Source:http://linkedlifedata.com/resource/umls/id/C0034121
MSH: The aperture in the iris through which light passes.,CSP: opening at the center of the iris of the eye through which light enters.,NCI: The round opening in the center of the iris (the colored tissue that makes the eye color at the front of the eye). The pupil changes size to let light into the eye. It gets smaller in bright light and larger as the amount of light decreases.