Certified Ophthalmic Assistant Practice Exam 2025 – 400 Free Practice Questions to Pass the Exam

The iris is the part of the eye that regulates the amount of light that enters the eye. It is a thin, circular structure located around the pupil, which is the opening in the center of the iris. The iris contains muscles that can contract or dilate, allowing it to adjust the size of the pupil in response to varying light conditions. For instance, in bright light, the iris constricts the pupil to reduce the amount of light entering the eye and protect the retina, while in dim light, it dilates the pupil to allow more light to enter.

The cornea, while essential for focusing light onto the retina, does not have the capability to regulate light intake. Instead, it primarily performs the role of refracting light. The lens also plays a crucial role in focusing light on the retina, but it does not adjust to control the light entering the eye. The retina, on the other hand, is responsible for detecting light and converting it into neural signals for the brain but does not control the amount of light that comes through the pupil. Each of these structures has distinct functions, but it is the iris that has the specific role of managing light entry into the eye.