What is Pupillary Reflex

[Anandi]

The pupillary reflex is the reflex contraction of the sphincter muscle of the iris in response to a bright light (or certain drugs) causing the pupil to become smaller.

The reflex controls the diameter of the pupil, in response to the intensity (luminance) of light that falls on the retina of the eye. Greater intensity light causes the pupil to become smaller (allowing less light in), whereas lower intensity light causes the pupil to become larger (allowing more light in). Thus, the pupillary light reflex regulates the intensity of light entering the eye.

It is a normal response and dependent on the function of the optic nerves and oculomotor nerves.