divergent strabismus


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Related to divergent strabismus: convergent strabismus

strabismus

 [strah-biz´mus]
deviation of the eye that the patient cannot overcome; the visual axes assume a position relative to each other different from that required by the physiological conditions. Called also squint. adj., adj strabis´mic. The various forms of strabismus are spoken of as tropias, their direction being indicated by the appropriate prefix, as cyclotropia, esotropia, exotropia, hypertropia, and hypotropia.

During the first 3 to 6 months of life, the eyes of infants tend to waver and turn either inward or outward independently of one another; this usually corrects itself. If it persists, or if the eyes are continually crossed in the same way, even if the child is less than 6 months old, it may be a sign of strabismus. Children do not outgrow strabismus. In an older child, a tendency to tilt the head when reading, or to close or rub one eye, may indicate strabismus.

Strabismus almost always appears at an early age. If not corrected, the condition may impair vision in the nonfocusing eye, as well as marring the child's appearance. In the great majority of cases the eyes can be straightened by proper medical treatment at any age, but vision of the malfunctioning eye may remain impaired. If treated early enough, preferably before 6 years, normal vision can usually be restored in the affected eye.
Cause. Strabismus may result from several factors, including a blow on the head, disease, or heredity. Many cases are caused by a malfunction of the muscles that move the eyes. This causes the eyes to focus differently, sending different images to the brain. As the child grows, he or she learns to ignore the image from one eye with the result that it fails to grow as strong as the eye on which he or she is depending.
Treatment. Treatment for strabismus varies with the individual case. A patch may be placed over the child's stronger eye for a period, forcing use of the weaker eye and thus restoring its strength as far as possible, instead of letting it grow worse from lack of use. Eyeglasses or special eye exercises may correct the condition. In some cases, a relatively simple surgical operation on the eye muscles may be necessary. Since these muscles are outside the eye itself, there is no danger to the vision.
comitant strabismus (concomitant strabismus) that in which the angle of deviation of the visual axis of the squinting eye is always the same in relation to the other eye, no matter what the direction of the gaze; due to faulty insertion of the eye muscles.
convergent strabismus esotropia.
divergent strabismus exotropia.
noncomitant strabismus (nonconcomitant strabismus) that in which the amount of deviation of the squinting eye varies according to the direction in which the eyes are turned.
vertical strabismus that in which the visual axis of the squinting eye deviates in the vertical plane; see hypertropia and hypotropia.

ex·o·tro·pi·a

(ek'sō-trō'pē-ă),
That type of strabismus in which the visual axes diverge; may be paralytic or concomitant, monocular or alternating, constant or intermittent.
[exo- + G. tropē, turn]

divergent strabismus

See exotropia.

ex·o·tro·pi·a

(ek'sō-trō'pē-ă)
That type of strabismus in which the visual axes diverge; may be paralytic or concomitant, monocular or alternating, constant or intermittent.
Synonym(s): divergent strabismus, exodeviation (2) , wall-eye.
[exo- + G. tropē, turn]

strabismus

deviation of the eye that the patient cannot overcome; the visual axes assume a position relative to each other different from that required by the physiological conditions. Called also squint.
Enlarge picture
Basic types of strabismus. By permission from Guyton R, Hall JE, Textbook of Medical Physiology, Saunders, 2000

comitant strabismus
extraocular muscles are not paralyzed and the degree of deviation is the same in all directions.
congenital strabismus
medial strabismus is seen in Siamese cats. See convergent strabismus (below).
convergent strabismus
that in which the visual axes converge; esotropia, or cross-eye. A frequent finding in Siamese cats, related to an anomaly of neuronal pathways between the retina and lateral geniculate nucleus in which more neurons project contralaterally rather than ipsilaterally as in other cats.
divergent strabismus
that in which the visual axes diverge; called also exotropia and walleye.
inherited strabismus
see inherited exophthalmos.
noncomitant strabismus
deviation due to paralysis of one or more muscles.
traumatic strabismus
a complication of traumatic prolapse of the eye, due to rupture of extraocular muscles.