transmitted intact along the nerve fibers.
When the myelin sheath is damaged, impulse transmission is interrupted, resulting in neurological problems.
Other causes of optic neuritis include viral infections, inflammation of local arteries, poisons, tumors, allergic reactions, meningitis, syphilis and arteriosclerosis.
Treatment of optic neuritis begins with identifying and treating the cause.
I presume your doctors are doing this detective work.
Corticosteroids are sometimes given to treat the inflammation. Visual recovery can be accelerated by intravenous administration of methylprednisolone followed by oral prednisolone, but there can be side effects. The decision to recommend this or other treatment depends on the degree of vision loss in the affected eye, the condition of the other eye, a person's visual needs and his or her susceptibility to the side effects.
In any case, anyone with sudden loss of vision should immediately consult a medical specialist for an evaluation.
The Family Doctor is a health education column and is not a substitute for medical advice from your physician. Allen Douma received his medical degree from the Medical College of Virginia and spent 12 years in clinical practice.
He has written, edited and advised on numerous medical publications, including the American Medical Association's Family Medical Guide. Send questions to The Family Doctor, Discovery section, Newsday, 235 Pinelawn Rd., Melville, N.Y.
11747-4250. Questions cannot be answered personally.