Optic neuritis is a serious eye condition that causes a loss of vision and may be a warning about more serious systemic disease. When the optic nerve is inflamed, vision is affected.
This condition can occur at any age. In children, it often occurs in both eyes at the same time. In adults, it is more common to affect only one eye. Optic neuritis is more common in women than men. The average age that an adult develops the disease is 31 years.
Optic neuritis is associated with other medical conditions. People who develop optic neuritis may go on to develop multiple sclerosis (MS). The risk of developing MS is greatest in the first two years after a bout of optic neuritis. About 40% of people with optic neuritis will go on to develop MS. Optic neuritis and multiple sclerosis are called "demyelinating diseases." Myelin is a substance that acts like insulation around a nerve. Just as insulation on an electric wire protects the wire, myelin protects nerves. When a nerve loses its insulation, the messages in the nerve slow down. This slowing affects the ability of the nerve to do its job. Myelin is destroyed by these diseases, resulting in nerve disorders that cause troubles with vision and many other organ systems.
When someone develops optic neuritis, he or she notices several changes over a period of 2-5 days. The vision in the affected eye becomes blurred. Color vision is lost — images appear as shades of gray. There may be pain with movement of the eye. There may be blind spots in the field of vision. Vision can get so bad that the person cannot even see light. An eye doctor will be able to see abnormalities in the way the pupil works and sometimes, see swelling and inflammation of the head of the optic nerve, inside the eye.
Optic neuritis usually gets better, even without treatment. In three quarters of patients, the vision starts to improve to some degree, in a few weeks. It can take several months for it to get to its maximum level. The vision after a bout of optic neuritis is often, nearly as good as it was before.