Pupil

The opening at the center of the iris through which light enters the eye. The iris causes the pupil to dilate and contract in response to stimuli such as light, extreme emotion, and certain drugs.

The pupil is in direct line with the macula, allowing light to be concentrated where vision is clearest. The iris will contract the pupil in conditions of bright light and will widen the pupil in low light in order to optimize vision.

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