The term "enters" refers to the action of something going into or coming inside a specific place or object.
Iris: The iris is a ring-shaped muscle in our eyes that controls the size of our pupils, thereby regulating the amount of light entering the eye.
The pupil is an opening in the center of our iris that allows light to enter our eyes. It adjusts its size based on lighting conditions.
The lens is a transparent structure located behind the iris and it helps focus incoming light onto our retina.