"Dilator iridis" refers to the dilator muscle of the iris in the human eye. This smooth muscle controls the dilation of the pupil, allowing more or less light into the eye. Synonyms for "dilator iridis" include "pupillary dilator muscle" and "radial muscle of iris". These terms describe the anatomical structure responsible for expanding or contracting the pupil. The proper functioning of the dilator iridis is essential for regulating the amount of light reaching the retina and ensuring clear vision. Without this muscle, the pupil would remain stationary, affecting vision in different lighting conditions. Understanding the synonyms for "dilator iridis" helps in effectively communicating its role and importance in ocular function.