Optic Neuritis

The optic nerve transmits visual information from the eye to the brain. Optic neuritis is an inflammation of this nerve that can cause serious problems, including intense headaches and loss of vision. Infections such as Lyme disease, measles and mumps can cause optic neuritis, as can other disorders, such as lupus  or diabetes . Although the exact causes of optic neuritis are incompletely understood, there is a strong association with other conditions characterized by an autoimmune response, in which the immune system attacks a person’s own cells. Optic neuritis is often the first sign of the autoimmune disease multiple sclerosis  (MS); neuromyelitis optica is another disease that shares with MS the dual features of optic neuritis and myelitis (the medical name for inflammation of the spinal cord). 

Symptoms and Diagnosis
Symptoms of optic neuritis can include any of the following: 

• Pain in or behind the eye, especially as the eyes move 
• Vision loss or severe impairment 
• Loss of color vision (faded colors)
• Flashing lights 

Although there is no single definitive diagnostic test for optic neuritis, certain characteristics of the symptomology can be helpful in establishing the diagnosis:

• Usually only one eye is affected
• Symptoms progress over the course of hours to days – if symptoms progress for more than two weeks another disease may be responsible
• Vision begins to improve within a few weeks – if vision does not begin to improve within a month after the peak, another disease may be responsible

While full or partial vision loss is common in optic neuritis, most patients have their vision restored to functional levels within a year of the onset of the disease  .   

Some of the tests and procedures that can help to establish the diagnosis include the following: 

• Eye exams  – Your doctors will evaluate how well you see, including: 
  
  • Standard eye exam
  • Your ability to perceive colors
  • How quickly your pupils respond to a bright light (the response of the affected eye will be slower than the unaffected eye when a bright light is shined on it)
  • The appearance of the back of your eye when the doctor shines a bright light to examine the optic disk (area where the optic nerve enters the retina. Only about one in three people with optic neuritis will have visible damage in this area.
• Magnetic resonance imaging (MRI)of the brain and the orbits (sockets) of the eye are performed for two reasons:
  
  • To evaluate optic nerve damage
  • To check for lesions in the brain that may signal the risk of developing MS at a later date.  
• A blood test is available to check for the presence of antibodies that are associated with neuromyelitis optica.

Treating Optic Neuritis
Treatment of optic neuritits is directed at reducing the damaging immune response and inflammation. Generally patients are given a 3-day intravenous course of high doses of the anti-inflammatory agent prednisone. This treatment may speed the recovery of clear vision. It may also reduce the risk of developing MS over the next two years. For reasons that are not understood, the lower doses of steroids that are often used to reduce inflammation actually increase the risk of optic neuritis recurrence. 

For some of the possible causes of optic neuritis, treatment of the underlying disorder may help ease its effects.

The comprehensive management of optic neuritis from diagnosis through treatment may engage a wide range of medical specialties, each of which is available at Houston Methodist.