How does the eye adjust itself to deal with light of varying intensity?
To deal with light of varying intensity the eye adjust itself by the help of the iris. The iris adjust the pupil automatically according to the intensity of light received by the eye. If the intensity of light is large, then iris contracts the pupil and reduces the amount of light entering the eye. And, if the intensity of light is small, then iris expands the pupil so that more light may enter the eyes.