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.

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 Disk Swelling

A doctor checks into the eye with an ophthalmoscope when there are regular complaints of headache, nausea or vomiting. This is to check for the appearance of the optic nerve and the blood vessels that pass through the eye. Swelling of the optic nerve is called Papilledema.

The optic nerve is a thick cord that connects the back of each eyeball and its retina to the brain. The cerebral spinal fluid protects the nerve between the brain and eye. Even if there is a slight increase in the pressure of this fluid, due to swelling in the brain, the optic nerve can get compressed around its whole circumference in a choking manner. The optic nerve can bulge whenever it develops inflammation on its own - causing Papilledema.

Such swelling of the optic nerve head can also be caused due to intracranial pressure. This could be due to an underlying brain tumor or brain infection such as abscess, meningitis or encephalitis. In fact many who are diagnosed with brain tumors exhibit Papilledema. Sometimes this can be caused due to high blood pressure.

Causes of Papilledema :

• Tumor of the Brain, Skull, Spinal column or cord, optic nerve
  
• Hydrocephalus - accumulation of cerebrospinal fluid within the skull
  
• Intracranial infections such as encephalitis, meningitis
  
• Abscess - Accumulation of Pus, Hemorrhage or trauma to the head
  
• Craniosynostosis - Abnormal closure of the skull bones
  

Symptoms of Papilledema :

• Headaches - especially the types which become severe on awakening; headaches that become exacerbated by coughing or holding breath
  
• Nausea and Vomiting
  
• Changes in vision manifesting in the form of double vision, flickering, transient blurring or graying
  

Pseudo tumor cerebri or benign intracranial hypertension is one condition which can cause increased pressure in the cerebral spinal fluid. This is caused when the body makes too much spinal fluid. This is common in women especially who are obese and of child bearing age, and at such times when the body is adjusting to hormone changes such as pregnancy, the first menstrual period or menopause. It is better to go in immediately for neuro-imaging and MRI to check the cerebral cenous sinuses. A lumbar puncture could be done to check the opening pressure as well as CSF (cerebro spinal fluid) test, Fluorescein Angiography - an eye test specifically intended to check the blood flow in the Retina and Choroid, if there is diagnostic uncertainty. In some cases ultrasonography and Retinal Tomography may be used to get 3D data and image.

Although a swollen optic nerve tends to improve over a period of time, it may take months for complete restoration of normal vision. Doctors usually treat with intravenous steroid drugs but this process may have little effect on vision in some cases, although it may help to improve overall health.