(I-ris) 
The colored tissue at the front of the eye that contains the pupil in the center. The iris helps control the size of the pupil to let more or less light into the eye.
Figure
Anatomy of the eye, showing the outside and inside of the eye including the eyelid, pupil, sclera, iris, cornea, lens, ciliary body, retina, choroid, vitreous humor, and optic nerve.