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What is Adult Strabismus?
Strabismus is a condition in which the
eyes are misaligned and point in different directions. Adult
strabismus occurs in approximately one percent of the population.
What causes adult strabismus?
Most adult strabismus is simply persistent
childhood strabismus. Strabismus which occurs in adulthood without a
history of childhood strabismus should be carefully evaluated for
medical or neurological causes such as diabetes, thyroid disease,
myasthenia gravis, brain tumors or strokes.
What are the symptoms of adult strabismus?
If strabismus has been present since
childhood, symptoms are usually minimal. If the strabismus develops
in late childhood or adulthood, the most common symptom is double
vision. Some adults with strabismus will have eye strain, discomfort
with reading, headaches, or may even or turn or tilt their head to use
their eyes together. Children and adults who turn their eyes outward
(exotropia) often squint or close one eye in bright sunlight.
What causes double vision?
When the eyes are misaligned, each eye
sees a separate image. Infants and children whose eyes are misaligned
can learn to suppress or ignore the image from one eye and
consequently avoid seeing a double image. However, adults are unable
to suppress one image. The resulting double vision can be relieved by
closing one eye, wearing a patch, or aligning the eyes.
How is adult strabismus treated?
There is a common misconception that
strabismus in adults is difficult or impossible to treat. Actually,
adults with strabismus have many treatment options including eye
exercised, prism glasses, eye muscle surgery and botulinum toxin
injections.
Eye muscle exercises may be helpful in
treating special problems such as convergence insufficiency, a
condition in which the eyes do not function well for close work or
reading.
Glasses with prisms are most useful for
correcting small deviations. Images are realigned by the prisms to
compensate for the misalignment of the eyes and may relieve double
vision.
The eye muscle can be injected with
botulinum toxin, a drug that is used to paralyze the muscle. The
temporary effect wears off in a few months but may result in permanent
change in the eye alignment. This technique is useful in very
specific cases usually associated with nerve palsies.
Eye muscle surgery is the most common
treatment for strabismus at any age. Muscles are either tightened or
weakened by repositioning them on the eyeball to better align the two
eyes. Please see our section on muscle surgery for additional
information.
Usually strabismus surgery is performed
under general anesthesia, but some cases can be done with local
anesthesia.
The use of a special surgical technique
allows some post-operative adjustment of eye alignment, by using
adjustable sutures. The operation is performed in two stages. The
first stage one or more of the muscles are repositioned with ãslip
knotä sutures.
The second phase is usually performed some
hours later, or even on the following day with a topical anesthetic.
If small realignments are necessary, the ãslip knotä suture allows
adjustment to be made. This technique requires cooperation from the
patient and is not suitable for everyone.
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