Optic neuritis

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at September 6, 2016
StartDiseasesOptic neuritis

A sudden change in eyesight, such as blurred vision or tunnel vision or the inability to distinguish colors (color blindness) can be alarming, especially when accompanied by pain. Symptoms such as these may be a sign of optic neuritis, a demyelinating disease that affects the optic nerve, which delivers visual signals from the eye to the brain

Contents

Definition & Facts

Optic neuritis occurs when the eye’s optic nerve becomes inflamed. Swelling of the eye and short-term loss of vision results. Optic neuritis may occur in both eyes at the same time, but normally only affects one eye in adults.

Optic neuritis occurs when a person’s immune system begins to attack the myelin that covers the optic nerve. The immune response may be triggered by a viral infection or it may be related to unknown factors.

Myelin is a protective material that surrounds the nerve fibers located in the brain and spinal cord. Any condition that results in damage or deterioration of myelin is known as a demyelinating disease. People with the following characteristics have the highest risk of developing optic neuritis:

  • Those with a family history of multiple sclerosis or those who have been diagnosed with multiple sclerosis
  • Those living in a high altitude climate
  • Caucasians
  • Young adults between twenty and forty years of age
  • Women

Symptoms & Complaints

The first sign of optic neuritis that most people notice is vision loss, which may include difficulty differentiating colors. Their vision may appear blurry, or they may not be able to see at all out of one eye.

Patients with optic neuritis may also experience a headache and pain in the eye, particularly when they are looking around, and many people report flashing lights similar to those people experience with migraine headaches. Fatigue, exercise, and heat may exacerbate the symptoms. 

The more severe the inflammation in the optic nerve, the more severe the symptoms will be. Because optic neuritis often results from a viral infection, people with optic neuritis may also experience other viral symptoms such as a fever.

Complications may result from optic neuritis, including permanent vision loss or nerve damage in other parts of the body. However, symptoms typically progress over a few days and start repairing within one to three months.

Causes

It can be hard to pinpoint the exact cause of optic neuritis as it is often a complication of other medical issues. Optic neuritis is associated with neuromyelitis optica as well as multiple sclerosis, and diagnosis of the disorder is often the first medical clue that someone has developed MS. 

Neuomyelitis optica typically involves damage to the spinal cord and is associated with a family history. The underlying mechanism that causes this disease involves malfunctioning antibodies.

Respiratory infections such as influenza, mumps, measles, diabetes mellitus, lupus, herpes, and mononucleosis can trigger an autoimmune response that attacks the myelin of the optic nerve as well.

Diagnosis & Tests

Individuals should make an appointment to see their ophthalmologist if they have unresolved eye pain, headaches, or blurry or reduced vision. The ophthalmologist will complete an eye examination which may include:

  • Identifying the extent of the vision impairment as well as assessing the patient's pupillary response (the pupil's reaction), color vision, and the peripheral vision
  • Testing the optic nerve through the use of an ophthalmoscopy in which the health care professional will shine a light into the pupil to examine the structures supporting the eye. 

The health care professional will also need to rule out or diagnose underlying causes of the optic neuritis, such as multiple sclerosis or other diseases. He or she may order medical imaging tests such as a computed tomography (CT) scan and magnetic resonance imaging (MRI) which can detect lesions in the brain and optic nerve.

Blood tests may also be ordered to rule out certain conditions. Such tests will assess erythrocyte sedimentation rate, thyroid function, and angiotensin-converter enzyme. A lumbar puncture (also known as a spinal tap) will test a person's cerebrospinal fluid.

Treatment & Therapy

Many people with optic neuritis regain their vision within one to three months and fully recover within a year with little or no remediating treatment. The patients may be prescribed corticosteroid medication, either orally or intravenously, to reduce inflammation and speed up the rehabilitation of the optic neuritis. Examples of steroids include methylprednisolone, dexamethasone, and prednisone.

The use of this steroid won’t help improve the final vision outcome after treatment and recovery. Use of steroidal medication may have side effects, such as osteoporosis, weight gain, immunodeficiency, insomnia, nausea, or mood swings

Treatment of any underlying infections through the use of antibiotics in the case of triggering bacterial infections and antiviral drugs in the case of triggering viral infections is important in ensuring that the optic nerves aren’t damaged permanently. 

Prevention & Prophylaxis

There is no proven way to prevent optic neuritis. The first line of attack is to see one's ophthalmologist regularly and immediately if one's vision changes drastically over a short period. 

Committing to a healthy lifestyle through a healthy diet, regular exercise, and practicing safe sex can also help an individual avoid some of the triggers of optic neuritis: respiratory infections, viral infections, diabetes mellitus type II, and HIV.

If a person is at high risk for multiple sclerosis, his or her doctor may recommend immunomodulators and immunosuppressive drugs which can help slow the progression of multiple sclerosis. Interferon beta-1b, interferon beta-1a, dalfampridine, alemtuzumab, glatiramer acetate are examples of immunomodulator drugs. An example of an immunosuppressive drug is methotrexate.