What is Optic Neuritis?
The eye is connected to the brain by a bundle of nerve fibers called the optic nerve. Inflammation of the optic nerve is referred to as optic neuritis, and it is manifested as eye pain and temporary loss of vision.
Optic neuritis (ON) may result from a viral infection involving the area around the eyes and sinuses, but in many cases it is associated with multiple sclerosis, a chronic autoimmune condition affecting the covering of the nerves. More women than men are affected, usually during early to middle adulthood, and caucasians seem to be more predisposed to it than any other race.
Optic neuritis eventually leads to a loss of color vision and a decrease in or complete loss of vision. This can occur within days and may be worsened by heat or exercise. Since ON has been associated with a high incidence of multiple sclerosis (MS), the likelihood of developing the latter is great, so treatment for ON may include prevention of MS.
Treatment of Optic Neuritis
The treatment of ON is geared toward pain relief, decreasing the inflammation of the nerve, recovery of vision and preventing blindness. This includes different modalities, including:
- Intravenous (IV) steroids – corticosteroids like methylprednisolone, usually administered in high doses, initially while in the hospital
- Oral steroids – like prednisone, used for tapering the doses of steroids while taken at home
- Plasma exchange or plasmapheresis, which involves the removal, treatment and return of blood components from the patient’s circulation
- Use of immunomodulators, like interferon, to decrease immune reactions
Steroids and Optic Neuritis
The use of steroids for optic neuritis remains controversial, because of its lack of long-term protection against blindness and multiple sclerosis. Although steroids have an anti-inflammatory and immunosuppressant effect, they do not completely prevent the development of MS, but they may delay its course.
Steroids have been more effective in preventing loss of vision in patients who have isolated ON, rather than those cases which are related to MS.
Hospitalization for IV administration of steroids in high doses for a duration of 3 days is recommended, to avoid the risks of adverse events related to the therapy. Many doctors follow this up with an oral tapering dose of steroids, to prevent adrenocortical insufficiency, a complication of sudden withdrawal of steroids. Some doctors, though, do not believe this is necessary in a short course of therapy.
The anti-inflammatory and immunosuppressant effects of steroids may produce side effects, such as susceptibility to infection. Other side effects include increases in blood pressure and blood sugar levels, mood swings and weight gain. Long term use can lead to osteoporosis or thinning and weakening of bones and the formation of cataracts.
Steroids may help in the recovery of vision loss in the acute phase of the disease, but they do not guarantee long term protection. In some, recovery of vision within a couple of weeks occurs, even without treatment, although residual decrease in color vision and sensitivity to brightness and contrast may persist.
Steroids may improve vision during the initial episode, but relapses or recurrent attacks of ON can occur. Some do not respond at all, though, and may need plasmapheresis or immunomodulators to help them recover their vision.
Finally, steroids and interferons may delay the development of multiple sclerosis, although a complete cure is not predicted.
Mayo Clinic. “Optic Neuritis,”https://www.mayoclinic.com/health/optic-neuritis/DS00882
Medscape. “Optic Neuritis, Adult: Treatment & Medication,” https://emedicine.medscape.com/article/1217083-treatment