Optic Neuritis: Symptoms, Causes, Treatment and Recovery

Optic neuritis is inflammation of the optic nerve, which carries visual messages from each eye to the brain. Vision in one eye often dims or blurs over hours to days, with pain around the eye that gets worse when the eye moves and colors that look faded. It is often the first symptom of multiple sclerosis (MS), and infections and other immune conditions can cause it too. Most people regain near-normal vision over weeks to months. Sudden vision loss, even if it comes back, is a 911 call, because sudden vision changes are a stroke warning sign; if you can't tell whether it was sudden, treat it as sudden. Vision that has faded over hours or days, with pain when you move the eye, needs a same-day eye exam, or an emergency room when we're closed.

Key takeaways

With optic neuritis, an inflamed optic nerve, vision in one eye often dims over hours to days, and pain around the eye worsens when it moves.
Optic neuritis is often the first symptom of multiple sclerosis (MS), and about half of people develop MS within 15 years of a first episode.
Vision usually returns to near normal over weeks to months, treated or not, and nearly 90% of people get there by 6 months.
Sudden vision loss, even if it comes back, means calling 911, and vision fading over hours or days needs a same-day exam, or an emergency room when we're closed.

What is optic neuritis?

Optic neuritis is an inflammatory condition of the optic nerve that can affect vision in one or both eyes. Each eye has its own optic nerve, a bundle of more than 1 million nerve fibers that connects the retina (the light-sensitive layer at the back of the eye) to the brain, and damage to that nerve can cause vision loss.

It most often affects young adults, typically between ages 20 and 50, and women get it more often than men.

What are the symptoms of optic neuritis?

The usual pattern is vision loss in one eye that builds over hours to days, together with pain around the eye. Symptoms can include:

Blurred, dim or darkened vision in one eye
Pain around the eye that gets worse when you move it, which comes from inflammation of the sheath around the nerve
Colors that look faded or washed out, and weaker contrast vision
Vision loss that gets worse after exercise or when your body temperature rises, known as Uhthoff phenomenon

The pain with eye movement usually eases within days to weeks.

Is optic neuritis an emergency?

It needs an eye exam the same day, or an emergency room when we're closed, and some vision changes need 911. Sudden changes in vision are one of the stroke warning signs, and the cause can't be sorted out at home, so let the speed of the change, and what comes with it, decide what you do:

Call 911 if vision in one or both eyes suddenly dims or goes dark, even if it comes back; if you suddenly see double, or see double with eye pain or a severe headache; or if any change in vision comes with face drooping, arm weakness, trouble speaking or loss of balance. If you can't tell whether the change was sudden, treat it as sudden.
Call us immediately at 310-828-2010 if vision in one or both eyes has dimmed or blurred over hours or days, especially with pain when you move the eye. We hold same-day slots for urgent eye problems during office hours, Monday 10 to 5 and Tuesday through Friday 8 to 5. When we're closed, go to an emergency room.
Call us immediately, or go to an emergency room when we're closed, for a dark shadow or curtain over part of your vision, a lot of new floaters or new flashes of light. These are warning signs of a retinal detachment, which is a medical emergency.

What causes optic neuritis?

Optic neuritis is often the first sign of demyelination, which is damage to myelin, the protective sheath that coats nerve fibers. The causes include:

Multiple sclerosis (MS), in which the immune system attacks myelin in the brain and spinal cord
Neuromyelitis optica spectrum disorder (NMOSD), an autoimmune condition of the optic nerve and spinal cord that is distinct from MS, and MOG antibody-associated disease (MOGAD), another immune condition
Infections, including shingles (herpes zoster), Epstein-Barr virus, measles, syphilis and Lyme disease
Lupus and sarcoidosis, as part of the inflammation they cause throughout the body

Sometimes no cause is found.

Does optic neuritis mean I have MS?

Not always. About half of people develop MS within 15 years of a first episode of optic neuritis.

An MRI helps estimate your own risk. MRI of the brain and orbits (the eye sockets) with contrast dye is the standard imaging test for optic neuritis, and lesions in the brain's white matter raise the chance of MS.

MS usually starts between ages 20 and 40 and is more common in women. Eye and vision problems are common in MS but rarely lead to permanent blindness, and disease-modifying therapies can reduce how often attacks happen.

How is optic neuritis diagnosed and treated?

Diagnosis starts with an eye exam. When only one eye is affected, a pupil test often shows that the affected eye's pupil responds less to light, a sign called a relative afferent pupillary defect, which eye doctors find with the swinging flashlight test.

Visual field testing, OCT (optical coherence tomography) scans and an MRI fill in the picture. OCT can show thinning of the nerve fiber layer, a sign of optic nerve damage. Doctors look harder for a different cause when vision is lost in both eyes, the loss is profound or there was no eye pain before it, especially when other nerve symptoms don't fit the usual pattern.

Treatment depends on the cause. In the Optic Neuritis Treatment Trial, vision improved faster with intravenous methylprednisolone (steroids given through a vein). Steroids did not change long-term vision, and oral prednisone alone led to more repeat attacks.

NMOSD is treated differently. Corticosteroids calm the immune system during an attack, plasma exchange filters harmful antibodies out of the blood, and other medicines help prevent new episodes.

How long does optic neuritis last?

Vision usually returns to near-normal over weeks to months, whether or not it is treated, and nearly 90% of people reach near-normal vision by 6 months.

Optic neuritis can come back. Repeat episodes raise the possibility of a wider condition such as MS, NMOSD or MOGAD, so tell your eye doctor about any earlier episode.

How we check for optic neuritis at Cohenmehr Optometry

If it isn't a 911 call, phone 310-828-2010 and tell us what changed, in which eye and when. A person answers and triages the call, and urgent cases are worked into the same day; when we're closed, go to an emergency room.

The urgent work-up with our eye doctors in Los Angeles uses the slit lamp, pressure checks, dilation and imaging as your symptoms demand, including OCT scans of the optic nerve and visual field testing when needed. The scans also give us a baseline to compare at later visits, the same way our comprehensive eye exams use imaging.

When the exam points to optic neuritis, the next steps are an MRI and specialist care. We coordinate the urgent referral to an ophthalmologist, and your records and images go the same day.

Questions patients ask

Can optic neuritis cause color blindness?

It can reduce color vision in the affected eye, which is different from the color blindness most people are born with. The National Eye Institute notes that color vision deficiency can come from an injury to the optic nerve, and it lists multiple sclerosis among the health problems that raise the risk. To test color vision, an eye doctor shows you a circle of colored dots with a number or shape hidden inside.

Can optic neuritis cause a blind spot in your vision?

Yes. Almost any pattern of vision loss can appear, but a blind spot in the center of vision, called a central scotoma, is the most common one on automated visual field testing. It can look like a blurry or gray patch right where you're looking. A visual field test maps the blind spot so changes can be tracked as the nerve heals.

Can a dilated eye exam detect optic neuritis?

It can show signs of it, but a normal-looking nerve doesn't rule it out. During an attack, swelling of the optic disc, where the nerve meets the back of the eye, shows up in about one third of people; in the others the nerve can look normal. That's why the diagnosis also leans on the pupil test, color and side vision testing, OCT scans and an MRI.

Does optic neuritis cause flashes of light?

It can. Some people see brief flashes of light or flickering, called phosphenes, especially when they move their eyes or are in dim light. New flashes are also a warning sign of a retinal detachment, a medical emergency, so don't assume they come from the nerve. Call us right away for a same-day exam, or go to an emergency room when we're closed.

Sources

Written by

Dr. Kevin Cohenmehr, OD

Medical eye care: glaucoma, diabetic eye exams, macular degeneration and eye infections, plus vision therapy for children. A graduate of UCLA and SUNY College of Optometry.

About Dr. Kevin →

Optic Neuritis: Symptoms, Causes and What Recovery Looks Like