"Miosis" is a medical term that describes the constriction of the pupils. Learn its causes, symptoms, and how to treat it.

Brown and hazel eyes get their color from melanin, the same pigment that colors your skin. The more melanin in the eye, the darker your eye color will appear. But blue eyes don't have any blue ...

The peripheral drift illusion causes us to perceive motion in a still image. A new study shows that the mechanism of this illusion relies on changes in pupil size.

Reptiles are fascinating creatures, not just for their scales, colors, or shapes, but also for their eyes. From mesmerizing ...

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 ...

A study participant with the device used to record pupil movements during sleep. © Neural Control of Movement Lab / ETH Zurich Though sleep is a time to power down ...

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 ...