The optic nerve is the nerve of vision. It carries images of what we see coded as electrical impulses, from our eye to our brain. The optic nerve is like a cable of electrical wires, and consists of about 1,200,000 separate tiny wires, or nerve fibers. Each of these carries a part of the information. If some or all of the nerve fibers do not do their job, our vision becomes blurred.

Optic neuritis is the medical term used to describe an inflammation of the optic nerve. The nerve tissue becomes swollen and red, and the nerve fibers do not work properly. If many of the nerve fibers are involved, the vision may be very poor, but if the optic neuritis is mild, vision is nearly normal.

What Causes Optic Neuritis?

Many diseases and conditions may cause optic neuritis, which may affect the optic nerve of one or both eyes. Some people, especially children, develop optic neuritis following a virus illness such as mumps, measles, or a cold. In others, optic neuritis may occur as a sign of a neurologic disease affecting nerves in various parts of the body. In a rare condition called Leber's optic neuropathy, which often runs in families, a special kind of optic neuritis may appear in both eyes within a short span of time.

Most of the time, however, we cannot discover a cause for optic neuritis. In those cases, we call the neuritis idiopathic, meaning that no particular cause can be found.

What Are The Symptoms And Signs Of Optic Neuritis?

Optic neuritis usually comes on suddenly, and the patient notices vision is blurred in one or both eyes. The vision is also dim, like somebody turned down the lights, and colors may appear to be washed out. There may be pain in the area of the eye socket, especially when moving the eyes. The vision may continue to get worse over a week or two, and may seem worse after exercising or a hot bath.

A careful description of these symptoms is important to your medical doctor in the diagnosis of optic neuritis. Your ophthalmologist will also perform a complete medical eye examination.

Since the optic nerve enters the back of the eye where it appears as a small disc, your ophthalmologist can examine it by looking in your eye with a special instrument called an ophthalmoscope. Swelling of the optic nerve may or may not be visible depending on whether the optic neuritis is affecting the optic nerve near the eyeball.

Since optic neuritis can be confused with many other causes of poor vision, an accurate medical diagnosis is important. If a cause can be found and treated, further damage may be prevented. Ultrasound, CT scans, or visual brain wave recordings might be ordered. Other tests which may be performed by your ophthalmologist include color vision, side vision, and pupil reactions to light.

How Is Optic Neuritis Treated?

Unfortunately, there is no good treatment for optic neuritis. Cortisone-like medications (steroids) can be prescribed, but in most cases they are not effective. Fortunately, most patients with optic neuritis improve without treatment. In some cases, the vision may return to normal. In other cases, good but incomplete improvement occurs. A few patients fail to recover normal vision, especially those with special conditions.

Reference: American Academy of Ophthalmology