Disease: Optic Neuritis
Optic neuritis facts
- Optic neuritis is an inflammation of the optic nerve, often affecting young adults in one eye.
- Optic neuritis is frequently associated with multiple sclerosis. Other causes include infections, autoimmune disease, and injury to the optic nerve.
- The symptoms of optic neuritis include vision loss, reduced color vision, and pain on movement of the eye with recovery over weeks to a month, in most cases.
- The diagnosis is made on the basis of the patient history and an examination by an ophthalmologist. An MRI is important to look for lesions that indicate the patient may develop multiple sclerosis. Blood tests may be indicated.
- High-dose IV corticosteroids speed up recovery, but appear to have no effect on the long-term outcome.
What is optic neuritis?
Optic neuritis is an inflammation that affects the myelin lining of the optic nerve, which transmits visual stimuli to the brain. The optic nerve is actually a nerve tract of axons that originate in the ganglion cells of the retina. Nerve tracts are the information pathways in the brain. The "optic nerves" are the only nerve tracts not located entirely within the brain. The optic nerves carry visual information from the retina to the brain stem, where the information is relayed to the area of the brain that recognizes vision (the occipital cortex).
Optic neuritis can occur in children or adults and may involve either one or both optic nerves. Optic neuritis typically affects young adults ranging from 20 to 40 years of age. There is a strong female predominance. The annual incidence is approximately 6.4/100,000.
What causes optic neuritis?
The precise cause of optic neuritis is unknown, but it is thought to be a type of autoimmune disorder. The immune system is generally used to fight infection by creating a reaction that combats bacteria, viruses, fungi, and other foreign proteins. In autoimmune diseases, this reaction is mistakenly directed against a normal part of the body, creating inflammation and potential damage. In the case of optic neuritis, the optic nerve becomes swollen and its function is impaired. Inflammation and destruction of the protective myelin sheath that coats and insulates the optic nerve, plus direct damage to the nerve axons results in loss of vision.
Optic neuritis is frequently an indication of multiple sclerosis (MS), a disease in which the immune system attacks the myelin sheath covering nerve fibers in the brain and spinal cord, resulting in inflammation and nerve damage. Optic neuritis typically resolves initially, but recurs.
In 15%-20% of people who eventually develop multiple sclerosis, optic neuritis is their first symptom. The risk of developing multiple sclerosis following one episode of optic neuritis is approximately 50% within 15 years of the episode of optic neuritis. Studies vary, but between 27% and 70% of patients who have optic neuritis for the first time will have 2 or more MRI abnormalities consistent with MS. The 5-year risk of developing multiple sclerosis is 16% if the MRI is negative, 51% if there are 1 to 3 lesions.
Neuromyelitis optica is another autoimmune condition in which demyelination mainly occurs in the spinal cord and optic nerve, but is less noticeable in the brain. In this infrequent condition, the patient can experience weakness or paralysis in the limbs and/or bladder and bowel dysfunction, as well as loss of vision.
There are a variety of conditions that can affect the optic nerve causing symptoms similar to optic neuritis (optic neuropathies).
Infection, trauma, hereditary conditions, toxic or nutritional problems, compressive lesions, arteritis, diabetes, glaucoma, etc. Treatment of optic neuropathies associated with these patients depends on the cause, and is directed at the underlying disease.
What are symptoms of optic neuritis?
The major symptom of optic neuritis is vision loss, usually in one eye, often developing within hours to a couple of days and peaking in 1 to 2 weeks. It may vary from a small area of blurring to complete blindness. Affected individuals may also notice distorted vision, reduced color vision, loss of contrast, and washed-out or less vivid vision than normal. Symptoms may be worsened by heat or exercise. Vision loss is usually temporary, but it may be permanent in some cases.
Most people who develop optic neuritis experience eye pain that is worsened by eye movement. The intensity of the pain usually follows the course of the vision loss.
Because optic neuritis usually affects one eye, patients may be unaware of subtle visual loss or changes in the color vision until they or doctors close or cover the healthy eye.
What are signs of optic neuritis?
The most characteristic findings on examination include reduced visual acuity (typically 20/25 to 20/190), a measurable change in peripheral vision, decreased perception of brightness in the affected eye, and loss of color vision out of proportion to the loss of visual acuity. A disturbance in reaction of the pupil (afferent pupillary defect or APD) is usually detectable if the other eye is either unaffected or involved to a lesser degree.
The optic nerve can easily be visualized with an ophthalmoscope. In one-third of the cases, there is visible swelling of the optic nerve, and there may be enlargement of the blood vessels around the nerve. This condition is called papillitis. In about two-thirds of patients, inflammation is entirely retrobulbar, causing no visible changes when the physician examines the optic nerve with an ophthalmoscope. This is called retrobulbar neuritis.
How is optic neuritis diagnosed?
Optic neuritis is suspected based on the characteristic history of eye pain and vision loss. The standard exam includes visual acuity, pupillary reduction, visual field evaluation, color vision testing, and visualization of the optic disc by direct and indirect ophthalmoscopy.
A person experiencing a first episode of optic neuritis should undergo an MRI of the brain to look for the central nervous system lesions associated with MS. The MRI may also show an enlarged optic nerve.
Visual symptoms usually progress for the first couple weeks, and then start to improve within the first month. If the course of recovery is not typical, then there are a number of blood tests like the sed rate, thyroid function, antinuclear antibodies, etc. that can be performed to look for other causes of optic neuritis/neuropathy.
What is the treatment for optic neuritis?
If a definite cause (such as infection or underlying other disease) is determined, appropriate therapy for that cause can be instituted.
The Optic Neuritis Treatment Trial, a multicenter randomized trial with 15 years of follow-up, showed that oral steroid (prednisone) alone, had no benefit on recovery to normal visual acuity. High-dose intravenous steroids, which involve some risks and can have significant side effects in some patients - e.g. elevated blood sugar, depression, insomnia, gastrointestinal symptoms, etc. - did speed up the initial recovery of vision in the acute phase. However, there was no conclusive evidence that oral or intravenous steroids had any long-term benefit on visual acuity, visual field or contrast sensitivity five years later.
What causes optic neuritis?
The precise cause of optic neuritis is unknown, but it is thought to be a type of autoimmune disorder. The immune system is generally used to fight infection by creating a reaction that combats bacteria, viruses, fungi, and other foreign proteins. In autoimmune diseases, this reaction is mistakenly directed against a normal part of the body, creating inflammation and potential damage. In the case of optic neuritis, the optic nerve becomes swollen and its function is impaired. Inflammation and destruction of the protective myelin sheath that coats and insulates the optic nerve, plus direct damage to the nerve axons results in loss of vision.
Optic neuritis is frequently an indication of multiple sclerosis (MS), a disease in which the immune system attacks the myelin sheath covering nerve fibers in the brain and spinal cord, resulting in inflammation and nerve damage. Optic neuritis typically resolves initially, but recurs.
In 15%-20% of people who eventually develop multiple sclerosis, optic neuritis is their first symptom. The risk of developing multiple sclerosis following one episode of optic neuritis is approximately 50% within 15 years of the episode of optic neuritis. Studies vary, but between 27% and 70% of patients who have optic neuritis for the first time will have 2 or more MRI abnormalities consistent with MS. The 5-year risk of developing multiple sclerosis is 16% if the MRI is negative, 51% if there are 1 to 3 lesions.
Neuromyelitis optica is another autoimmune condition in which demyelination mainly occurs in the spinal cord and optic nerve, but is less noticeable in the brain. In this infrequent condition, the patient can experience weakness or paralysis in the limbs and/or bladder and bowel dysfunction, as well as loss of vision.
There are a variety of conditions that can affect the optic nerve causing symptoms similar to optic neuritis (optic neuropathies).
Infection, trauma, hereditary conditions, toxic or nutritional problems, compressive lesions, arteritis, diabetes, glaucoma, etc. Treatment of optic neuropathies associated with these patients depends on the cause, and is directed at the underlying disease.
What are symptoms of optic neuritis?
The major symptom of optic neuritis is vision loss, usually in one eye, often developing within hours to a couple of days and peaking in 1 to 2 weeks. It may vary from a small area of blurring to complete blindness. Affected individuals may also notice distorted vision, reduced color vision, loss of contrast, and washed-out or less vivid vision than normal. Symptoms may be worsened by heat or exercise. Vision loss is usually temporary, but it may be permanent in some cases.
Most people who develop optic neuritis experience eye pain that is worsened by eye movement. The intensity of the pain usually follows the course of the vision loss.
Because optic neuritis usually affects one eye, patients may be unaware of subtle visual loss or changes in the color vision until they or doctors close or cover the healthy eye.
What are signs of optic neuritis?
The most characteristic findings on examination include reduced visual acuity (typically 20/25 to 20/190), a measurable change in peripheral vision, decreased perception of brightness in the affected eye, and loss of color vision out of proportion to the loss of visual acuity. A disturbance in reaction of the pupil (afferent pupillary defect or APD) is usually detectable if the other eye is either unaffected or involved to a lesser degree.
The optic nerve can easily be visualized with an ophthalmoscope. In one-third of the cases, there is visible swelling of the optic nerve, and there may be enlargement of the blood vessels around the nerve. This condition is called papillitis. In about two-thirds of patients, inflammation is entirely retrobulbar, causing no visible changes when the physician examines the optic nerve with an ophthalmoscope. This is called retrobulbar neuritis.
How is optic neuritis diagnosed?
Optic neuritis is suspected based on the characteristic history of eye pain and vision loss. The standard exam includes visual acuity, pupillary reduction, visual field evaluation, color vision testing, and visualization of the optic disc by direct and indirect ophthalmoscopy.
A person experiencing a first episode of optic neuritis should undergo an MRI of the brain to look for the central nervous system lesions associated with MS. The MRI may also show an enlarged optic nerve.
Visual symptoms usually progress for the first couple weeks, and then start to improve within the first month. If the course of recovery is not typical, then there are a number of blood tests like the sed rate, thyroid function, antinuclear antibodies, etc. that can be performed to look for other causes of optic neuritis/neuropathy.
What is the treatment for optic neuritis?
If a definite cause (such as infection or underlying other disease) is determined, appropriate therapy for that cause can be instituted.
The Optic Neuritis Treatment Trial, a multicenter randomized trial with 15 years of follow-up, showed that oral steroid (prednisone) alone, had no benefit on recovery to normal visual acuity. High-dose intravenous steroids, which involve some risks and can have significant side effects in some patients - e.g. elevated blood sugar, depression, insomnia, gastrointestinal symptoms, etc. - did speed up the initial recovery of vision in the acute phase. However, there was no conclusive evidence that oral or intravenous steroids had any long-term benefit on visual acuity, visual field or contrast sensitivity five years later.
Source: http://www.rxlist.com
Source: http://www.rxlist.com
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