Vision
A problem with vision is one of the most common symptoms of
MS, and often one of the first people notice. The symptoms can include blurred
vision, double vision (diplopia), optic neuritis, involuntary rapid eye
movement and occasionally, a total loss of sight.
Why does MS cause
visual problems?
Problems with vision can result from damage to the optic
nerve or from an in-coordination in the eye muscles. The optic nerve connects
the eye to the brain. Inflammation or demyelination in the optic nerve causes
optic neuritis, which is experienced as a temporary loss or disturbance in
vision and possibly pain behind the affected eye.
Typically, vision returns partially or fully within a few
weeks. While it is quite rare for a person with MS to become totally blind, it
is not at all uncommon for an individual to have recurrent episodes of optic
neuritis over the course of the disease, usually in one eye at a time. Damage
to the optic nerve can result in a blurring of vision, which may or may not
totally resolve over time. Colour vision requires a great many nerve fibres
from the eye for accurate transmission and is particularly susceptible to
changes from demyelination.
Optic neuritis can cause a large, noticeable "blind
spot" in the centre of the visual field, and the person experiences a
visual image with a dark, blank area in the middle. This is called a central
scotoma and is not correctable with either eyeglasses or medication, although
steroids may be helpful in the early, acute phase.
Diplopia (double vision), the experience of seeing two of
everything, is caused by weakening or incoordination of eye muscles. This
symptom is typically treated with a short course of steroids. Patching one eye
while trying to drive or read will stop the double image; however, permanent
patching of the eye will slow the brain's remarkable ability to accommodate to
the weakness and produce a single image in spite of the weakened muscles.
Upon examination, the physician may detect a rhythmic
jerkiness or bounce in one or both eyes. This relatively common visual finding
in MS is nystagmus. Nystagmus does not always cause symptoms of which the
person is aware.
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