Certified Ophthalmic Assistant Practice Exam

The correct answer is the iris. The iris is the part of the eye that contracts in bright light to reduce the size of the pupil, which helps to regulate the amount of light entering the eye. This protective mechanism helps to prevent too much light from entering the eye and damaging the sensitive structures inside. The other options are not correct: - Canthi are the corners of the eye where the upper and lower eyelids meet. - The ciliary body is responsible for changing the shape of the lens to help focus on objects at different distances. - The medial rectus is a muscle responsible for moving the eye medially (towards the nose).