Many people choose to compare the eye to a camera, and in a way this is a good comparison. Like a camera, the eye is able to refract light and produce a focused image that can stimulate neural responses and enable the ability to see. There are many anatomical aspects of the eye which make vision possible. Listed below are the different parts of the human eye and their function (All vocabulary adapted from Land, M. F.,2006). The ultimate goal of all these parts of the eye is to work together in a fashion to focus images on the back of the retina and allow vision to occur. The feline eye, in essence, uses all these same parts in order to create vision. However, there are some distinct differences to be noted.
Diagram image courtesy of www.friendskorner.com
Cornea: A transparent surface which covers the eye. The cornea is a thin membrane which helps to protect the eye as well as to allow light to enter the eye.
Pupil: The black aperture in the center of the eye. Its black appearance is attributed to the fact that the light which the pupil allows to enter from the cornea is absorbed on the retina (and elsewhere) and does not exit the eye.
Iris: The colored part of the eye which surrounds the pupil. It is a circular muscle which is diaphragm-like in its ability to stretch and reduce the size of the opening of the pupil. In bright-light situations, the iris adjusts its size to reduce the pupil opening and limit the amount of light which enters the eye. And in dim-light situations, the iris adjusts so as to maximize the size of the pupil opening and increase the amount of light which enters the eye.
Sclera: The white of the eye, which forms part of the supporting wall of the eyeball and is a part of the cornea and central nervous system.
Retina: The inner surface of the eye that contains the rods and cones which serve the task of detecting the intensity and the frequency of the incoming light. These rods and cones send nerve impulses to the brain. The nerve impulses travel through a network of nerve cells known as the Optic Nerve.
Rods: Responsible for vision at low levels of light. They do not mediate color vision.
Cones: Responsible for vision at higher levels of light, as well as color in vision.
Questions or Comments? Please e-mail me at email@example.com