Optic neuritis is an eye condition that can sometimes be linked to multiple sclerosis (MS), a disease that affects the brain and spinal cord. However, optic neuritis can also happen in other conditions, such as neuromyelitis optica spectrum disorder (NMOSD) or myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD).

This article focuses on optic neuritis and how it relates to NMOSD. Because NMOSD can look a lot like MS, especially in the early stages, doctors used to think it was a form of MS. Although both conditions can cause optic neuritis, they have key differences. Continue reading to learn about NMOSD and optic neuritis.

What Is Optic Neuritis?

Optic neuritis happens when the optic nerve, which carries signals from your eyes to your brain, gets inflamed. This inflammation damages a protective layer called the myelin sheath, which surrounds the optic nerve. As a result, the nerve can’t send visual signals as well, leading to vision problems or even temporary vision loss.

Common symptoms of optic neuritis include:

• Eye pain, usually a dull ache that gets worse when you move your eye
• Reduced visual acuity (blurry or less sharp vision)
• Gaps in your visual field, such as blind spots in the center or sides of your view
• Loss of color vision, in which colors don’t look as bright or clear as usual

Optic Neuritis Is Common in Neuromyelitis Optica

In the past, neuromyelitis optica spectrum disorder was called Devic’s disease. Today, the condition may also be referred to as just neuromyelitis optica (NMO).

NMOSD is a rare type of autoimmune disease that affects the optic nerve, spinal cord, or certain parts of the brain. The spinal cord is part of your central nervous system (CNS), which controls how your brain communicates with your body.

Problems with the immune system cause NMOSD. Specifically, immune cells make autoantibodies (harmful antibodies) that attack parts of the nerves. Most people with NMOSD have autoantibodies that target aquaporin-4 (AQP4), a protein on nerve cells that regulates water.

Some people with NMOSD symptoms don’t have AQP4 antibodies and are called seronegative. Others who have symptoms are found to have antibodies against a different protein called myelin oligodendrocyte glycoprotein (MOG), leading to MOGAD, which is a separate disease.

When AQP4 antibodies attack the optic nerve, it causes optic neuritis. Optic neuritis is the most common symptom of NMOSD in people who develop this condition before age 40.

Doctors sometimes refer to NMOSD-related optic neuritis as atypical optic neuritis because it behaves differently from the optic neuritis seen in other conditions. In NMOSD, optic neuritis is often more severe and affects both eyes, instead of just one like in MS. Early treatment is crucial to help protect vision.

Pain with eye movement is common in NMOSD, but not everyone experiences it, depending on where the optic nerve is attacked. Atypical optic neuritis is more likely to cause more serious vision problems than optic neuritis related to other conditions.

NMOSD is an autoimmune condition that can cause optic neuritis, along with symptoms beyond the eyes and vision.

Neuromyelitis Optica Symptoms May Extend Beyond the Eyes

NMOSD doesn’t just affect the eyes. This condition can also affect the spinal cord and brain, leading to a wide range of symptoms in other parts of the body.

Transverse Myelitis

When NMOSD causes inflammation in the spinal cord, it’s called transverse myelitis. This swelling can block or slow down the nerve signals between your brain and body. The result is a mix of symptoms that depend on where the inflammation happens. Symptoms of transverse myelitis may include:

• Muscle weakness
• Paralysis (inability to move part of the body)
• Pain in the back, arms, or legs
• Problems controlling the bladder or bowels
• Sexual dysfunction (trouble with arousal or sensation)

Brain Symptoms

Although it’s less common, NMOSD can also affect the brain. If NMOSD affects the brainstem (the lowest part of the brain that connects to the spinal cord) or hypothalamus (a small area that controls functions like body temperature, hunger, and sleep), it can cause symptoms such as:

• Hiccups
• Itching
• Double vision
• Dizziness
• Facial paralysis or pain
• Balance problems
• Daytime sleepiness

Other Conditions Can Cause Optic Neuritis

NMOSD isn’t the only cause of optic neuritis. Other medical conditions, especially those involving the immune system or infections, can also lead to inflammation of the optic nerve. Here are some of the main ones.

Multiple Sclerosis

Like NMOSD, MS is an autoimmune disease. MS is known as a demyelinating disease — the immune system attacks and damages the myelin sheath around the nerve cells. When MS attacks the optic nerve, it can cause optic neuritis.

Optic neuritis may be caused by multiple sclerosis, lupus, infections, and certain medications, as well as by NMOSD.

MS-related optic neuritis is often called typical optic neuritis because it typically affects just one eye and often comes with eye pain. For some people, optic neuritis is the first sign of MS. Researchers have found that about half of people who have typical optic neuritis will be diagnosed with MS within 15 years.

Other Autoimmune Diseases

Conditions such as systemic lupus erythematosus (SLE, the most common type of lupus) and sarcoidosis (a rare disease that mostly affects the lungs and lymph nodes) are also associated with optic neuritis. These inflammatory autoimmune diseases may cause swelling in or around the optic nerve. For example, SLE can cause retinal vasculitis, which is inflammation in the blood vessels at the back of the eye and can lead to vision loss.

Infections

Certain viral and bacterial infections can affect the brain and cause optic neuritis. Viral illnesses such as measles, chickenpox, and herpes have been linked to optic neuritis, as have bacterial infections including syphilis, Lyme disease, and tuberculosis. Fungal and parasitic infections have also been associated with optic neuritis.

Medications and Toxins

Researchers believe that some medications and toxic substances may directly damage the optic nerve, which is called optic neuropathy. Examples of drugs and substances linked to optic neuropathy include:

• Certain antibiotics that are used to treat tuberculosis and malaria
• Some heart rhythm medications
• Chemotherapy drugs (cancer treatments)
• Tobacco products
• Alcohol

Other Health Conditions

Some health issues can cause optic nerve damage that looks like optic neuritis but isn’t caused by inflammation. This is often better described as optic neuropathy. For example, vitamin B12 deficiency (low vitamin B12 levels) can cause optic nerve damage over time. Type 2 diabetes can cause long-term damage to the optic nerve from high blood sugar. Tumors, blood clots, or any other condition that cuts off blood flow or puts pressure on the optic nerve can also cause optic neuropathy.

Diagnosing Optic Neuritis Means Finding the Underlying Cause

Because optic neuritis can be caused by different conditions, diagnosis requires figuring out what’s behind the symptoms. Doctors use a process called differential diagnosis, which involves ruling out several possible causes one by one. NMOSD is one of the conditions healthcare providers often consider in the differential diagnosis.

Diagnostic tests for optic neuritis may include:

• An eye exam to check for vision loss and other vision problems
• Physical and neurological exams to look for signs and symptoms of other nervous system problems
• Blood tests to look for antibodies linked to autoimmune diseases like NMOSD
• Magnetic resonance imaging (MRI) to reveal any lesions (areas of damage) on the brain, spinal cord, or optic nerve
• Lumbar puncture (spinal tap) to test cerebrospinal fluid (CSF) for signs of infection or inflammation

During diagnosis of optic neuritis, your healthcare team will identify the cause by ruling out other health conditions.

In the early stages of NMOSD, optic neuritis signs and symptoms sometimes look like those of MS. Testing for NMOSD-specific antibodies, especially the AQP4 antibody, can help doctors tell these conditions apart. People with NMOSD-related optic neuritis usually test positive for AQP4, whereas most people with MS do not.

Treatment for Neuromyelitis Optica and Optic Neuritis Involves Reducing Inflammation

Initial treatment for optic neuritis usually involves reducing inflammation. Doctors generally start with high-dose corticosteroids (steroids), a type of anti-inflammatory medication, to help protect the optic nerve and improve vision.

However, some people with NMOSD-related optic neuritis don’t respond well to steroids alone. In those cases, doctors may use plasma exchange (also called plasmapheresis). This treatment works by removing harmful antibodies and inflammatory substances from the blood to help stop the immune system from attacking the optic nerve.

After the acute (sudden) symptoms are treated, the next goal is to prevent optic neuritis from relapsing (coming back). The right long-term treatment depends on the underlying cause. For people with NMOSD, immunosuppressive treatments can help calm the immune system and reduce the risk of relapses. These medications include:

• Azathioprine (Azasan, Imuran)
• Eculizumab (Soliris)
• Inebilizumab-cdon (Uplizna)
• Mycophenolate mofetil (CellCept)
• Ravulizumab-cwvz (Ultomiris)
• Rituximab (Rituxan)
• Satralizumab-mwge (Enspryng)

If you’ve been diagnosed with optic neuritis, you and your healthcare team will work together to find the best treatment plan for you.

Talk With Others Who Understand

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Have you been diagnosed with optic neuritis? What symptoms did you have? Did your healthcare team diagnose the underlying cause of your optic neuritis? Share your experience in the comments below, or start a conversation by posting on your Activities page.