The pupil controls how much light enters the eye, allowing for clear vision. In low light, pupils widen to let in more light, and in bright light, they narrow to prevent too much light from entering.

The PERRLA test is a standard eye examination that can help healthcare professionals diagnose a wide range of health issues, including vision problems and some neurological conditions. People may ...

Researchers at the University of California (UC) San Diego School of Medicine say that with further developments measuring how quickly a person’s pupil dilates while they are taking cognitive tests ...