It's made up of at least ... A slit pupil, with two sides that can close like a sliding door, is far better at this task, which is why so many nocturnal eyes have slit pupils.

People on TikTok are putting their eye ... pick up all the details of their iris as they their eye close to the camera. The iris is the coloured part of the eye that surrounds the pupil and ...

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.

Fish like roach that migrate between lakes and streams have larger eyes with bigger pupils, improving vision in low light.