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periphoria(per-i-fo're-a) [? + phoros, bearing]
The tendency of the axis of the eye to deviate from the normal owing to weakness of extraocular muscles. Synonym: cyclophoria
When binocular vision is dissociated (i.e. when stimuli to fusion are eliminated) one eye or both rotate about its/their respective anteroposterior axes to take up the passive position. If the upper portion of the eye rotates inward, it is called incyclophoria and if it rotates outward, it is called excyclophoria. It is usually caused by an anomaly of the oblique muscles. Cyclophoria is commonly associated with hyperphoria. There are various methods which can be used to detect cyclophoria: the Maddox rod test; the double prism test; the synoptophore with appropriate slides; the fixation disparity unit; Fresnel's bi-prism. Syn. periphoria. See cyclotropia; double prism test; Maddox rod test.