Optic Neuritis
From The MS Information
Sourcebook, produced by the National MS Society.
Optic neuritis is inflammation or demyelination of the
optic nerve¾the nerve that transmits light and
visual images from the retina to the brain. Because the nerve is located
behind (“retro”) the globe of the eye, the condition is also known as
retrobulbar neuritis.
It has been estimated that about 55% of people with MS
will have an episode of optic neuritis. Frequently, it is the first symptom
of MS.
Acute
Blurring or Loss of Vision, Usually in One Eye
Optic neuritis is generally experienced as an acute
blurring, graying, or loss of vision, most often in only one eye. It is rare
that both eyes are affected at the same time. There may or may not be pain in
the affected eye. Loss of vision usually reaches its maximum extent within a
few days, and generally improves within 4 to 12 weeks without treatment.
Recent studies suggest that a short course of
methylprednisolone administered intravenously, sometimes followed by a
tapered course of oral steroids may be useful in helping to reverse the
inflammation and restore vision more quickly. There is, however, no
definitive evidence that treatment with steroids produces a more complete
recovery than that which would have happened without treatment.
It
is Possible to Have Optic Neuritis Without Affecting Vision
A person may have a subclinical episode of optic neuritis.
That is, there may be inflammation and/or demyelination of the optic nerve
that occurs without affecting visual function so that the person is not aware
of any changes. In these subclinical cases, visual evoked potentials¾
electrical diagnostic tests¾are still able to demonstrate
evidence of lesions¾or damaged areas¾along
the optic pathways. It is for this
reason that visual evoked potentials are often used as part of the diagnostic
workup; a positive finding can provide evidence of a second demyelinating
event even in the absence of visual symptoms.
Not
Everyone Who Experiences Optic Neuritis Develops MS
Not everyone who has an episode of optic neuritis goes on
to develop MS. Long-term follow-up
from the Optic Neuritis Treatment Trial, which involved 388 people with a
single episode of optic neuritis, yielded the following:
- The
ten-year risk of developing clinically definite MS following a single
episode of optic neuritis was 38% for the entire study group; the twelve-year
risk was 40%. Most of those who
developed MS did so within the first five years after the initial
episode of optic neuritis.
- The
strongest predictor of MS in the study group was the presence of brain
lesions on MRI at the time of the episode of optic neuritis. Within the study group, patients with
at least one brain lesion on MRI at the time of the optic neuritis
episode had a 56% risk of developing MS within 10 years, while those
with no brain lesions had only a 22% risk of developing MS within 10
years.
While other disease processes can cause optic neuritis, MS
is the most likely cause in a young, otherwise healthy individual.
 Cerebrospinal Fluid (CSF)
Diagnosis
Evoked Potentials
Symptoms
Visual Loss
Visual Symptoms
Last
updated August 2003
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