Optic Neuritis

Sudden inflammation of the optic nerve resulting in reduced vision in the affected eye is 'optic neuritis'. In particular, the myelin lining of the optic nerve which transmits visual stimuli to the brain is inflamed. As it is the optic nerve that carries visual information from the retina to the brain stem, vision is affected when the optic nerve is impaired. Optic Neuritis is also called Retro-bulbar neuritis.

Although the precise cause of Optic Neuritis is unknown, it is an autoimmune disorder. It usually occurs in children and young adults below 40 years of age. It can involve one or both optic nerves. It is more common in females. The annual incidence is approximately 6.4 / 100,000. Studies also reveal that about 1 in 5 patients who have had a first episode of optic neuritis are likely to develop nerve problems elsewhere in the body, or will develop multiple sclerosis.

Normally, the body's immune system fights infection by creating a reaction that can combat viruses, bacteria, fungi and others. But in autoimmune diseases, this reaction is directed against a normal part of the body instead of the inflamed part. In case of Optic Neurosis, there occurs inflammation and destruction of the protective myelin sheath that insulates the optic nerve by coating it and direct damage to the nerve axons leads to loss of vision.

In Optic Neurosis, the loss of vision can be sudden or develop gradually over a period of time. Vision loss may be partial or complete or may be only a certain part of the visual field. It is recommended that a person experiencing a first episode of Optic Neuritis undergo MRI of the brain. This can help identify for central nervous system lesions and the MRI can reveal an enlarged optic nerve. Other symptoms include loss of vision in one eye even for an hour, loss of color vision (achromatopsia), changes in pupil's reaction to bright light, and pain when the eye is moved.

Appropriate therapy is instituted depending upon the underlying cause of the infection in case of other autoimmune diseases. In some cases there can be no conclusive treatment as even oral and intravenous steroids, when used in treatment, do not have any long-term acuity and instead risks of side effects can be significant in some patients.

However, there are chances that normal vision returns within 2 to 3 weeks with no treatment. Corticosteroids given intravenously may speed up recovery whereas oral steroids may increase the chance of recurrence. Further evaluation can determine the cause of Neuritis and the underlying condition causing the problem can be treated.

Optic Neuritis

Optic neuritis is a condition where the optic nerve gets inflamed. Due to the inflammation, light and visual images are not clearly transmitted to the brain. Optic neuritis can be caused by autoimmune diseases such as multiple sclerosis or viral infections such as chicken pox or measles. Optic neuritis is usually the first sign of multiple sclerosis. This condition tends to affect more women than men.

Patients suffering from optic neuritis notice reduced vision. This is more so when the body temperature is elevated. The eyes are sore and painful when moved. There is reduced color perception and diminished peripheral vision. Persons suffering from optic neuritis may have headache and fever. The vision diminishes for about a week and then gradual improvement is noticed. Typically most patients suffering from optic neuritis tend to recover most of their vision within about 6 months.

The ophthalmologist will test the patient's color vision and visual field. Eye pressure and pupillary function will be examined. The optic disc is viewed with indirect ophthalmoscopy. Brain MRI may be taken for testing for multiple sclerosis. Intravenous steroid medication has shown results on those suffering from initial occurrence of optic neuritis.

Optic atrophy

Optic atrophy is the result of the fibres of optic nerve failing to transmit the visual information to the brain due to the damaged optic nerve which may result in problems with vision. Optic atrophy refers to the loss or damage of the fibres of the optic nerve. Optic nerve is responsible for carrying images from the eye to the brain. Optic atrophy presents itself with pale appearance of the optic nerve head at the back of the eye; hence this condition is also referred to as optic nerve head pallor. Although optic atrophy affects one eye, bilateral optic atrophy can also occur when the illness damages the nerves of the both eyes.

What causes optic atrophy ?

Optic atrophy is a serious eye disorder that is caused by a underlying disease or condition. Few of the diseases originating in the eye and the nervous system that lead to optic Atrophy are given below.

• Compression of the optic nerve.
  
• Glaucoma or high pressure within the eye.
  
• Infection
  
• Multiple sclerosis
  
• Inflammation of the optic nerve called optic neuritis.
  
• Interruption in blood circulation to the optic nerve in the form of decreased blood supply (ischemia) or oxygen supply (hypoxia).
  
• Tumors on the visual pathway
  
• Trauma
  
• Optic atrophy can even be inherited from parents.
  
• Nutritional deficiencies (especially B12), certain medications and exposure to certain toxins also lead to optic atrophy.
  

Symptoms of optic atrophy

If you face any of these symptoms seek medical attention immediately as any progression of optic atrophy leads to vision loss. Though the occurrence of these symptoms does not necessarily mean optic atrophy, it is always better to rule out this severe eye condition. Ophthalmologist will examine the eyes with an ophthalmoscope and the doctor may recommend few more tests, if he suspects optic atrophy. Tests such as tonometry, pupil light reflex, color vision and visual acuity are conducted.

• Blurred vision
  
• Poor visual function such as low clarity of vision or visual acuity.
  
• Distorted peripheral vision.
  
• Problems in color vision
  
• Decreased brightness in the affected eye. Diminished reaction of the pupil to the light.
  
• Change in the optic disc

Treatment of optic atrophy

Currently there is no sure shot and effective treatment or therapy available for optic atrophy. However ophthalmologist diagnose the underlying condition or disorder that is causing optic atrophy and treat them. This will avoid the further damage of the optic nerve and preserve the existing vision.