Muscles that move the eyeYou see using your eyes. Light bounces off objects all around you and is picked up by your eyes. They send signals along nerves to the brain. This turns the signals into pictures. Each eyeball measures about 25 millimetres (1 inch) across. It is well protected in a socket inside the skull bone. Six small muscles work together to move the eyeball in different directions.
In dim light, the pupil opens wide, or dilates, (top) to let in as much light as possible. In bright light it gets smaller, or...Read More >>In dim light, the pupil opens wide, or dilates, (top) to let in as much light as possible. In bright light it gets smaller, or contracts (above). The adjustment is automatic—we don’t have any control over it.
Cornea and pupil
The eye is like a tiny camera. It is always taking pictures of the world around you. Light shines into your eye through the dome-shaped front, called the cornea. When we look at an object, light rays enter the eye through a hole called the pupil. This is the black dot in the middle of your eye. The amount of light is controlled by a muscle called the iris, the eye’s coloured part. In dim light, the pupil must be opened wide to let in as much light as possible.
Eye colour is the colour of the iris, which can be green, blue, brown, grey and hazel (a combination of light brown, green and gold). The texture of the iris is unique to each person. Even identical twins have completely different iris textures.
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