We shine it in the eye to make sure that the pupil is brisk and responsive to light then we will cross it back and fourth to make sure that they are both working and affecting each other ...

In children, a white glow in the pupil (often seen in flash photographs), crossed eyes, or vision issues can be early signs of retinoblastoma. In adults, cancers like uveal melanoma could appear ...

Psychopaths and non-psychopaths were watched closely, and the results showed that while the pupils of non-psychopaths' eyes dilated when viewing something scary, the psychopaths' pupils did not.