Certified Paraoptometric (CPO) Practice Exam 2025

Which part of the eye contains cells that detect light?

1. Iris

2. Lens

3. Retina

4. Ciliary Muscle

The correct answer is: Retina

The retina is the part of the eye that contains cells specifically designed to detect light. It is a thin layer of tissue located at the back of the eyeball, and it is composed of photoreceptor cells known as rods and cones. Rods are responsible for vision in low light conditions and help with peripheral vision, while cones are crucial for color perception and detail in bright light. When light hits these photoreceptors, they convert the light signals into electrical impulses that are transmitted to the brain via the optic nerve, allowing us to perceive images. Other parts of the eye, such as the iris, lens, and ciliary muscle, play roles in the regulation of light entry and focusing but do not possess the ability to detect light themselves.