Optic neuritis is a condition that affects the eye and your vision. It occurs when your optic nerve is inflamed and swollen.

The optic nerve sends messages from your eyes to your brain so that you can interpret visual images. When the optic nerve is irritated and inflamed, it doesn't carry messages to the brain as well. You can't see clearly.

Optic neuritis can affect your vision and cause pain. When the nerve fibers become inflamed, the optic nerve can also start to swell. This swelling typically affects one eye. But it can affect both at the same time.

Optic neuritis can affect both adults and children of all ages. It's most commonly seen in white females between the ages of 20 and 40.

Loss of vision in optic neuritis commonly reaches its maximum effect within a few days and starts improving within 4 to 12 weeks.

The cause of optic neuritis isn't always clear. It may be caused by a viral infection that triggers the immune system to attack the optic nerve. It's also a common condition among those who have multiple sclerosis (MS), which is a progressive autoimmune nervous system disorder. About 50% of people who have MS will develop optic neuritis. It's often the first sign of MS. Another inflammatory condition called neuromyelitis optica can also attack the optic nerve and the spinal cord. The symptoms are similar to MS, but it's a different disorder.

You are at increased risk for optic neuritis if you:

• Have a history of MS or neuromyelitis optica.
• Live in higher altitudes.

The following visual problems are common with optic neuritis:

• Diminished vision (usually the main symptom)
• Trouble distinguishing colors, or noticing that colors aren't as vibrant as usual
• Vision that appears blurry—particularly if it occurs after your body temperature has risen—after you've just taken a hot shower or finished a workout, for instance
• Inability to see out of one eye
• Abnormal reaction of the pupil when exposed to bright light
• Pain in the eye, especially when you move it

The symptoms of optic neuritis can vary widely in severity. More extensive optic nerve inflammation leads to more noticeable symptoms.

Just because you have severe symptoms doesn't necessarily mean that optic neuritis will never go away. Plus, not everyone who has optic neuritis has problems with their vision. It's possible for the optic nerve to be inflamed without affecting vision. A careful, medical evaluation of the eye can diagnose optic neuritis even if you don't have symptoms.

Your doctor can diagnose optic neuritis with these tests:

• Thorough medical exam
• Evaluation of your eyes' response to direct bright light
• Testing of visual acuity using the letter chart to see how well you can see
• MRI scan of the brain and eyes

• Testing of the ability to differentiate color
• Exam of the back of the eye, known as the fundus
• Visual brain wave recording
• Visual field testing
• Spinal tap (lumbar puncture), less commonly needed
• Blood tests to look for antibodies or proteins that attack the optic nerve

More testing may help to determine the underlying cause of the optic neuritis. But identifying a specific cause isn't always possible.

In some cases, you may not need any treatment for optic neuritis. After a few weeks, it may go away on its own and your vision will return to normal. This is more likely if you don't have another health condition that has triggered the optic neuritis.

Sometimes your doctor may recommend a brief course of steroids, usually injected into your vein. These may help your vision improve more quickly and minimize inflammation and swelling.

You may also need treatment for another health condition if it's considered the source of your optic neuritis. If your doctor thinks MS or neuromyelitis optica is causing the condition, they will discuss other diagnostic tests and long-term treatment options with you.

Taking corticosteroids on a long-term basis can lead to side effects, such as high blood sugar, weight gain, and bone problems, which affect your whole body. Overall, corticosteroids may not lead to a better outcome than letting the condition run its course. But in people with certain brain changes seen on MRI, I.V. (intravenous) steroids may help prevent future episodes of optic neuritis.

If you have eye pain or any trouble with your vision, see your doctor right away for an eye exam. If you've already been diagnosed with optic neuritis, contact your doctor if your symptoms change, worsen, or don't get any better.

• Optic neuritis is a condition that affects the eye and your vision. It occurs when your optic nerve is inflamed and swollen.
• It can affect your vision and cause pain. When the nerve fibers become inflamed, the optic nerve can also start to swell. One eye is more commonly affected; however, it can occur in both eyes as well.
• It may be caused by an infection. But it is a common condition among people who have multiple sclerosis (MS).
• See your doctor if you think you may have optic neuritis. You may have another health condition that's causing it.
• A complete medical exam may help your doctor find other health conditions that can be treated.

Tips to help you get the most from a visit to your doctor:

• Know the reason for your visit and what you want to happen.
• Before your visit, write down questions you want answered.
• Bring someone with you to help you ask questions and remember what your doctor tells you.
• At the visit, write down the name of a new diagnosis and any new medicines, treatments, or tests. Also write down any new instructions your doctor gives you.
• Know why a new medicine or treatment is prescribed and how it will help you. Also know what the side effects are and when they should be reported.
• Ask if your condition can be treated in other ways.
• Know why a test or procedure is advised and what the results could mean.
• Know what to expect if you don't take the medicine or have the test or procedure.
• If you have a follow-up appointment, write down the date, time, and purpose for that visit.
• Know how you can contact your doctor if you have questions.