What does anisocoria describe?

Anisocoria specifically refers to a condition in which there is a difference in the sizes of the pupils of the eyes. This can occur due to various physiological or pathological reasons, including neurological conditions, eye trauma, or the effects of certain medications. The condition can be benign or may indicate a more serious underlying issue, so it is often evaluated during an eye examination.

The other options do not correctly define anisocoria. A difference in refractive power relates to how well light is bent for focusing and is not directly connected to pupil size. Inward turning of the eye refers to strabismus or esotropia, which involves the eye's misalignment rather than pupil size variance. Symptoms of eye strain encompass a range of discomforts such as headaches or blurry vision, but they do not specifically relate to differences in pupil sizes. Thus, the focus on the measurement of pupil size differences clearly identifies the correct definition of anisocoria.