Circular muscles surrounding the pupil, it can have lighter colors in the iris do to lack of melanin or pigment which gives the body, hair, and eyes there color. Help regulate the amount of light entering the eye
a layer at the back of the eyeball containing cells that are sensitive to light and that trigger nerve impulses that pass via the optic nerve to the brain, where a visual image is formed.
a small depression in the retina of the eye where visual acuity is highest. The center of the field of vision is focused in this region, where retinal cones are particularly concentrated.