Optic Neuritis: Symptoms, Causes & Treatment

What is an Optic Neuritis?

Optic neuritis (ON) occurs when the optic nerve becomes inflamed. The optic nerve is a bundle of fibers connecting your eye to the brain, allowing you to see.

When the optic nerve is inflamed, it can lead to vision problems such as color blindness and blurry vision. It may also cause one or both of your eyes to swell.

Anyone can get ON, but it’s more common among those with multiple sclerosis (MS). Although some symptoms of ON may seem scary, most people recover without treatment. 

What Causes Optic Neuritis?

In most cases, the exact cause of ON isn’t fully understood. However, several factors can lead to inflammation.

For example, your own immune system can attack itself through an autoimmune disease, like MS. This causes your body to mistakenly attack the protective coating of the optic nerve.

It can also be caused by viral infections such as measles, mumps, or herpes. These conditions can trigger an immune response, which can damage the optic nerve. Meanwhile, bacterial infections such as Lyme disease, syphilis, and tuberculosis have also been associated with optic neuritis.

Who is at Risk for Optic Neuritis?

Women are three times more likely than men to get ON. Caucasian people are also at a higher risk compared to others. 

Other risks include:

• Aged between 20 to 40 years
• Have multiple sclerosis 
• Live in a high-altitude area
• Have certain genetic mutations

What Are the Symptoms of Optic Neurotits?

Optic neuritis often affects one eye. The most common symptoms include:

• Sudden vision loss. This can range from mild blurriness to profound vision loss, typically developing over hours or a few days.
• Eye pain. You might experience a dull ache behind the affected eye that worsens when you move your eyes.
• Loss of color vision. Colors may appear faded, washed out, or less vibrant than usual.
• Flashing lights. You may notice flickers of light, especially with eye movement.

In addition to the side effects mentioned above, you may experience long-term side effects like reduced visual acuity or color blindness.

In some cases, you may experience recurrent ON attacks due to diseases like neuromyelitis optic devicta spectrum disorder (NMO-SD) and myelin oligodendrocyte glycoprotein (MOG) antibody disease.

If left untreated, this may lead to the progression of MS, complete vision loss, and nerve problems in other parts of the body.

How is ON Diagnosed?

If you think you have optic neuritis, see a doctor immediately for a comprehensive evaluation. Getting an accurate diagnosis for ON early greatly improves the outcome of treatment.

A neurologist or ophthalmologist will assess your symptoms and medical history through a comprehensive eye exam. This includes specific tests for diagnosing optic nerve damage.

Here are some tests commonly used to diagnose ON:

• Eye exam. Your doctor will carefully examine your eyes, including checking your visual acuity, color vision, and the way your pupils react to light.
• Visual field test. This test maps your field of vision to detect blind spots or other changes that are common in optic neuritis.
• Ophthalmoscopy. This test involves looking directly at the back of your eye to assess the optic nerve and the blood vessels around it.
• MRI scans: MRI creates detailed images of the optic nerve and brain, helping to detect inflammation or signs of conditions like multiple sclerosis.
• Optical coherence tomography (OCT): Provides high-resolution pictures of your retina and optic nerve to measure the thickness of delicate nerve layers.
• Visual evoked potentials (VEP): Tests the speed of electrical signals traveling from the eye to the brain and can reveal any delays caused by optic nerve damage.

Treatment Options for Optic Neuritis

In most cases, optic neuritis is short-lived and resolves by itself without treatment after 4 to 12 weeks. Your vision will typically improve as the inflammation subsides.

However, treatment is often required for people who experience severe or chronic ON. Treatment typically depends on the cause of the inflammation. 

Here are some treatment options for ON:

• Steroids. Corticosteroids are the most common treatment for reducing inflammation. However, they may not necessarily improve the final degree of vision you regain.
• Plasma exchange therapy (PLEX). Removes harmful antibodies from your blood to reduce inflammation. Used for conditions like NMO-SD or when steroids don’t work.
• Intravenous immunoglobulin (IVIG). Similar to plasma exchange, IVIG helps modulate immune responses and can be considered for treating severe cases of optic neuritis.
• Vision rehabilitation. Can help maximize your remaining vision, provide vision aids, and recommend adaptive strategies to manage vision.
• Managing underlying conditions. Managing autoimmune disorders like MS can help manage ON and prevent future episodes.
• Surgery. In rare cases, if a tumor or other growth is compressing the optic nerve, surgery may be necessary to relieve the pressure.

Some studies suggest that complementary therapies, such as neuroprotective strategies and gene therapy, can stimulate the regeneration of optic nerve cells. However, more research is needed.

What is The Outlook of Optic Neuritis?

Although the condition may resolve itself after a few weeks, some symptoms, such as reduced vision, may persist. Sometimes ON may occur without MS or NMO, resulting in a disorder known as chronic relapsing inflammatory optic neuropathy (CRION).

CRION is associated with more intense pain and discomfort than optic neuritis occurring alongside MS. There is also a significant risk of blindness with CRION.

Fortunately, CRION can be treated with intravenous (IV) steroids. Oral steroids and other medications may be taken to avoid recurrence.