Iris

Author: Sara Ferreira, MD • Reviewer: Dimitrios Mytilinaios, MD, PhD
Last reviewed: June 12, 2023
Reading time: 1 minute

The iris is the circular coloured part of the eye. It is part of the vascular layer of the eye - the other two components are the choroid and the ciliary body.

The central opening of the iris is the pupil. Within the iris there are smooth muscle fibers that control the size of the pupil.

The smooth muscle fibers within the iris form the sphincter pupillae muscle, which constricts the pupillary opening, and the dilator pupillae muscle, which dilates the pupil.

Terminology	English and latin: Iris
Function	Controls the size of the pupils

Learn everything about the anatomy of the eyeball with the following study unit!

Sources

All content published on Kenhub is reviewed by medical and anatomy experts. The information we provide is grounded on academic literature and peer-reviewed research. Kenhub does not provide medical advice. You can learn more about our content creation and review standards by reading our content quality guidelines.

Drake RL, Vogl AW, Mitchell WMA. Gray’s anatomy for students. 4th ed. 2020.

Moore, K. L., Dalley, A. F., & Agur, A. (2017). Clinically oriented anatomy (8th ed.). Lippincott Williams and Wilkins.

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Iris

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