Strabismus | |
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Other names | Heterotropia, crossed eyes, squint[1] |
A person with exotropia, an outward deviated eye | |
Pronunciation | |
Specialty | Ophthalmology, optometry |
Symptoms | Nonaligned eyes[2] |
Complications | Amblyopia, double vision[3] |
Types | Esotropia (eyes crossed); exotropia (eyes diverge); hypertropia (eyes vertically misaligned)[3] |
Causes | Muscle dysfunction, farsightedness, problems in the brain, trauma, infections[3] |
Risk factors | Premature birth, cerebral palsy, family history[3] |
Diagnostic method | Observing light reflected from the pupil[3] |
Differential diagnosis | Cranial nerve disease,[3] convergence insufficiency |
Treatment | Glasses, surgery[3] |
Frequency | ~2% (children)[3] |
Strabismus is a vision disorder in which the eyes do not properly align with each other when looking at an object.[2] The eye that is pointed at an object can alternate.[3] The condition may be present occasionally or constantly.[3] If present during a large part of childhood, it may result in amblyopia, or lazy eyes, and loss of depth perception.[3] If onset is during adulthood, it is more likely to result in double vision.[3]
Strabismus can occur due to muscle dysfunction (e.g., myasthenia gravis[4][5]), farsightedness, problems in the brain, trauma, or infections.[3] Risk factors include premature birth, cerebral palsy, and a family history of the condition.[3] Types include esotropia, where the eyes are crossed ("cross eyed"); exotropia, where the eyes diverge ("lazy eyed" or "wall eyed"); and hypertropia or hypotropia where they are vertically misaligned.[3] They can also be classified by whether the problem is present in all directions a person looks (comitant) or varies by direction (incomitant).[3] Diagnosis may be made by observing the light reflecting from the person's eyes and finding that it is not centered on the pupil.[3] This is known as the Hirschberg reflex. Another condition that produces similar symptoms is a cranial nerve disease.[3]
Treatment depends on the type of strabismus and the underlying cause.[3] This may include the use of glasses and possibly surgery.[3] Some types benefit from early surgery.[3] Strabismus occurs in about 2% of children.[3] The term comes from the Ancient Greek word στραβισμός (strabismós), meaning 'a squinting'.[6] Other terms for the condition include "squint" and "cast of the eye".[7][8][9]