Which layer of the eye contains photoreceptor cells?

The correct answer is the layer of the eye that contains photoreceptor cells is the retina. The retina is a thin layer of tissue located at the back of the eye, which plays a critical role in vision. Within the retina, there are two main types of photoreceptor cells: rods and cones. Rods are responsible for vision in low light conditions, while cones function in brighter light and are essential for color vision and visual acuity.

The photoreceptors convert light into electrical signals, which are then transmitted to the brain through the optic nerve, allowing us to perceive images. The presence of these cells in the retina is what enables the eye to capture visual information and sends it to the brain for processing.

In contrast, the cornea serves as the eye's outermost lens, helping to focus light, but it does not contain photoreceptor cells. The sclera is the white outer layer that provides structure and protection for the eye and also lacks photoreceptor cells. The iris is responsible for controlling the amount of light that enters the eye by adjusting the size of the pupil but also does not contain photoreceptors. Therefore, the retina is the definitive layer that houses the essential photoreceptor cells for vision.