Multiple Sclerosis: What is Optic Neuritis?

Optic neuritis, or inflammation of the optic nerve, is the most common visual disorder associated with multiple sclerosis (MS), and it's often a person's first symptom of MS. With optic neuritis, you can have any or all of the following problems:

  • Vision loss in one eye (Even though loss in both eyes simultaneously is rare, it isn't uncommon for visual changes in the other eye to occur during subsequent episodes of optic neuritis.)

  • Blind spots in the center of the visual field

  • Faded or washed-out color vision

  • Reduced contrast sensitivity, which makes it difficult to see things that don't contrast sharply with their background (for example, gray print on blue paper)

  • Pain behind the affected eye

  • Visual phenomena, such as flashes of light

  • Slowed response of the pupils to changes in light

Your symptoms are likely to worsen over the course of a few days or weeks and then gradually improve. Some people recover within a month while others need up to a year or more. Most people regain normal or near-normal vision, but you may find that the quality of your vision, including contrast sensitivity and color vision, remains somewhat off. Keep in mind that any of the changes can affect your daytime and nighttime driving.

Optic neuritis may resolve on its own, meaning that patience is all you need. However, a regimen of high-dose, intravenous corticosteroids — for example, a three- to five-day course of Solu-Medrol (methylprednisolone), which is sometimes followed by several days of a tapering dose of oral steroids — can speed your recovery.

So, the question becomes whether or not to treat. Because corticosteroids don't have any long-term benefit, and because they can have unpleasant side effects, waiting it out is an option. If, however, your safety or ability to function is being compromised by vision changes, MS specialists recommend treatment.

Most specialists also recommend treatment if optic neuritis is your first MS symptom because IV corticosteroids given at that time can delay a second demyelinating event in some people — and therefore the diagnosis of MS. In the short-term, we suggest marking doorways, stairs, and steps with high-contrast tape, turning up the lights as high as you can, and by wearing glasses with polarizing lenses.

Inflammation of the optic nerve can also occur without causing any symptoms. In other words, the damage occurs to the optic nerve without you noticing any changes in your vision. That's why the visual evoked potential test can be useful in making the MS diagnosis. This test can detect evidence of demyelination even though you're unaware of the problem.

Optical coherence tomography (OCT) is another test that can evaluate the health of the optic nerve. OCT is a painless, noninvasive test that uses light to measure the diameter of the optic nerve and lets the doctor know what, if any, damage has occurred from previous optic neuritis attacks.

The symptoms of optic neuritis can flare up when your body is overheated, whether it's from exercise, hot, humid weather, or a fever. This temporary flare-up — called Uhthoff's phenomenon — is an example of a pseudoexacerbation that can occur when your body is overheated, meaning the symptoms resolve as soon as your body temperature returns to normal.

Because it only takes a small elevation in core body temperature to cause this phenomenon in some people, keep yourself cool with air conditioning and cold drinks, particularly when exercising or during periods of hot weather.

MS vision problems are treated by your neurologist or a neuro-ophthalmologist (a physician who specializes in eye problems that are neurologic in origin) rather than your regular eye doctor. Whether you have MS-related eye problems or not, however, you need to continue receiving standard eye and vision care from your optometrist or ophthalmologist.

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