The condition characterized by delayed termination of phototransduction, causing temporary blindness when transitioning to bright light, is called?

• A. Bradyopsia
• B. Cone dystrophy
• C. Congenital stationary night blindness
• D. Retinitis pigmentosa (RP)

Answer: (A)

The key idea is how quickly phototransduction is terminated and the retina resets after a change in lighting. In bradyopsia, the shutoff of the cone phototransduction cascade is slowed, so after you move into brighter light the cone signal takes longer to terminate. That delay means the visual signal can’t rapidly adapt to the new, higher light level, producing a temporary period of reduced vision or “temporary blindness” during the transition to bright light.

This is distinct from cone dystrophy, where cones progressively deteriorate and central/color vision worsens over time; congenital stationary night blindness mainly affects night vision through the rod pathway and isn’t about delayed bright-light recovery; and retinitis pigmentosa is a degenerative disease with gradual peripheral vision loss and night blindness. Bradyopsia specifically describes the slow recovery of cone function after exposure to bright light, leading to the transient difficulty with rapid light adaptation.