What is the pupil’s function in the eye?

The pupil's primary function is to permit light to enter the eye. It acts as an adjustable opening that regulates the amount of light that reaches the retina, which is essential for clear vision. The size of the pupil changes in response to different lighting conditions; it constricts in bright light and dilates in dim light. This adjustment is crucial for optimal vision and helps to prevent damage to the retina from excessive light exposure.

Focusing light onto the retina is primarily the role of the cornea and the lens of the eye, which work together to refract light appropriately. Protecting the eye from bright lights, while a function of the pupil constricting, is a secondary effect of its primary role in regulating light entry. Providing shape to the eyeball is a task of the eye's structural components like the sclera and the vitreous humor, not the pupil.