What happens to the pupil while reading or performing near vision tasks?

When engaging in near vision tasks, such as reading, the pupil constricts. This physiological response is part of the eye's accommodation process, which helps optimize focus on close objects.

The constriction of the pupil reduces the amount of light entering the eye, which can enhance depth of field and improve visual acuity for nearby objects. This process also minimizes blurriness from peripheral light that could disrupt clarity when focusing on items at close range.

In contrast, the dilation of the pupil typically occurs in low light conditions to maximize light intake, while remaining unchanged or transforming into a slit is not associated with standard near vision activities. Therefore, the constriction of the pupil is a vital adjustment that supports effective near vision focus by narrowing the aperture through which light enters.