Kaplan Nursing Entrance Practice Exam

Which cells in the eye are primarily responsible for night vision?

1. Cones

2. Rods

3. Optic nerves

4. Photoreceptors

The correct answer is: Rods

Rods are the cells in the eye primarily responsible for night vision due to their high sensitivity to low light levels. These photoreceptor cells are more numerous than cones, particularly in the peripheral regions of the retina, which allows for better detection of light in dim conditions. Rods contain a pigment called rhodopsin, which is highly effective in absorbing light, even in very low illumination. This makes them crucial for scotopic vision, allowing us to see in dark environments where cone cells, which are responsible for color perception and function best under bright light, are less effective. Understanding the role of rods is essential for comprehending how the eye adapts during low-light conditions, as they enable us to detect shapes and movements even when color and fine detail perception are diminished.