This scanning electron micrograph showing part of the iris, the area of the eye around the central pupil, is magnified 170 times and has been coloured to reveal the structures more clearly. The iris is made of smooth muscle. It controls the size of the pupil (far right, blue), and therefore how much light enters the eye. The band of folds (red) around the inner edge is where the filaments (yellow and green) that suspend the lens are attached. If you look closely at your eye in the mirror, you will see the radiating pattern that is shown in detail here.