What is the primary function of the pupil in the eye?

The primary function of the pupil in the eye is to allow light to enter the eye. The pupil is the opening in the center of the iris, and its size can change in response to varying light conditions. When the surrounding environment is bright, the pupil constricts to reduce the amount of light entering the eye, which helps to prevent damage to the retina and enhances visual acuity by increasing the depth of field. Conversely, in low-light conditions, the pupil dilates to permit more light to enter, improving visibility.

While other structures in the eye are involved with focusing light or providing protection, the direct role of the pupil is to regulate the amount of light that reaches the retina, which is essential for optimal vision. The ability of the pupil to adjust its size is a crucial mechanism that supports our vision across different lighting environments.