version
Also called versions, conjugate eye movement, conjugate gaze, binocular conjugate movement
A movement in which both eyes turn in the same direction, so that the angle between them stays constant. Gaze to the right and left are dextroversion and levoversion, gaze up and down are supraversion and infraversion, and the cycloversions roll both eyes the same way when the head tilts1,2. Versions are fast movements driven by equal and simultaneous nerve signals to the yoke muscles, the pair, one in each eye, that move the eyes the same way (Hering's law)1.
A version differs from a vergence, in which the eyes move in opposite directions and which is slow, and from a duction, the movement of one eye alone while the other is covered1. Versions are examined with a penlight moved through the nine diagnostic positions of gaze with both eyes open.
More detail
The oblique versions reach the corner positions of gaze. Versions reveal a mild paresis that ductions can hide: when the weak eye fixates it drives its weak muscle harder, and the same extra signal reaches the yoke muscle of the fellow eye, which overacts and shows the deviation1.
Sources (2)
- von Noorden and Campos, Binocular Vision and Ocular Motility, ch. 4
- Kanski, Clinical Ophthalmology (2024), ch. 18
Reviewed October 2026