The Eye

Your eyes are marvellous instruments and are made up of the following parts:

Lens - a transparent body behind the iris, the coloured part of the eye. The lens bends light rays so that they form a clear image at the back of the eye – on the retina. The lens can change shape, as it is elastic, getting fatter to focus close objects and thinner for distant objects.

Cornea - the transparent membrane which forms the outer coating at the front of the eyeball and covers the iris and pupil. It also focuses light on the retina.

Pupil - the dark circular hole in the centre of the iris.

Iris - The iris is the coloured circle surrounding the pupil. It changes the size of the pupil and allows different amounts of light to enter the eye.

Retina - The retina is the light-sensitive inner lining of the back of the eye. Imagine that the eye is like a camera, and the retina is the film. Rays of light enter the eye and are focused on the retina by the cornea and lens. The retina produces an image which is sent along the optic nerve for the brain to interpret, rather like developing a camera film.

Macula - the small area at the centre of the retina at the centre of our field of vision. It is responsible for what we see straight in front of us and is very important as it gives us the vision needed for detailed activities such as reading and writing, and the ability to appreciate colour.

Sclera - the white of the eye and forms the outer coating of the eyeball.

Conjunctiva - a mucous membrane that covers the exposed front portion of the sclera and lines the inside of the eyelids.

Tear film - the moist layer that covers and protects the outer surfaces at the front of the eye.

Vitreous - the clear, jelly-like substance that fills the inside of the eye from the lens to the retina.

More information can be found on the following websites:

NHS Direct
College of Optometrists
RNIB