Iris

Iris - The iris is the coloured part of the choroid membrane. The amounts of pigment in iris decide if we have blue- or brown eyes. Iris is front of the lens and contains of 2 muscles One is closing and the other open the pupil. The pupil is the hole in the middle of iris. The pupil works like the aperture in the camera.

When the eye is exposed to strong light, a reflex is released which makes the irises' muscles close and the pupil will have a smaller size to protect the eye against to much light.