Eye Disorders: Optic Neuritis
Optic neuritis is an inflammation of the nerve that causes vision loss. The optic nerve sends vision information from the eye to the brain. Optic neuritis is usually an autoimmune process (the body's immune system attacks itself), but rarely other causes, such as infections, may be present. In some patients this will be a isolated one time event. In other patients this will be a symptom of an underlying condition, most commonly Multiple Sclerosis, which is a recurrent inflammatory disorder of the brain.
What are the symptoms?
The symptoms usually include blurry vision, side vision loss, loss of contrast (differentiating shades of gray), and/or loss of color perception. Pain, especially when moving the eye, is common in the "retrobulbar" type. The vision loss usually improves over a three to six month period, almost back to normal. However, depending on the specific situation, permanent vision loss may occur.
How is optic neuritis diagnosed?
Often the clinical presentation is characteristic enough to diagnose this condition. An MRI of the brain and optic nerve will be performed to evaluate underlying conditions, such as multiple sclerosis.
A test of cerebral spinal fluid, which is the fluid that surrounds the optic nerve and brain, is often performed by lumbar puncture.
Will I get multiple sclerosis (MS)?
A large, randomized study called the Optic Neuritis Treatment Trial (ONTT) has provided information about the natural history of optic neuritis. One's overall risk of being diagnosed with MS at 5, 10, and 15 years respectively is 30%, 38%, and 44%.
The above risks can be stratified by the result of the initial MRI. If lesions typical of MS are present, the risk increases to 37%, 56%, and 66%. If there is no MRI evidence of MS, the risks are 16%, 22%, and 23%.
How is optic neuritis treated?
The ONTT guides treatment recommendations. One finding of the ONTT is that the vision of enrolled patients improved whether or not intravenous steroids were used, but took a little longer if steroids were not used. Those using intravenous steroids had fewer conversions to multiple sclerosis for 2 years following treatment, but not thereafter. The benefit of steroids therefore has to be weighed against the potential risks when deciding therapy. The ONTT showed that steroids by mouth actually increased one's risk of getting another optic neuritis for two years.
Several studies have confirmed that systemic immunosuppressive therapy will reduce the risk of MS developing; and if MS is present, reduce the risk of recurrence and reduce disability. A neurologist administers those treatments.
The North American Neuro-Ophthalmology Society publishes a web site with good patient information on this condition.