As we have mentioned before, your eyes have lenses. Look at the diagram of the eye. The main parts of an eye are the cornea, the pupil, the iris, the lens and the retina.

The cornea is a clear material at the front of the eye that protects your eye. When you scratch your eye, it is the cornea that is damaged.

The pupil is the opening into the eye. It is where light enters the eye and allows you to see things. The iris is the colored part of the eye that surrounds the pupil. It contains muscles that surround the pupil and open and close the pupil to regulate the amount of light that is allowed to enter the eye.

When there is a lot of light, the pupil closes down to only a small hole and lets in just a little of the light. When it is dark and you need more light in order to be able to see, the iris causes the pupil to open up to allow more light in.