What is optic neuritis?

Optic neuritis is an acute demyelinating inflammation of the optic nerve. The optic nerve is responsible for our vision by transferring the image from the eye to our brain. It can be compared to a cable that includes many, very thin, “electrical wires”, about 1,200,000 of them, called nerve fibers. Each fiber transfers part of the visual information to the brain.

In optic neuritis, the nerve tissue gets inflamed and the nerve fibers stop working properly. If a lot of the fibers are affected, then vision is decreased significantly, but if optic neuritis is mild, then our vision remains almost normal.

Normal optic nerve	Optic neuritis	Optic neuritis

Typical clinical image of the disease includes sudden decrease in vision and visual fields, which is followed, in most cases, by an automatic improvement.

What causes optic neuritis?

Many diseases and conditions can cause optic neuritis, but in many cases the cause of optic neuritis remains unknown. The causes of optic neuritis might be:

Demyelination
Infection (syphilis, cat-scratch disease, spreading of the infection from the orbit of the eye, the nearby paranasal sinuses or the meninges)
After a viral infection (measles, mumps, rubella, chicken pox etc.)
Systemic autoimmune diseases
However, when we talk about optic neuritis, we mean partial or total loss of vision caused by demyelination, during which the nerve fibers lose their insulating myelin sheath that surrounds them, which results in problematic conduct of nerve impulses. The most frequent form is the one related to multiple sclerosis (MS).
It has been calculated that patients who develop optic neuritis, but everything appears normal in a brain MRI, have 16% chances to develop MS within 5 years. Furthermore, of those that have a first episode of optic neuritis, 50% of them show lesions in the MRI and it is them with higher risk of developing MS in 5-10 years.

What are the symptoms of optic neuritis?

Optic neuritis usually appears suddenly. The patient who presents symptoms of neuritis usually:

is 15-45 years old
is a woman
has one-sided decrease in vision that worsens for 5-8 days
complains about pain in or around the eye, that worsens with eye movements
has blurry vision in one or both eyes, especially after physical exercise or a warm bath
starts seeing improvement in his or her vision after 3-4 weeks and this continues for a period of 6 months when maximum restoration is reached
shows other symptoms like sudden disturbance in color perception by the afflicted eye (acquired color blindness) and distortions in the visual fields.

How can optic neuritis be diagnosed?

For the doctor to diagnose optic neuritis it is important to give him a detailed account of the symptoms and he will move on to a full ophthalmological examination. By examining the fundus, the doctor seeks for an edema of the optic nerve at the posterior segment of the eye.

If optic neuritis does not affect the optic nerve near the eye, then the nerve might appear normal. Since optic neuritis may be confused with a lot of other causes of diminished vision, a precise diagnosis is necessary.

Other tests that the ophthalmologist can use include chromatic perception, peripheral vision (visual field) tests, as well as the pupil's reaction to light. Visual and somatosensory evoked potential, ultrasounds, and brain/cervical spine MRI, electroencephalography (EEG) or lumbar puncture (shows increase in IgG immunoglobins) may also be suggested by the ophthalmologist. If the cause is found and treated, it is possible to prevent further damage.

How is optic neuritis treated?

Fortunately, most patients return to normal vision without any treatment. Even though some people may experience visual distortions from neuritis, these are usually very mild.

Research has shown that steroids (cortisone) taken orally do not help with optic neuritis. In some people with significant loss of vision, however, treatment with cortisone injected intravenously might prove beneficial.

Remember:Your ophthalmologist is the best source for responsible answers on issues related to your eyes and their health. Under no circumstances is information taken from our website intended to replace him. Seek your doctor for complete information.