Yes, the iris is comprised of muscles. More specifically, it contains two sheets of smooth muscle: the iris sphincter muscle and the iris dilator muscle. These muscles work in opposition to control pupil size, regulating the amount of light entering the eye.
Iris Muscle Function: Light Regulation
- Iris Sphincter Muscle: This circular muscle constricts the pupil, reducing the amount of light entering the eye. This is a crucial function in bright light conditions. Wikipedia describes it as a constrictor of the pupil.
- Iris Dilator Muscle: This radial muscle dilates (widens) the pupil, allowing more light to enter the eye. This is important in low-light conditions to maximize vision. ScienceDirect notes its role in dilation.
The coordinated actions of these two muscles ensure optimal visual acuity in various lighting conditions. Britannica and Cleveland Clinic both confirm this dual muscle structure and its function in light adjustment.
The Iris: More Than Just Muscle
While the muscles are the key functional components, the iris is also composed of other structures, including the pigmented epithelium which contributes to eye color. This complex structure ensures not only light regulation but also plays a role in overall eye health. American Academy of Ophthalmology offers further details on iris anatomy.
