What is the iris responsible for?

The iris plays a crucial role in the function of the eye by determining its color and regulating the amount of light that enters. It is composed of muscles that can contract or expand, allowing it to adjust the size of the pupil. When exposed to bright light, the iris constricts the pupil to minimize light entry, protecting the retina from excessive brightness. Conversely, in low light conditions, the iris dilates the pupil to allow more light to reach the retina, which enhances visibility. This dual function of color determination and light regulation is essential for optimal vision in varying light conditions.

In contrast, the structure that focuses light onto the retina is primarily the lens, not the iris. The connection between the lens and the rest of the eye is facilitated by the zonules or ciliary ligaments, which are not part of the iris. Additionally, tears are produced by the lacrimal glands, separate from the functions of the iris.