- Both pupils are usually of equal size. If they are not, that is termed anisocoria (from "a-", not + "iso", equal + "kore", pupil = not equal pupils).The pupil may appear to open (dilate) and close (constrict) but it is really the iris that is the prime mover; the pupil is merely the absence of iris. The size of the pupil determines how much light is let into the eye. With anisocoria, the larger pupil lets more light enter the eye.
* * *- simple a. a common (20% of normals) benign inequality of the pupils that may change from one hour to the next. SYN: essential a., physiologic a., simple-central a..- simple-central a. SYN: simple a..
* * *an·iso·co·ria .an-.ī-sō-'kōr-ē-ə n inequality in the size of the pupils of the eyes
* * *n.inequality in the size of the pupils of the two eyes, usually a difference of more than 1 mm in diameter.
* * *an·iso·co·ria (an-i″so-korґe-ə) [aniso- + cor- + -ia] inequality in diameter of the pupils.
Anisocoria; iris heterochromia is also present.
Medical dictionary. 2011.