This refers to the change of tissue to a lower or less functionally active form, of the thin, circular structure in the eye, responsible for controlling the diameter and size of the pupil and thus the amount of light reaching the retina. The color of the iris is often referred to as "eye color."
Also indexed as
Acute bilateral depigmentation of irisDegeneration of irisPigmentary degeneration of irisTranslucency of iris