Optic neuritis is inflammation of the optic nerve, caused by damage to and loss of the protective sheath (myelin) surrounding this nerve that is so vital for good vision. Demyelinating optic neuritis is another term for this eye condition.
Vision symptoms from optic neuritis can include blurring and blind spots. You also may notice distorted vision, reduced color vision and pain when you move your eyes. These types of symptoms may precede vision loss due to optic neuritis.
Optic neuropathy more generally describes optic nerve abnormalities or damage, including from causes such as blocked blood flow or toxic exposure.
What Causes Optic Neuritis?
Optic neuritis usually occurs in adults younger than 45 and affects more women than men. The condition is common in people who have multiple sclerosis (MS), which occurs when the body's own immune system attacks and destroys protective nerve coverings. Besides affecting eyesight, related nerve damage in MS can lead to loss of mobility and sensory functions, along with other debilitating conditions.
Other causes of optic neuritis and neuropathy include:
- Infections such as toxoplasmosis
- Ocular herpes
- Other viral infections
- Sinusitis
- Neurological disorders
- Leber hereditary optic neuropathy, an inherited form of vision loss that affects mostly males in their 20s or 30s
- Nutritional deficiency
- Toxins, including alcohol and tobacco
During an eye exam, your eye doctor will look for signs of optic neuritis by conducting tests to evaluate whether you have reduced vision.
Your eye pressure will be measured, and your pupils will be dilated to provide a better view of the eye's interior structures, including the optic nerve and retina.
When optic neuritis is present, the pupil always appears abnormal (afferent pupillary defect). This means the pupil actually dilates instead of constricting in the presence of bright light. The optic nerve in this disorder may appear normal or swollen. A visual field test also may be needed to determine if you have peripheral vision problems.
A person with optic neuritis usually undergoes an MRI of the brain, to look for central nervous system lesions.
By Chris A. Knobbe, MD
