Optic neuritis is an inflammation of the optic nerve. The optic nerve allows you to see by carrying images from your retina to your brain. The optic nerve is like a cable of electrical wires or nerve fibers. Each wire carries a part of the visual information to the brain. If some or all of the nerve fibers become inflammed and do not function properly, vision becomes blurred. With optic neuritis, the optic nerve becomes swollen and the nerve fibers do not work properly. Vision can range from near normal to very poor depending on the number of inflammed nerve fibers.
Various diseases and conditions may cause optic neuritis. In many cases, however, the cause of optic neuritis is not known. The nerve of one or both eyes may be affected. Some people, especially children, develop optic neuritis following a viral 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.
- Blurred vision in one or both eyes (especially after exercising or taking a hot bath)
- Dim vision (as if the lights were turned down)
- Abnormal color vision (dull and faded colors)
- Pain behind the eye, particularly when moving the eyes
The symptoms described above may not necessarily mean that you have optic neuritis. However, if you experience one or more of these symptoms, contact your eye doctor for a complete exam.
Optic neuritis usually occurs suddenly. If you experience any of the symptoms listed above, call your ophthalmologist. By looking in the back of your eye with an instrument called the ophthalmoscope, your ophthalmologist can see any optic nerve swelling. Optic neuritis may be confused with other causes of poor vision. Other tests such as color vision, side vision, and the reaction of the pupil to light may be performed. Ultrasound or magnetic scanning or visual brainwave recordings may be needed.