What is iris reflex?

The iris reflex, also known as the pupillary reflex, is the automatic constriction or dilation of the pupil in response to light intensity. When exposed to bright light, the muscles in the iris contract, reducing the size of the pupil to protect the retina from excessive brightness. Conversely, in dim light, the pupil dilates to allow more light to enter the eye for better vision. This reflex is a crucial part of the eye's ability to adapt to varying lighting conditions.