Optic neuritis (also called retrobulbar retinitis) is an inflammation of the optic nerve the “cable” that transmits visual information from the eye to the brain. (Optic = eye; retrobulbar = behind the eye; neuritis = nerve inflammation.) The optic nerve plays such a key role in vision that anything that happens to it affects eyesight. When inflammation is mild vision can be almost normal but severe inflammation can cause loss of vision.
Optic neuritis can occur in one or both eyes. If in both it is typically more severe in one of them. Many people have an attack of optic neuritis only once and the reason for the attack remains a mystery. Vision in the affected eye usually recovers almost completely though there may be a slight reduction in visual acuity or color vision.
Early symptoms can include blurred vision that grows dimmer over a few hours or days. Colors may look washed out. Your eyes may ache or you may have a dull pain or uncomfortable pulling feeling whenever you move the eye especially on looking up. All the symptoms are made worse by exercise or a hot bath. Very rarely vision may go dark for a week or so.
WHAT CAUSES THE INFLAMMATION?
Many conditions can cause inflammation of the optic nerve. Some are temporary some are recurrent and some are more permanent. Several medical and neurological diseases can result in an inflamed optic nerve (such as Multiple Sclerosis). Other causes are bacterial infections (such as Syphilis Lyme disease and Cat-Scratch-Fever). A viral illness such as measles mumps or even a cold can cause optic neuritis.
Your visual acuity will be measured with an eye chart and you will have a refraction to determine whether any decreased vision can be corrected with lenses. The reaction of your pupils to light will be checked with a flashlight. Your pupils will be dilated (enlarged) with eyedrops so an ophthalmoscope can be used to examine the retina and optic nerve inside the eye and a visual field test may be done to determine the pattern of any lost vision. Special tests such as a CT scan or MRI may be ordered and a consultation with a neurologist may be suggested.
TREATMENT AND PROGNOSIS
Most cases of optic neuritis have no specific treatment though steroids can sometimes speed up resolution of the inflammation. Fortunately the inflammation almost always improves on its own over a few months and vision recovers to almost normal usually by six months.
If the condition seems to be getting worse instead of better you are more likely to be placed on oral or injectable steroids. Do not continue oral steroids for any longer than the instructions called for; such medications can cause serious side effects so their use must be carefully monitored.
Even after a full recovery some people may have other attacks later. Repeat attacks are more likely to result in greater damage to vision. They may also be an early sign of Multiple Sclerosis. Therefore if you should suffer a second attack either in the same eye or in the other eye a complete medical examination is warranted to help identify a medical or neurological cause.