Optic Neuritis

Overview

Optic neuritis refers to inflammation of the optic nerve. While the cause may often be unknown, the disease most commonly associated with optic neuritis is multiple sclerosis (MS). It is not uncommon to have an episode of optic neuritis prior to being diagnosed with MS. In fact, optic neuritis is often the initial sign of MS.

Most patients with optic neuritis experience a sudden onset of decreased vision along with pain around the eye, especially when moving the eye. Optic neuritis usually affects only one eye and may be a recurring problem with certain diseases such as MS.

Signs and Symptoms

The following symptoms of optic neuritis may not occur in all cases; however, they are the most common problems associated with the condition.

• Pain with eye movement (more than 90% of patients)
• Tender, sore eye
• Mild to severe decrease in central vision
• Decreased peripheral vision
• Dull, dim vision
• Reduced color perception
• Headache
• Decreased vision following exercise, hot bath or shower (activities that elevate body temperature)

Diagnosis

The doctor takes several factors into consideration when diagnosing optic neuritis. The problem may not always be readily apparent by examining the optic nerve, so special attention is paid to the patient's symptoms. Other tests that are performed to aid in the diagnosis include a visual field, color vision, and MRI of the brain.

Treatment

The Optic Neuritis Treatment Trial (ONTT) showed that treating patients with intravenous steroid medication (but not oral steroids) could reduce the risk of developing MS for a short period of time. This was only true, however, for a certain subset of patients. The treatment with intravenous steroids also enhanced visual recovery, but did not ultimately improve it. Fortunately, vision tends to return to near normal levels in most patients over several weeks, even if untreated.

A second study, the Controlled High-Risk Subjects Avonex Multiple Sclerosis Prevention (CHAMPS) Study has also yielded important new information. Patients treated with weekly intramuscular injections of Avonex had a 44% lower rate of developing clinically definite MS than those treated with placebo. Treated patients also had a lower rate of new lesions on MRI. Since optic neuritis is often the first sign of the possibility of having MS, ophthalmologists play a pivotal role in the diagnosis and timely treatment of this disease.