The Link Between Optic Neuritis and MS

When you think of common symptoms of multiple sclerosis (MS), difficulty walking, numbness, or muscle weakness may come to mind—but those aren’t the only ways MS can manifest. Many people with MS also have eye problems, including a little-known issue called optic neuritis. It may be a new term to you, but for people with multiple sclerosis, optic neuritis is surprisingly common.

In fact, optic neuritis is one of the most prevalent eye complications associated with MS, affecting 50% of all MS patients at some point in their lives. (Other eye issues like nystagmus and diplopia also affect MS patients but are generally less common.) Optic neuritis can happen for reasons other than MS, but it’s an initial sign of the disease in some 20% of patients, says neurologist Steven L. Galetta, M.D., a professor and department chair of neurology at NYU Langone Health in New York City.

MS is known to damage the central nervous system (including the eyes, brain, and spinal cord). This happens when the condition tricks your body into attacking your nerve cells, specifically targeting what are known as “myelin sheaths” that surround the cells and are essentially a protective covering of the nerve fibers. This is known as “demyelination.”

“MS and optic neuritis are intimately linked because the primary attack [in MS] is against myelin or the insulation of the axons,” Dr. Galetta further explains. “Both the brain and optic nerve have similar proteins that make up their myelin and are subject to this type of autoimmune attack.”

When this happens to the optic nerve, its cells, and their myelin sheaths, the damage makes it harder for the optic nerve to do its job and can cause optic neuritis.

Optic neuritis is the swelling of the optic nerve. The optic nerve enables our sight by sending messages from the eyes to the brain, and when it’s inflamed and irritated from optic neuritis, it can’t properly send those messages. This condition is officially known as an acute inflammatory demyelinating disorder of the optic nerve, while MS itself is a demyelinating disorder of the central nervous system.

Curious to learn more? Here’s what the experts have to say about the relationship between MS and optic neuritis, as well as the symptoms, diagnosis, and treatment for this eye disorder.

You may have recently noticed eye trouble and wonder if it could be one of the symptoms of MS, Or maybe you’ve already been diagnosed with MS and want to know what to look out for with regard to optic neuritis. Here are the main symptoms of this eye condition, according to the American Academy of Ophthalmology (AAO) and The National Multiple Sclerosis Society:

• Blurry vision

• Colors appearing dull, gray, and/or faded (especially red and pink)

• Dim vision, as if someone turned down the lights, in the center of your vision

• Loss of vision

• Pain in the back of your eye socket

• Pain when you move your eyes

You can experience these symptoms in one eye (which is most typical), or both. Symptoms may appear suddenly, or gradually over a few days.

“In most cases, it’s not total loss of vision,” explains Howard R. Krauss, M.D., a surgical neuro-ophthalmologist at Providence Saint John’s Health Center, Pacific Neuroscience Institute in Santa Monica, CA. It does tend to worsen over time though. “It’s got a progression,” Dr. Krauss says. “Very often, patients will awaken or be aware of something off with their vision. They’ll compare the vision in their two eyes and notice that one eye may be a bit blurrier than the other eye. As the hours go by, or the next day, it’s significantly worse.”

MS isn’t the only condition that causes optic neuritis, though. Other conditions can be associated with inflammation of the optic nerve. For instance, neuromyelitis optica (severe inflammation that harms both the optic nerve and spinal cord) and an antibody disorder known as myelin oligodendrocyte glycoprotein (MOG) can trigger Mayo Clinic notes.

Here’s a full possible list of reasons you could find yourself with an optic neuritis diagnosis:

Infections and Diseases

Common—and less common—infections can trigger the onset of optic neuritis. These are some infections your doctor may explore with you:

• Cat-scratch fever

• Herpes

• Lyme disease

• Measles

• Mumps

• Syphilis

In addition to infections, other types of disorders can contribute to symptoms of optic neuritis. These are a few to consider:

• Behcet’s disease

• Inflammatory bowel disease

• Lupus

• Neuromyelitis optica spectrum disorder

• Sarcoidosis

Drugs and Toxins

And finally, certain medications and/or chemical compounds are associated with the development of optic neuritis in some people. Talk with your doctor if you have been exposed to either of the following:

• Ethambutol

• Methanol

In addition to MS, the risk factors for developing optic neuritis, include:

• Age: Adults 20 to 40 years are the age group most often affected.

• Sex: Women are more likely to have it than men, research shows.

• Race: Optic neuritis is seen most often in Caucasian/white people.

• Genetic mutations: Some genetic mutations could increase the chance of optic neuritis or multiple sclerosis.

The risk of developing MS after optic neuritis without an MS diagnosis is also significant, Dr. Galetta says. “The risk of MS is anywhere from 25% to 80% once you have had optic neuritis. If your brain MRI is abnormal, the risk of MS approaches 80%. If normal at baseline, the risk is close to 25%.” For comparison, the risk of developing MS in the general population is just .5%.

Bottom line: Recognizing the symptoms of optic neuritis, as well as getting prompt diagnosis and treatment from an eye care professional and neurologist, can make a world of difference for not just your vision, but also your overall health. This way, if you do receive an MS diagnosis, you can start treatment ASAP and slow the progression of the disease.

So how is optic neuritis diagnosed? Your ophthalmologist will typically do a few tests and exams to determine if your symptoms indicate optic neuritis, according to Dr. Krauss:

• Visual acuity test (to test how well you see)

• Visual field test (to test your peripheral vision, which should still be fine)

• Color sensitivity test (to test how well you can see colors)

• Fundus exam (to see the back of the eye where the optic nerve is)

• Optical coherence tomography test (this will give your doctor a high-resolution image of the optic nerve and its related structure)

If your doctor diagnoses you with suspected optic neuritis, generally within a day or two of the eye exam, you’ll have an MRI of your brain and eye orbits. “In doing the MRI, we’re looking for inflammation within the optic nerve behind the eye. And we’re also looking for other types of inflammation in the brain itself,” Dr. Krauss says.

Once you get a diagnosis of optic neuritis (and maybe MS), you’ll start a treatment plan with your doctor—sometimes a short course of intravenous steroids, says Dr. Galetta. “Steroids do not improve the final visual outcome, but they may accelerate the recovery of vision by several weeks compared to simple observation.” However, the decision to use steroids does depend on the doctor, and some doctors just observe while treating the MS.

The typical long-term outcome of optic neuritis is reasonably good. Most patients achieve a visual acuity of 20/40 or better, according to the Journal of Neuro-Ophthalmology. That means, you may or may not need glasses or contacts. In most cases, though, there’s a degree of lasting damage. “Most patients experience some residual visual impairment in the affected eye and many will report a reduced visual quality of life compared to controls,” Dr. Galetta says.

Optic neuritis tends to be a one-time event. However, there are instances in which it returns, what’s known as “recurrent optic neuritis.” It can come back in the same eye, or in the other eye about 15 to 20% of the time, according to MS Focus Magazine. Relapses are usually treated the same as the initial flare-up, sometimes with steroids.

If optic neuritis goes untreated, it can worsen, so it’s best to seek medical attention at the onset of symptoms. If you’re experiencing optic neuritis symptoms but don’t have an MS diagnosis, you should call your eye doctor right away, says Rosemarie E. Walch, D.O., a neurologist at MIND (Michigan Institute for Neurological Disorders), a National Multiple Sclerosis Society-recognized Center for Comprehensive MS Care, in Roseville, MI. If you have MS, see your neurologist.

Eye doctors with an M.D. degree—called ophthalmologists—will refer you for a neurology evaluation if they suspect MS, particularly if you don’t yet have a neurologist, according to Dr. Walch. If you already have an MS diagnosis and see a neurologist, however, “Any new neurological symptoms, including optic neuritis, lasting longer than 24 hours, warrants a phone call to your neurologist,” she advises.

Specialized ophthalmologists, like Dr. Krauss, can help you with an optic neuritis diagnosis. He says O.D. degree eye doctors (optometrists) can be excellent help if you can’t access an ophthalmologist or neurologist immediately but have concerns about new-onset eye symptoms.

Bottom line: Recognizing the symptoms of optic neuritis, as well as getting prompt diagnosis and treatment from an eyecare professional and neurologist, can make a world of a difference for not just your vision, but also your overall health. This way, if you do receive an MS diagnosis, you can start treatment ASAP and slow the progression of disease.