heterophoria

A tendency for deviation of the eyes from parallelism, prevented by binocular vision. [hetero- + G. phora, movement]

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het·ero·pho·ria .het-ə-rō-'fōr-ē-ə, -'fȯr-ē-ə n latent strabismus in which one eye tends to deviate either medially or laterally compare EXOPHORIA

het·ero·phor·ic -'fȯr-ik, -'fär-ik adj

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n.

a tendency to squint. Under normal circumstances both the eyes work together and look at the same point simultaneously, but if one eye is covered it will move out of alignment with the object the other eye is still viewing. When the cover is removed the eye immediately returns to its normal position. Most people have some small degree of the type of heterophoria known as exophoria, in which the covered eye turns outwards, away from the nose (compare esophoria). Heterophoria often produces eyestrain because of the unconscious effort required to keep the two eyes aligned. See also strabismus.

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het·ero·pho·ria (het″ər-o-forґe-ə) [hetero- + Gr. phora movement, range] failure of the visual axes to remain parallel after the visual fusional stimuli have been eliminated. Types are named using the suffix phoria with a prefix indicating the direction of deviation. See cyclophoria, esophoria, exophoria, hyperphoria, and hypophoria. Called also latent deviation.