According to ADAM Medical Encyclopedia, optic neuritis is "inflammation of the optic nerve; it may cause sudden, reduced vision in the affected eye." Though the exact cause is unknown, sudden swelling of the optic nerve – including damage to the myelin sheath surrounding the nerve – can result in disturbances in vision.
As described by MS patient Lisa Emrich, "I woke up on a Tuesday morning with globs of Vaseline smeared over my right eye. Well, not literally, but that's what it looked like as I peered through my glasses and started to cry."
If optic neuritis is suspected, a patient should see a doctor immediately. This could be indicative of far more challenging conditions. Doctors may conduct a variety of tests, including a color vision test, an MRI of the brain (and specifically of the optic nerve), visual activity testing, visual field testing and an examination of the optic disc using indirect ophthalmoscopy.
Optic neuritis is common in about half of MS patients. Patients may experience double vision or blurred vision, though often only in one eye. As MS progresses, vision loss can increase, though blindness is rare.
Without treatment, vision can return within two to three weeks. Corticosteroids can also be given through an IV or taken by mouth. This can help speed up the recovery process, though higher doses should be taken with caution as there could be serious complications. It is also paramount that further tests be conducted to indicate the cause of the optic neuritis.
According to ADAM Medical Encyclopedia, "people who have optic neuritis without a disease (such as MS) have a good chance of recovery. However, optic neuritis caused by MS has a poorer outlook. " Despite this, "vision in the affected eye may still return to normal."