Where is the night blind spot located and what cells does it involve?

Where is the night blind spot located and what cells does it involve?

• A. It is at the optic disc
• B. It is at the cornea
• C. It is at the peripheral retina
• D. It is at the fovea and consists only of cone cells

Answer: (D)

In dim light, night vision relies on rod cells, which are abundant in the peripheral retina. The fovea, however, has no rods and is packed with cone cells for sharp, color vision in bright light. Because cones don’t function well in low light, the central retina around the fovea becomes night-blind. So the night blind spot is at the fovea and consists only of cone cells. The other options don’t fit because the optic disc is the normal blind spot in vision due to a lack of photoreceptors, not specifically a night-related blind spot; the cornea is not part of the retina; and the peripheral retina contains rods and supports night vision, not a night blind area.

In dim light, night vision relies on rod cells, which are abundant in the peripheral retina. The fovea, however, has no rods and is packed with cone cells for sharp, color vision in bright light. Because cones don’t function well in low light, the central retina around the fovea becomes night-blind. So the night blind spot is at the fovea and consists only of cone cells.

The other options don’t fit because the optic disc is the normal blind spot in vision due to a lack of photoreceptors, not specifically a night-related blind spot; the cornea is not part of the retina; and the peripheral retina contains rods and supports night vision, not a night blind area.