What is the function of the iris?

The function of the iris is primarily to regulate the amount of light that enters the eye. It achieves this by adjusting the size of the pupil, which is the opening in the center of the iris. When there is bright light, the iris constricts the pupil, reducing the amount of light that can enter the eye to prevent damage to the retina and enhance visual acuity. In low light conditions, the iris dilates the pupil to allow more light to enter, improving visibility.

Understanding this function is crucial because it impacts our ability to see clearly in different lighting conditions. The iris thus plays a vital role in controlling exposure to light and maintaining optimal conditions for vision.