Medically reviewed by Christine L. Larsen, MD Medications, trauma, and medical conditions can lead to abnormally small pupils ...

Pupillometry measures the size and reactivity of the pupil, the dark circle at the eye’s centre through which light enters. Typically, the pupil contracts and dilates depending on the amount of ...

Nocturnal animals tend to have proportionally bigger eyes than humans do. They also tend to have pupils that open more widely in low light. So, at the outset, nocturnal eyes gather more light than ...