Functions of the iris of the eye.

The iris of the eye has a very complex structure and important function. It tends to expand or contract. We say “dilated pupil” or “constricted pupil”. This is due to the iris. This property is necessary to regulate the amount of light that hits the retina. On a sunny day, we can notice that our pupil is small, but at night the pupils are maximally dilated. The color of the iris depends on the amount of pigment in the body. In children and the elderly, there is not enough pigment and the iris has a weak color.