The Eye - Medical Conditions [back]
The Eye – Structure
The eye works rather like a camera. Light rays are reflected from an object and refracted (bent) by the cornea through the pupil. The pupil is an opening surrounded by a ring of muscle called the iris. The iris can dilate and constrict to control the size of the pupil and therefore the amount of light entering the eye.
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Light is further refracted by the lens through the vitreous – a clear jelly like substance- to focus on the retina at the back of the eye. |
| The retina is a delicate tissue that is sensitive to light, like camera film. It contains a fine network of blood vessels. |
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The image the retina receives is upside down; it is converted to electrical impulses and transmitted through the optic nerve to the brain, where it is translated and perceived upright.
At the centre of the retina is the macula, which is a small area the size of a grain of rice. The macula is highly specialised and is responsible for allowing us to see fine detail for tasks such as reading and also enables us to recognise colours. The other parts of the retina give us peripheral vision, but cannot resolve very fine detail.
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