Optic Neuritis: Symptoms, Causes, Treatment

Introduction

Causes of Optic Neuritis

The exact cause of optic neuritis remains unknown. Medical science believes it may be a form of autoimmune disorder. A person's immune system generally fights infections by creating a reaction that fights viruses, bacteria, fungi, and additional foreign proteins. Where autoimmune diseases are concerned, however, this reaction on the part of a person's immune system is mistakenly directed against a part of the person's body, causing inflammation and, potentially, damage. Where optic neuritis is concerned, the person's optic nerve becomes inflamed and its function impaired. The inflammation causes the person to experience a loss of vision due to the swelling and destruction of the protective myelin sheath that both covers and insulates their optic nerve. Damage to the person's axons can also occur, resulting in nerve destruction.

The U.S. Social Security Administration (SSA) has included Bilateral Optic Atrophy - Infantile as a Compassionate Allowance to expedite a disability claim.

Main Digest

For some people, the signs and symptoms of optic neuritis might be an indication of multiple sclerosis, a disease involving immune system attacks on the person's myelin sheath covering nerve fibers in their brain and spinal cord, which results in inflammation and damage to the person's nerve cells in their spinal cord and brain. Another term for this condition is 'demyelinating optic neuritis.' People affected by optic neuritis resulting from demyelinating disease, multiple sclerosis, in particular, might experience recurrences of optic neuritis over time.

Among people who eventually develop multiple sclerosis, between fifteen and twenty-percent experience optic neuritis as a first symptom. The risk of developing multiple sclerosis after a single episode of optic neuritis is around fifty percent within fifteen years of the episode of optic neuritis. After receiving an MRI scan, nearly half of the people with optic neuritis present with abnormal brain white matter changes consistent with multiple sclerosis. In people who received MRI scans as they were experiencing an initial attack of optic neuritis, the finding of brain lesions on MRI images increased the risk of developing later multiple sclerosis by three times over people with average MRI scan results. Nearly half of people with brain lesions on MRI results at the initial episode of optic neuritis have not developed multiple sclerosis even ten years later.

One other autoimmune condition that causes optic neuritis is 'neuromyelitis optic.' The condition is considered unusual and causes inflammation in the optic nerve and spinal cord, although not usually within the person's brain as often as multiple sclerosis. Optic neuritis resulting from neuromyelitis optics is often more severe than the optic neuritis people experience in association with multiple sclerosis. Several causes of optic neuritis are not associated with multiple sclerosis. Among these causes are the following:

• Autoimmune Diseases: Autoimmune diseases, such as systemic lupus, might cause inflammation of blood vessels that nourish the optic nerve.
• Cranial Arteritis: Cranial arteritis involves an inflammation of the lining of the arteries within the skull. Inflammation of cranial arteries may block blood flow to a person's eyes and brain, leading to permanent vision loss or stroke. Cranial arteritis is also known as GCA.
• Diabetes: Diabetes is when a person's body cannot make or appropriately use insulin, a hormone that regulates sugar in the blood and other tissues. People with diabetes are at an increased risk of developing disorders of their optic nerve, including optic neuritis.
• Drugs: Some drugs have been associated with the development of optic neuritis, including ethambutol and some antibiotics.
• Infections: Bacterial infections, such as tuberculosis, Lyme disease, toxoplasmosis, cat scratch fever, and syphilis, as well as viral infections including hepatitis B, HIV, and herpes zoster, may cause optic neuritis. Encephalitis, bacterial meningitis, and sinusitis can cause optic neuritis as well.
• Lebers Hereditary Optic Neuropathy: Leber's hereditary optic neuropathy is an inherited form of vision loss that largely affects males in their twenties and thirties and can cause optic neuritis.
• Radiation Therapy: Radiation therapy administered to a person's head is an uncommon cause of optic neuritis.
• Sarcoidosis: As well as pernicious anemia, Graves disease, bee stings, and vaccinations, mall all cause vision loss from swelling of the person's optic nerve.
• Toxins: Methy alcohol, lead, arsenic, and quinine can cause vision loss and additional symptoms which mimic optic neuritis.

Optic neuropathy describes any condition that damages a person's optic nerve. Optic neuritis itself is a particular type of optic neuropathy that is the result of inflammation. Some of the common, noninflammatory causes of optic neuropathy include:

• Injuries
• Glaucoma
• Toxic exposure
• Neurological disease
• Nutritional deficiencies
• Intraocular inflammation
• Blocked or limited blood flow
• Elevated intracranial pressure
• Direct trauma to the optic nerve
• Primary and metastatic optic nerve tumors

Trauma may interfere with the nerve's ability to conduct electrical impulses. These can cause a person to experience vision loss and additional symptoms that mimic optic neuritis.

Symptoms of Optic Neuritis

The most characteristic signs a doctor finds after examining someone include a reduction in their visual accuracy, a measurable change in their peripheral vision, a decrease in their perception of brightness in the eye that is affected, as well as a change in the person's color vision - something that is often out of proportion to their loss of visual acuity. There is also a detectable disturbance in the function of the person's pupil if the person's other eye is either unaffected or is involved but to a lesser degree.

The main symptom of optic neuritis is loss of vision, which occurs within one or two days and varies from a small area of blurring to complete blindness. People affected by optic neuritis might also experience distorted vision, loss of contrasts, reduced color vision, and vision that is 'washed out or less vivid than usual. The vision loss commonly develops over a day or two but may take up to two weeks and could be worsened by exercise or heat. The vision loss is usually temporary, although it may sometimes be permanent.

Most people who develop optic neuritis experience eye pain that worsens when moving their eyes. The pain associated with optic neuritis commonly peaks within a week and disappears within several days. Optic neuritis usually affects only one person's eyes, although it can simultaneously affect both of a person's eyes. At times when only one of a person's eyes is affected, people might be unaware of subtle visual loss or changes in their color vision until a doctor asks them to close or cover their healthy eye.

Diagnosing Optic Neuritis

Optic neuritis is something a doctor suspects as a diagnosis in people who experience characteristic eye pain and vision loss. A doctor will pursue a complete medical examination, including a chemical analysis of the person's blood, to rule out any related diseases. The tests might include pupillary testing, visual acuity testing, color vision testing, visual field testing, and visualization of the person's optic disc directly or indirectly through ophthalmoscopy.

People experiencing their first episode of optic neuritis commonly undergo an MRI of their brain to look for central nervous system lesions. An MRI exam with gadolinium enhancement might reveal an enlarged, enhancing optic nerve. An MRI can also assist in diagnosing multiple sclerosis by revealing typical abnormalities in the person's brain.

Treatment of Optic Neuritis

Should a doctor find a definite cause, such as a disease or an infection, they can treat the disease or infection. Suppose the person's optic neuritis is due to something that cannot be determined or is related to multiple sclerosis. In that case, the person's vision often returns to usual within two to twelve weeks without treatment. However, it could also advance to a permanent state of either partial or total vision loss.

Treatment with steroid medications such as Deltasone, Orason, Prednison, Methylprednisolone, or others can speed up the person's vision recovery time. While treatment with steroids has little effect on the end visual outcome of people with optic neuritis, people who receive initial treatment with intravenous steroids have around half the risk of developing multiple sclerosis in two years compared with those who do not receive such treatment. The effect disappears by the third year of follow-up. People who receive intravenous steroid treatment experience fewer repeated attacks of optic neuritis than people who do not. Intravenous steroid treatment is commonly followed by approximately eleven days of oral steroids. When optic neuritis is associated with MRI lesions that are suggestive of multiple sclerosis, immunosuppressive or immunomodulator therapy might be prescribed to reduce the number of future attacks.

Author Credentials:

Thomas C. Weiss is a researcher and editor for Disabled World. Thomas attended college and university courses earning a Masters, Bachelors and two Associate degrees, as well as pursing Disability Studies. As a Nursing Assistant Thomas has assisted people from a variety of racial, religious, gender, class, and age groups by providing care for people with all forms of disabilities from Multiple Sclerosis to Parkinson's; para and quadriplegia to Spina Bifida. Explore Thomas' complete biography for comprehensive insights into his background, expertise, and accomplishments.

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Cite This Page (APA): Weiss, T. C. (2010, April 14). Optic Neuritis: Symptoms, Causes, Treatment. Disabled World. Retrieved May 19, 2024 from www.disabled-world.com/disability/types/vision/optic-neuritis.php

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