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Strabismus Strabismus,
also known as "heterotropia", "squint", "crossed eye", "wandering eye", or "wall
eyed", is a disorder in which the eyes do not point in the same direction. It
typically involves a lack of coordination between the extraocular muscles which
prevents bringing the gaze of each eye to the same point in space, preventing
proper binocular vision, which may adversely affect depth perception. The cause
of strabismus can be a disorder in one or both of the eyes; for example,
nearsightedness or farsightedness, making it impossible for the brain to fuse
two different images.
When strabismus is congenital or develops in infancy, it can
cause amblyopia, in which the brain ignores input from the deviated eye although
it is capable of normal sight. Since strabismus can cause amblyopia, which is
sometimes referred to as lazy eye, it is sometimes itself inaccurately
referred to as lazy eye.
In addition to the visual problem, strabismus can be
considered a cosmetic problem owing to the appearance of the deviated eye. One
study reported that 85% of adult strabismus patients "reported that they had
problems with work, school and sports because of their strabismus". The same
study also reported that 70% said strabismus "had a negative effect on their
self-image".
Types
Strabismus may be concomitant or incomitant.
Concomitant strabismus means that the strabismus is equal
regardless of which direction the gaze is targeted. This
indicates that the individual extraocular muscles function
individually, but that they may simply not be aimed at the same
target. Concomitant strabismus in a child under the age of 6
rarely indicates serious neurologic disorder. Blindness in one
eye usually causes concomitant strabismus, with the eye of a
child turning inward, and that of an adult turning outward.
Incomitant strabismus occurs when the degree
of misalignment varies with the direction of gaze. This
indicates that one or more of the extraocular muscles may not be
functioning normally. Types of strabismus include:
- esotropia, or one eye turning
inward.
- exotropia, or one eye turning
outward.
- hypertropia, or one eye turning
upward.
- hypotropia, or one eye turning
downward.
Medial strabismus manifests as the
inability to abduct (move laterally) one's eye. This is usually
caused by damage to the abducens nerve or abducens nucleus. The
result is that the eye in its normal resting state deviates
medially, as the movements of the medial rectus muscle are less
opposed by the denervated lateral rectus muscle.
Pseudostrabismus is the false appearance of
strabismus. It generally occurs in infants and toddlers whose
bridge of their nose is wide and flat. This causes the
appearance of strabismus. With age the bridge of the child's
nose will narrow and the folds in the corner of the eyes will go
away. To detect the difference between pseudostrabismus and
strabismus use a flashlight and shine it in the child's eyes.
When the child is looking at the light a reflection can be seen
on the front surface of the pupil. If the eyes are properly
aligned with one another then the reflection will be in the same
spot of each eye. If strabismus is present, then the reflection
from the light will not be in the same spot of each eye.
Treatment and Management
As with other binocular vision disorders, the
primary therapeutic goal for those with strabismus is
comfortable, single, clear, normal binocular vision at all
distances and directions of gaze.
If minor and detected early, strabismus can
often be corrected with enforced use of an eyepatch on the
dominant eye and/or vision therapy. Advanced strabismus is
usually treated with a combination of eyeglasses or prisms,
vision therapy, and surgery, depending on the underlying reason
for the misalignment. Surgery attempts to align the eyes by
shortening, lengthening, or changing the position of one or more
of the extraocular eye muscles, and is frequently the only way
to achieve cosmetic improvement. Glasses affect the position by
changing the person's reaction to focusing. Prisms change the
way light, and therefore images, strike the eye, simulating a
change in the eye position.
Early treatment of strabismus in infancy can reduce the
chance of developing amblyopia and depth perception problems.
Eyes that remain misaligned can still develop visual problems.
Although not a cure for strabismus, prism lenses can also be
used to provide some comfort for sufferers and to prevent double
vision from occurring.
In adults with previously normal alignment, the onset of
strabismus usually results in double vision (diplopia).
Associated Retinal Consultants P.C. provides this on-line information
for educational and communication purposes only and it should not be construed
as personal medical advice. Information published on this website is not
intended to replace, supplant, or augment a consultation with an eye care
professional regarding the viewer/user's own medical care.
Associated Retinal Consultants P.C.
disclaims any and all liability for injury or other damages that could result
from use of the information obtained from this site. |
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