Thresholds were determined after which adaptation condition?

• A. Light adaptation
• B. Both dark and light adaptation
• C. Dark adaptation
• D. Immediate after light exposure

Answer: (C)

Thresholds in vision testing depend on the current adaptation state of the eye. After dark adaptation, photoreceptors, especially rods, recover their sensitivity as rhodopsin is regenerated, so the eye becomes much more sensitive to faint light. This lowers the detection threshold for dim stimuli, which is why thresholds are determined after a period of darkness. In bright or immediate after light exposure, the eye is less sensitive (cones dominate and rhodopsin is bleached), giving higher thresholds.