Retrobulbar Neuritis

What Is It?

Retrobulbar neuritis is a form of optic neuritis in which the optic nerve, which is at the back of the eye, becomes inflamed. The inflamed area is between the back of the eye and the brain. The optic nerve contains fibers that carry visual information from the nerve cells in the retina to the nerve cells in the brain. When these fibers become inflamed, visual signaling to the brain becomes disrupted, and vision is impaired.

Retrobulbar neuritis can be caused by a variety of conditions, including:

• Infections such as meningitis, syphilis, Lyme disease and various viral illnesses
• Multiple sclerosis
• Tumors
• Exposure to certain chemicals or drugs
• Allergic reactions

However, in many cases, the cause is unknown. Vision loss can be minimal or the disease can result in complete blindness.

The average age of people who develop optic neuritis is 32. Most are female, and the vast majority also have pain when they move their eyes. Retrobulbar neuritis often is an early sign that someone has multiple sclerosis. Between 20 percent and 40 percent of the 25,000 people who develop optic neuritis in the United States each year will develop multiple sclerosis within 10 years.

Symptoms

Symptoms usually worsen for two weeks and then stabilize. However, the course of the illness varies greatly. Most cases show some improvement over time, although complete recovery is rare. Optic neuritis usually affects only one eye, but both eyes may be affected. Common symptoms include:

• Blurred or dimmed vision
• A blind spot at or near the center of vision
• Color "wash-out" so that colors are less rich
• Pain with eye movement
• Tenderness of the eye to touch or pressure
• Complete blindness in the affected eye

Diagnosis

A doctor will use an ophthalmoscope to examine the back of the eye, particularly the optic disc. This is where the optic-nerve fibers concentrate before exiting the eye to extend back toward the brain. In the early stages of retrobulbar neuritis, the optic disk appears normal. Later, it may become pale.

The pupil normally becomes smaller (constricts) in response to light. In retrobulbar neuritis, this response often is reduced in the affected eye. The doctor also will test your visual acuity, which frequently is impaired in the affected eye. The doctor will test your side vision because, in all cases of retrobulbar neuritis, a scotoma, a blind or dark spot in the visual field, will be present. The doctor also may search for associated conditions, such as infection or multiple sclerosis, after a detailed discussion about other symptoms and a complete physical examination.