The visual process

Light rays first cross the cornea. The pupil determines how much light can enter the eye. In darkness, the pupil dilates to allow more light to enter. The lens collects the incoming rays and focuses them on a point in the retina. For optical reasons, an upside down image is generated from the original picture. This image is then transported down the optic nerve to the brain’s visual centre, where the actual image is constructed.

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