https://www.youtube.com/watch?v=0 rbCrJoTatE Link to good cow eye dissection video
The Eye - pupil The pupil is a circular hole in the iris. The black colour comes from a layer in the eye that stops internal reflections. In bright light the iris reduces the size of the pupil. In dim light the pupil is large.
The Eye - cornea The cornea is a layer of transparent skin on the front of the eye. It plays an important part in focussing the light (along with the lens)
The eye - retina The retina is a light sensitive layer at the back of the eye that sends messages to the brain via the optic nerve
The eye - lens The lens can change shape to focus both near and far objects