OperationsDifficulty 3/5
How long does it typically take for the eyes to adapt fully to darkness for night operations?
- AAbout 30 minutes
- BAbout 2 hours
- CAdaptation is instantaneous
- DAbout 5 minutes
Show answer and rationale
Correct: A. Full dark adaptation of the rods takes roughly 30 minutes and is lost in seconds when exposed to bright white light; use dim red light and off-center viewing at night.
- D — 5 minutes gives only partial adaptation.
- B — Adaptation is complete well before 2 hours.
- C — Adaptation is a gradual chemical process.