Iris is part of the Uvea, which is a four-letter word. Iris is the colored part of the eye that surrounds the pupil and controls the amount of light entering the eye. It is made up of two layers, the stroma and the pigmented epithelium. The stroma is composed of connective tissue and smooth muscle fibers, while the pigmented epithelium contains melanin granules that give the iris its color. The size and shape of the iris determine the eye color.