The eye functions like a camera. When you look at an object, light enters through the cornea and starts to be focussed. The light travels through the pupil and is focussed further by the lens. To achieve good vision the light must come to a clear focus on the retina. From the retina this information is then taken to the brain by the optic nerve. The specific structures in an eye are described below:
About the Eye
Cornea
The cornea is the front window of the eye. The cornea is crucially important for allowing good vision because:
- It allows light to pass into the eye: therefore it must remain clear
- The curved shape of the cornea helps to focus light on the retina
Iris
The coloured part of the eye.
Pupil
The opening in the iris that allows light to enter the eye.
Lens
The lens focusses light on the retina at the back of the eye. This lens should be clear to allow light to pass through it and to achieve good vision. Up to approximately 40 years of age, the lens automatically thickens as the person reads. As people get older, the lens loses this ability and people then require reading glasses.
Retina
The retina is the fragile and thin nerve tissue at the back of the eye. It is like the film in a camera and turns light into electrical impulses that can be transmitted to the brain.
Macula
The macula is the central area of the retina responsible for central vision.
Optic Nerve
The optic nerve takes the information from the eye to the brain.