When referring to lenses, what does the term "extorsion" mean in relation to movement?

• A. A movement to turn the eye outward
• B. A movement to turn the eye inward
• C. A movement to raise the eye
• D. A movement to lower the eye

Answer: (A)

The term "extorsion" in relation to eye movement refers specifically to the rotation of the eye around the visual axis, causing the top of the eye to rotate outward. When the eye undergoes extorsion, it effectively turns away from the midline of the body, which is consistent with the description of a movement that turns the eye outward.

This term is important in the context of ocular motility and lens prescription, as it relates to how the eyes align and the effects various conditions and lens types can have on eye movement. Understanding extorsion can help optometric technicians assess a patient's eye movement and any associated challenges they may face with balance, coordination, or other visual tasks.

The other options describe movements associated with different terms; for instance, a movement to turn the eye inward is termed "intorsion," raising the eye involves "elevation," and lowering the eye refers to "depression." Each of these terms has distinct meanings and implications in the study of eye movements and is not synonymous with extorsion.