In ocular motility testing, which statement correctly contrasts ductions with versions?

In ocular motility testing, which statement correctly contrasts ductions with versions?

• A. Ductions are binocular movements; versions are monocular.
• B. Ductions are conjugate movements of both eyes; versions are eye movements of one eye.
• C. Ductions are monocular eye movements; versions are binocular conjugate movements.
• D. Ductions test color vision.

Answer: (C)

The important idea is that ductions assess movement of a single eye in isolation, while versions assess coordinated movement of both eyes in the same direction. Ductions are tested monocularly (the other eye is occluded) to isolate that one eye’s muscles, whereas versions involve both eyes moving together (conjugate, binocular movement). Therefore, ductions are monocular eye movements and versions are binocular conjugate movements. The other statements don’t fit because they misstate how many eyes are moving or what is being tested (ductions aren’t color vision tests, and versions aren’t limited to one eye).

The important idea is that ductions assess movement of a single eye in isolation, while versions assess coordinated movement of both eyes in the same direction. Ductions are tested monocularly (the other eye is occluded) to isolate that one eye’s muscles, whereas versions involve both eyes moving together (conjugate, binocular movement). Therefore, ductions are monocular eye movements and versions are binocular conjugate movements. The other statements don’t fit because they misstate how many eyes are moving or what is being tested (ductions aren’t color vision tests, and versions aren’t limited to one eye).