What structure surrounds the pupil and regulates the amount of light entering the eye?

What structure surrounds the pupil and regulates the amount of light entering the eye?

• A. Pupil
• B. Iris
• C. Retina
• D. Cornea

Answer: (B)

The iris is the structure that surrounds the pupil and controls how much light enters the eye. It works with two smooth muscle groups: one set constricts the pupil in bright light to let in less light, and the other set dilates the pupil in dim light to let in more light. By changing the size of the opening, the iris helps protect the retina from too much light and also improves vision in various lighting conditions. The pupil itself is the opening, the cornea is the clear surface that bends light at the front, and the retina is the light-detecting layer at the back.

The iris is the structure that surrounds the pupil and controls how much light enters the eye. It works with two smooth muscle groups: one set constricts the pupil in bright light to let in less light, and the other set dilates the pupil in dim light to let in more light. By changing the size of the opening, the iris helps protect the retina from too much light and also improves vision in various lighting conditions. The pupil itself is the opening, the cornea is the clear surface that bends light at the front, and the retina is the light-detecting layer at the back.