Although it is small in size, the eye arguably provides us with the most important of the five senses - vision. The retina, which is made up by millions of specialised cells known as rods and cones , transforms the image into electrical energy and this is sent to the optic disk on the retina where it will be transferred via electrical impulses along the optic nerve to be processed by the brain. Please click on the labels for more detailed definitions. The iris regulates the amount of light that enters the eye. It forms a coloured muscular diaphragm across the front of the lens .
Light enters through a central opening called the pupil .
The circular opening in the centre of the iris through which light passes into the lens of the eye. The iris controls dilation and constriction of the pupil. The transparent circular part of the front of the eyeball. It refracts the light entering the eye onto the lens , which then focuses it onto the retina . The cornea contains no blood vessels and is extremely sensitive to pain.