What type of pupil results from stimulation of the iris sphincters?

A constricted pupil results from stimulation of the iris sphincters. The iris sphincter muscle, also known as the pupillary constrictor, is responsible for narrowing the pupil in response to light or during focusing on near objects. This process is part of the pupillary light reflex and accommodates for better vision when viewing close objects, which improves depth of field and sharpness of the image on the retina.

The normal physiological response is for the pupils to constrict when exposed to bright light, helping protect the retina from excessive brightness. In contrast, a fixed pupil does not respond to changes in light or accommodation, often indicating a neurological issue or damage. A dilated pupil indicates that the iris sphincter is not functioning properly or is inhibited, often due to the action of certain drugs or in response to low light. Therefore, stimulation of the iris sphincters appropriately leads to pupil constriction, making it the correct choice.