Optic neuritis is an inflammation of the optic nerve, the bundle of nerve fibers in your eye that transmits visual information to your brain. Pain and temporary vision loss are common symptoms of optic neuritis.

Optic neuritis usually develops due to an autoimmune disorder that may be triggered by a viral infection. In some people, signs and symptoms of optic neuritis may be an indication of multiple sclerosis, a condition resulting in inflammation and damage to nerves in your brain and spinal cord.

Most people who experience a single episode of optic neuritis eventually recover their vision. Treatment with steroid medications may speed up vision recovery.

Signs and symptoms

Optic neuritis usually affects one eye, although it may occur in both eyes simultaneously.

Optic neuritis symptoms may include:

Pain. Most people who develop optic neuritis experience eye pain that’s worsened by eye movement. Pain associated with optic neuritis usually peaks within one week and then goes away in several days.

Visual loss. The extent of visual loss associated with optic neuritis varies. Some people experience severe difficulty seeing, while others might not notice any changes in their vision. Vision loss, should it occur, usually develops over a day to a week and may be worsened by heat or exercise. Vision loss is usually temporary, but in some cases, it may be permanent.

Loss of color vision. Optic neuritis often affects the perception of colors. You may notice that the colors of objects, particularly red ones, temporarily appear “washed out” or less vivid than normal.

The signs and symptoms of optic neuritis may be indications of an autoimmune disorder called multiple sclerosis. In about 20 percent of people who eventually develop multiplesclerosis, optic neuritis is the first symptom.

Causes

The complex process of sight begins when light reflecting off an object enters the clear outer portion of your eyeball (cornea) and passes through the lens, which brings the light into focus on the nerve cell layer of your eye (retina). When light hits the retina, electrical impulses are generated and carried along the optic nerve to your brain, where the impulses are converted into visual information.

The optic nerve is a bundle of nerve fibers covered by a fatty insulated material called myelin, which helps electrical impulses travel quickly along the nerve. Optic neuritis in young adults is believed to most commonly develop when the immune system attacks myelin covering the optic nerve, resulting in inflammation and damage. It’s not certain what causes your immune system to attack its own tissue. Other optic neuritis causes include:

*Infections. Bacterial infections, including Lyme disease, cat scratch fever and syphilis, or viruses such as HIV, hepatitis B, and herpes can cause optic neuritis. In addition, some infections may lead to a type of optic neuritis, called neuroretinitis, which isn’t believed to be associated with the risk of developing multiple sclerosis.

*Cranial arteritis. This is an inflammation of the lining of the arteries in your head. Inflamed cranial arteries can block blood flow to your eyes and brain, which may cause permanent vision loss or a stroke. Cranial arteritis is most likely to occur in adults age 65 years and older.

*Diabetes. Diabetes is a condition in which your body can’t make or properly use insulin, a hormone that regulates the amount of sugar in your blood. People with diabetes are at an increased risk of developing disorders of the optic nerve.

*Drugs. Some drugs have been associated with the development of optic neuritis.

Radiation therapy to your head is an uncommon cause of optic neuritis. In addition, any process resulting in inflammation or compression of the optic nerve, including tumors, nutritional deficiencies or toxins, can interfere with the nerve’s ability to conduct electrical impulses. This may cause vision loss and other symptoms that may mimic optic neuritis.

Dr. Gary S.Sy, M.D. is the medical director of Life Extension Medical Center located at The Garden Plaza Hotel ( formerly Swiss Inn Hotel) 1370 Gen Luna St., Paco, Manila. He is diplomate in gerontology and geriatrics, advocate diet-nutritional therapy, and conducts free seminar every Friday about age-related health problems. For more details e-mail at: lifeextension_drgarysy@yahoo.com.