strabismus
stra·bis·mus
S0788000 (strə-bĭz′məs)strabismus
(strəˈbɪzməs) orstrabism
stra•bis•mus
(strəˈbɪz məs)n.
strabismus
| Noun | 1. |  strabismus - abnormal alignment of one or both eyes |
n.
strabismus
strabismus
(strəbĭz`məs), inability of the eyes to focus together because of an imbalance in the muscles that control eyeeye,organ of vision and light perception. In humans the eye is of the camera type, with an iris diaphragm and variable focusing, or accommodation. Other types of eye are the simple eye, found in many invertebrates, and the compound eye, found in insects and many other
..... Click the link for more information. movement; also called squint. It is a consequence of weakness or uneven development of one or more of the six small muscles that surround the eye. One or both eyes may be affected. Horizontal strabismus is caused when the eyes do not move together laterally; this condition is known as cross-eye if the eye turns inward or walleye if the eye turns outward. Vertical strabismus results when the eye rolls upward or downward in its socket. There is also torsional strabismus in which the eyes do not rotate together about their optical axes. Strabismus is usually present at birth and becomes apparent early in infancy, but it may also result from illness or injury. Because the condition results in perception of a double image, there is a tendency to use only one eye. It is important that treatment be started as soon as possible to prevent loss of sight in the unused eye. Corrective therapy includes exercise that strengthens eye muscles and prescription of corrective lenses. Sometimes a patch is placed alternately on each eye so that neither is allowed to become completely unused. If necessary, the eye muscles may be shortened or lengthened surgically.
Strabismus
deviation of the visual axis of one of the eyes from the common point of fixation, leading to a loss of binocular vision. Two types are distinguished: concomitant and paralytic strabismus.
Concomitant strabismus, in which the deviating eye always follows the movement of the other eye and the angle of divergence of their visual axes remains constant, is observed predominantly in children (up to 2 percent). Its causes have not been conclusively elucidated. Strabismus may be accommodative, owing to anomalies of refraction and disturbances of eye accommodation, or nonaccommodative. Accommodative strabismus disappears upon administration of drops of atropine in the eye and use of corrective lenses: nonaccommodative strabismus is distinguished by extreme persistence. Strabismus may be constant or periodic, unilateral (when only one eye deviates) or alternating, and convergent (when the deviating eye moves toward the nose) or divergent (when the deviating eye moves toward the temple); the eye may simultaneously deviate upward or downward as well.
In approximately half the cases of concomitant strabismus some decrease in acuity of vision is noted in the deviating eye. The treatment of nonaccommodative strabismus is manifold, employing both various exercises for the eyes on special instruments (synoptophores, amblyoscopes) and operations directed toward weakening the stronger eye muscle or strengthening its antagonist.
Paralytic strabismus originates with paralysis of the oculomotor muscles as a result of disease of the central nervous system (infection, hemorrhage). It is characterized by limited mobility of the paralyzed eye, double images, and a different deflection angle of either eye. Treatment is directed at the disease causing the strabismus; sometimes vision can be restored by special operations on the eye muscles.
REFERENCE
Mnogotomnoe rukovodstvo po glaznym bolezniam, vol. 3, book 1. Moscow, 1962. Pages 237–355.M. L. KRASNOV
strabismus
[strə′biz·məs]strabismus
strabismus
Strabismus
Definition
Description
- inward (esotropia or "crossed eyes")
- outward (exotropia or "wall eyes")
- upward (hypertropia)
- downward (hypotropia)
Types of strabismus
False strabismus (pseudostrabismus)
- extra skin that covers the inner corner of the eye
- a broad, flat nose
- eyes set unusually close together or far apart
Causes and symptoms
- brain tumors
- cerebral palsy
- Down syndrome
- hydrocephalus
- other disorders that affect the brain
- diabetes
- head trauma
- stroke
- brain tumor
- other diseases affecting nerves that control eye muscles
Diagnosis
Treatment
- glasses to aid in focusing and straighten the eye(s)
- patching to force infants and young children to use and straighten the weaker eye
- eye drops or ointments as a substitute for patching or glasses, or to make glasses more effective
- surgery to tighten, relax, or reposition eye muscles
- medication injected into an overactive eye muscle to allow the opposite muscle to straighten the eye
- vision training (also called eye exercises)
Prognosis
Resources
Organizations
strabismus
[strah-biz´mus]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.
stra·bis·mus
(stra-biz'mŭs), [MIM*185100]strabismus
(strə-bĭz′məs)strabismus
Nonparallel positioning or movement of the eyes—usually of the vertical axis—due to decreased binocular muscle coordination with loss of stereoscopic vision and inability to focus simultaneously on a single point.Aetiology
Extraocular muscle defects, neurotoxins, blindness, mechanical defects, unilateral vision obstruction in childhood, various brain disorders or systemic diseases, amblyopia, paralytic shellfish poisoning, botulism, haemangioma near eye, Guillain-Barré syndrome, Apert syndrome, Noonan syndrome, Prader-Willi syndrome, trisomy 18, congenital rubella, incontinentia pigmenti, cerebral palsy, Laurence-Moon-Biedl syndrome, pseudohyperparathyroidism.
strabismus
Crossed eyes; exotropia, walleye Ophthalmology Nonparallel position or movement of eyes, due to ↓ muscle coordination between eyes, with loss of stereoscopic vision and inability to focus simultaneously on a single point Etiology Extraocular muscle defects, neurotoxins, blindness, mechanical defects, unilateral vision obstruction in childhood, various brain disorders or systemic diseases, amblyopia, paralytic shellfish poisoning, botulism, hemangioma near eye, Guillain-Barre´ syndrome, Apert syndrome, Noonan syndrome, Prader-Willi syndrome, trisomy 18, congenital rubella, incontinentia pigmenti, cerebral palsy, Laurence-Moon-Biedl syndrome, pseudohyperparathyroidism. See Farsightedness, Myopia.stra·bis·mus
(stră-biz'mŭs)Synonym(s): crossed eyes, cross-eye, heterotropia, heterotropy, squint (1) .
strabismus
Squint. The condition in which only one eye is aligned on the object of interest. The other eye may be directed too far inward (convergent strabismus), too far outward (divergent squint), or upward or downward (vertical squint). Squint in childhood, or any squint of recent onset, requires urgent treatment. Untreated childhood squint often leads to AMBLYOPIA. New squints in adults usually imply a disorder of the nervous system.strabismus
accommodative strabismus Convergent strabismus resulting from abnormal demand on accommodation due to an uncorrected hyperopia accompanied by excessive convergence and insufficient relative fusional divergence. The AC/A ratio (accommodative convergence to accommodation) is normal but the child has high hyperopia (refractive accommodative esotropia). It may also occur in cases in which the AC/A ratio is high and accommodation is accompanied by excessive convergence in a child with a very small amount of hyperopia (non-refractive accommodative esotropia). Accommodative strabismus is usually an acquired deviation first presenting in the first decade of life. Children do not usually notice diplopia, but instead develop suppression and later amblyopia. Management consists of full hyperopic correction and amblyopia treatment. Syn. accommodative esotropia. See cycloplegic refraction; acquired non-accommodative strabismus.
acquired strabismus An abnormal alignment of the visual axes that occurs after the age of six months.
acquired non-accommodative strabismus Convergent strabismus that presents after normal ocular alignment has been established and is not related to a subject's accommodative effort. Treatment is usually surgical. Syn. acquired non-accommodative esotropia.
alternating strabismus Strabismus in which either eye may deviate. See unilateral strabismus.
angle of strabismus See angle of deviation.
apparent strabismus Condition simulating the appearance of strabismus. It may be due to epicanthus, to an abnormally large angle lambda (or kappa), or to the breadth of the nose, etc. It can be distinguished from a real strabismus by noting that the corneal light reflexes are centrally located in relation to the pupils, or by means of the cover test. Syn. pseudostrabismus.
comitant strabismus See concomitant strabismus.
concomitant strabismus Strabismus in which the angle of deviation remains the same whichever eye is fixating and in whichever direction the eyes are looking. Syn. comitant strabismus. See concomitance; incomitant strabismus.
congenital strabismus See infantile strabismus.
consecutive strabismus A deviation of the eye in the opposite direction to what it was previously. This condition may follow surgery although it may occur spontaneously. There are two types: consecutive exotropia in a patient who previously had esotropia or esophoria and consecutive esotropia in a patient who previously had exotropia or exophoria. Syn. postoperative over-correction. See divergent strabismus.
convergent strabismus Strabismus in which the deviating eye turns inward. This is the most common type of strabismus in children. The principal categories are accommodative strabismus and non-accommodative strabismus (Fig. S15). Syn. crossed eyes (colloquial); esotropia (SOT, ET, esoT). See A pattern; V pattern; Swann's syndrome; prism adaptation test.
cyclic strabismus A very rare and unusual form of strabismus occurring on a 48-hour rhythm in which a 24-hour period of normal binocular vision is followed by 24 hours of manifest heterotropia. The condition, which may have started in early infancy, only becomes apparent during early childhood. With time, cyclic heterotropia tends to become constant. Syn. cyclic heterotropia.
deorsumvergens strabismus See hypertropia.
divergent strabismus Strabismus in which the deviating eye turns outward (Fig. S15). Syn. exotropia (XOT; XT; exoT). The principal categories are constant exotropia and intermittent exotropia. Constant exotropia may be congenital which is often associated with an underlying neurological anomaly or basic which appears after six months of age with equal exotropia for near and distance vision. Both types are usually treated surgically. Consecutive strabismus can also be a constant exotropia. Intermittent exotropia is the most common form of exotropia. It begins as an exophoria and breaks down to exotropia presenting in children between two and five years of age. It is characterized by worse exotropia at near (convergence excess) or worse exotropia at distance (divergence excess). Treatment includes spectacle correction, orthoptic exercises or surgery. See A pattern; V pattern.
strabismus fixus A rare, congenital condition in which one or both eyes are firmly fixed in a position of extreme adduction or abduction, although the most common position is adduction (esotropia). It is due to an anatomical anomaly (e.g. anomalous insertion of the medial or lateral rectus muscle), or muscle fibrosis (e.g. of the two medial recti muscle in esotropia). Voluntary movements of duction and version, as well as passive movements as in the forced duction test, are either absent or insignificant. See forced duction test.
incomitant strabismus Strabismus in which the angle of deviation varies with the direction of gaze and with the eye used for fixation. It may be congenital or acquired. The congenital type is due to some developmental anomaly of one or more of the extraocular muscles or of the neural component that serves them. The acquired type may be due to head injury, disease of the oculomotor system, or systemic disease (e.g. multiple sclerosis, myasthenia gravis, thyroid eye disease, aneurysms). The main symptom of incomitant strabismus is diplopia and it suddenly appears in the acquired type. Abnormal head posture and past-pointing may be present. The affected muscle(s) may be detected by the motility test. Treatment is aimed first at the primary cause but, in general, this type of strabismus does not respond well to orthoptic procedures. In large deviation, surgery is usually the only remedy. Syn. nonconcomitant strabismus. See abnormal head posture; incomitance; pointing past-; Hess screen; paralytic strabismus; motility test.
infantile strabismus Strabismus which becomes manifest within the first year of life. It is almost always esotropic in nature: exotropia, which is very rare, is usually associated with some neurological condition. Infantile strabismus is characterized by a large angle of squint, hyperopia, alternate fixation that may become unilateral if amblyopia develops, and nystagmus. Management is essentially surgical after correction of the refractive error. A complication following surgery may be dissociated vertical deviation. Syn. congenital strabismus; infantile esotropia syndrome. See cross-fixation.
intermittent strabismus Strabismus that is not present at all times.
monocular strabismus See unilateral strabismus.
non-accommodative strabismus Convergent strabismus not due to abnormal demands on accommodation. There are several types: infantile strabismus, acquired non-accommodative strabismus, basic esotropia (no significant hyperopia and the deviation is equal for near and distance), microtropia, convergence excess (esotropia for near vision but not for distance), divergence insufficiency (esotropia for distance vision but not for near), consecutive strabismus, sensory strabismus and cyclic esotropia (periodic manifestation of esotropia as for example on alternate days). Treatment of associated amblyopia and correction of hyperopia are often followed by surgery.
nonconcomitant strabismus See incomitant strabismus.
paralytic strabismus Strabismus due to a paralysis of the extraocular muscles. It usually gives rise to incomitance. The paralysis is usually due to a disorder of the third, fourth or sixth cranial nerve. Diplopia is noticed if the paralysis is recent and it is usually accompanied by an abnormal head posture. In most cases there is not a complete loss of action of a muscle but a partial loss and the condition is referred to as paretic strabismus, whether it is congenital or acquired. Orthoptic treatment is very limited in these cases and is not normally appropriate if the deviation was caused by injury or a recent disease. Cosmetic surgery is often necessary. See abnormal head posture; incomitance; paralysis of the fourth nerve; paralysis of the sixth nerve; paralysis of the third nerve; motility test.
periodic strabismus Strabismus in which the deviation occurs only at certain distances or in certain directions of fixation. Syn. relative strabismus.
relative strabismus See periodic strabismus.
secondary s . Strabismus resulting from a sensory deficit, surgical intervention, tumour, trauma or stroke. See consecutive strabismus; sensory strabismus.
sensory strabismus Strabismus caused by a unilateral reduction in visual acuity which disrupts binocular vision, such as unilateral cataract, optic atrophy, uncorrected anisometropia or other unilateral visual impairments.
small angle strabismus See microtropia.
strabismus surgery See myectomy; myotomy; Faden procedure; tuck procedure; recession; resection; transposition.
sursumvergens strabismus See hypertropia.
unilateral strabismus Strabismus in which the deviating eye is always the same, as distinguished from alternating strabismus. Syn. monocular strabismus.
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stra·bis·mus
(stră-biz'mŭs) [MIM*185100]Synonym(s): crossed eyes, heterotropia, squint (1) .
strabismus
- noun
Synonyms for strabismus
noun the condition of not having the visual axes parallel
Synonyms
- cross-eye
- squint
Synonyms for strabismus
noun abnormal alignment of one or both eyes
Synonyms
- squint
Related Words
- abnormalcy
- abnormality
- convergent strabismus
- crossed eye
- cross-eye
- esotropia
- divergent strabismus
- exotropia
- walleye
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- schedule d
- scheduled
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