Investigative ophthalmology & visual science
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Eye movements that accompany a blink have been measured in human subjects by the use of a visual-persistence method. With straight-ahead binocular viewing, each eye typically rotates nasalward and downward 1-2 deg during the closing phase of a blink. These eye movements are more rapid than the lid movements as recorded by high-speed photography. ⋯ Sequential photography of the cornea in profile reveals that the eye moves inward and back out again during a blink. The amplitude of this retraction is typically less than 1 mm; and its time course, slower than that of the rotational eye movements, parallels the closure and opening of the lids. In normal conditions of viewing there is no evidence of conjugate saccades, or of any large, upward rotation of the eyes (Bell's phenomenon) that was once believed to take place during a blink.