The normal IOP diurnal variation is approximately 2–6 mmHg with the highest values typically occurring:
- A In the early morning (6–8 AM) upon waking ✓
- B At midnight
- C In the early afternoon (2–4 PM)
- D In the evening (8–10 PM)
Correct answer: A. In the early morning (6–8 AM) upon waking
Explanation
IOP follows a diurnal pattern with the highest values in the early morning hours (approximately 6–8 AM), corresponding to the circadian peak of aqueous humour production driven by sympathetic and cortisol-mediated mechanisms after waking. IOP is typically lowest in the afternoon/early evening. This diurnal variation is important clinically because single afternoon IOP measurements may miss elevated peak pressures in glaucoma suspects. Diurnal phasing (multiple IOP measurements at different time points) can reveal peak pressures and help guide treatment decisions.
Reference: Khurana Comprehensive Ophthalmology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.