Dilated pupils are also caused by drug use, sexual attraction, brain injury, eye injury, certain medications, or benign episodic unilateral mydriasis (BEUM). The size of your pupils can say a lot ...

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 ...