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Nocturnal dip in the optic nerve head perfusion
1University Eye Hospital, Basel, Switzerland.
Japanese Journal of Ophthalmology
|March 15, 2000
Summary
Optic nerve head (ONH) blood flow shows significant reductions at midnight in healthy individuals. This nocturnal dip in ONH perfusion requires further investigation into its physiological and clinical significance.
Area of Science:
- Ophthalmology
- Physiology
- Circadian Rhythms
Background:
- Physiological parameters like blood pressure exhibit circadian variations.
- Diurnal fluctuations in optic nerve head (ONH) circulation have not been previously investigated.
Purpose of the Study:
- To investigate the 24-hour pattern of ONH blood flow variations in healthy subjects.
- To establish baseline ONH circulation dynamics over a diurnal cycle.
Main Methods:
- Laser Doppler flowmetry (LDF) was used to measure ONH blood flow.
- Measurements were taken over a 24-hour period in 15 healthy volunteers at specified intervals (08:00, 12:00, 16:00, 20:00, 24:00, 08:00).
Main Results:
- ONH perfusion showed significant temporal variations.
- Mean LDF-flow and volume decreased significantly at midnight compared to daytime levels (P =.0015 and P =.04, respectively).
- No significant differences in mean LDF-velocity were observed at any time point.
Conclusions:
- Healthy subjects exhibit a significant reduction in ONH perfusion during the night.
- The physiological and clinical implications of this nocturnal dip in ONH perfusion warrant future research.