Optic Neuritis

Optic neuritis (or retrobulbar neuritis ) is the inflammation of the optic nerve which may cause a blooming or partial loss of vision. It is a variable condition and can present with any of the following symptoms: blurring of vision, loss of visual acuity, loss of some or all colour vision, overall or partial blindness and pain behind the eye. The visual deficit may sink over a period of approximately 7 days, then typically remains braced (at that level) for 3 to 8 weeks, followed by gradual visual improvement. The great majority of patients having optic neuritis will retrieve much of their vision within 6 months of the onset of optic neuritis. It is not uncommon to have an occurrence of optic neuritis prior to being diagnosed with MS.

Most patients having optic neuritis experience a abrupt onset of decreased vision along with pain and soreness when moving the eye. Indeed, for this group, ON is often a fallacious diagnosis and the cause is often ischemic optic neuropathy or some other condition. Testing peripheral vision may divulge loss of vision at the periphery (side) of the visual field. Magnetic resonance imaging (MRI) may show corroboration of multiple sclerosis or, rarely, a tumor pressing on the optic nerve. The nerve of one or both eyes may be affected. Some people, especially children, develop optic neuritis following a viral illness such as mumps, measles or a cold. Optic neuritis often affects only one eye and may be a recurring complication with certain diseases such as MS. 

Optic neuritis refers to swelling or inflammation of the optic nerve. There is also customarily a history of pain with eye movement, and this may precede the visual loss. Pathological studies in patients with ON conjoining with MS have shown that the demyelinative lesions in the optic nerve are similar to the MS plaques seen in the brain, with an inflammatory response marked by perivascular cuffing, T cells, and plasma cells. In fact, optic neuritis is usually the initial sign of MS. With optic neuritis, the optic nerve becomes swollen and the nerve fibers do not work properly. Vision can differ from near normal to very poor depending on the number of inflammed nerve fibers. Vision in the involved eye or eyes can range from almost normal to complete blindness. There may be pain with eye movement. Depending on the cause, vision may recover only to deteriorate later in reiterate episodes of worsening vision. It is not uncommon to have an episode of optic neuritis prior to being diagnosed with MS.

Causes of optic Neuritis

The common causes of optic Neuritis :

• The inflammation may occasionally be the result of a viral infection, or it may be caused by autoimmune diseases such as multiple sclerosis .
• Sudden inflammation of the optic nerve (the nerve connecting the eye and the brain) leads to swelling and ruination of its outer shell, called the myelin sheath.
• Various eye diseases, most commonly glaucoma, can also cause optic nerve atrophy.
• There are several unrelated causes of optic atrophy.
• There are also several rare forms of hereditary optic nerve atrophy which strikes children and young adults.
• An attack on the optic nerve by a viral infection or by the body's own immune system
• The ophthalmoscopic appearance of the disk in papillitis and papilledema may be similar, but papillitis often causes expressive vision loss, and usually a swoon vitreous haze caused by cellular and fluid exudation from the inflamed area, with some opacification of the inner surface of the disk.

Symptoms of optic Neuritis

Some common symptoms of optic Neuritis :

• Blurred vision in one or both eyes (especially after exercising or taking a hot bath)
• Dim vision (as if the lights were turned down)
• Abnormal color vision (dull and faded colors)
• Loss of color vision
• Tender, sore eye
• Pain on movement of the eye
• Decreased constriction of the pupil of the affected eye in bright light
• Headache
• Nausea
• Acute loss of vision in one eye

Treatment of optic Neuritis

• Visual acuity often returns to normal within 2 - 3 weeks with no treatment.
• Optic nerve atrophy can be promptly detected on complete examination of the eyes.
• Seeking the cause may require a complete physical examination and certain tests.
• Further tests may be needed to arbitrate the cause of the neuritis, and the condition causing the complication would then be treated.
• Intravenous corticosteroid therapy may expedite visual recovery but may be associated with systemic side effects.
• While this treatment has little if any impact on vision, it is necessary for overall health.
• Oral corticosteroid therapy may increase the risk of recurrence and is rarely used for initial therapy.
• Intravenous steroids (methylprednisolone 250 mg qid for 3 d with oral steroid taper) decreased the short-term risk of development of MS in patients with CNS white matter plaques, but had no long-term protective benefit from MS.
• Admission to the hospital is recommended for the duration of high-dose intravenous steroid treatment because of the potential risk of serious adverse effects from this treatment.