Eyes are made up of a number of different parts, each of which has a different function, and all of which are important for sight.
Vitreous Gel: The clear jelly-like substance that fills the inside of the eye from the lens to the retina.
Cornea: The transparent protective outer layer that covers the front of the eyeball and also helps to focus light.
Pupil: The hole in the centre of the iris, which is visible as a black circle.
Lens: A transparent body that bends and focuses light rays onto the retina.
Iris: The coloured part of the eye – a blue or brown or green circle surrounding the pupil. The iris can control the amount of light that enters the eye by changing the size of the pupil.
Optic Nerve: This is a bundle of nerves which transmit the images focused on the retina to the brain.
Macula: This small area in the centre of the retina is responsible for what is seen directly in front of someone, at the centre of the field of vision. The macula is very important because it is responsible for the vision needed to carry out detailed activities such as reading or recognising faces. Whilst the entire retina allows sight of a book, it is the macula which gives the ability to read the words and see the pictures properly.
Retina: The light sensitive inner lining at the back of the eye which acts like the film in a camera. When rays of light enter the eye they are focused on the retina by the cornea and the lens. The retina contains millions of special cells that pick up the light and convert it into nerve signals. These signals are then sent along the optic nerve for the brain to interpret and this becomes ‘sight’.
Other parts of the eye, not shown on the diagram above, are:
Sclera: The white of the eye and the protective outer coating of the eyeball.
Tear Film: The liquid layer that covers and protects the outer surfaces at the front of the eye.