Certified Surgical Technologist (CST) Practice Exam

Which layer of the eye is responsible for absorbing light rays and nourishing the retina?

1. Iris

2. Choroid

3. Macula

4. Sclera

The correct answer is: Choroid

The choroid is the layer of the eye that plays a crucial role in absorbing light rays and providing nourishment to the retina. It is located between the retina and the sclera and is rich in blood vessels. The primary function of the choroid is to supply nutrients and oxygen to the outer layers of the retina and to absorb excess light, thus preventing it from scattering within the eye. This ability to minimize light scatter is vital for clear vision. The other layers of the eye, while important, do not have the same primary functions. The iris regulates the amount of light that enters the eye by adjusting the size of the pupil, but it does not nourish the retina. The macula is a small central area of the retina responsible for sharp central vision, especially for activities like reading and driving, but it does not play a role in light absorption or nourishment. The sclera, known as the white part of the eye, serves mainly as protective outer covering, offering structural support but lacking the vascular properties necessary for nourishing the retina. Thus, the choroid is specifically tailored to absorb light and support the retinal health.