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Diurnal variations in human corneal thickness
C L Harper1, M E Boulton, D Bennett
1University Department of Ophthalmology, Manchester.
The British Journal of Ophthalmology
|December 1, 1996
Summary
Human corneal thickness increases during sleep and shows significant variation throughout waking hours. Overnight changes do not fully represent the total diurnal variation, which is greater than previously reported.
Area of Science:
- Ophthalmology
- Corneal Physiology
Background:
- Corneal thickness is known to increase during sleep.
- The extent and pattern of diurnal variation in corneal thickness require further investigation.
Purpose of the Study:
- To investigate the diurnal variation in human corneal thickness over a 48-hour period.
- To compare overnight corneal thickness changes with overall diurnal variations.
Main Methods:
- Central corneal thickness was measured in eight healthy adults using ultrasonic pachymetry.
- Measurements were taken over 48 hours, including pre-sleep, upon waking, and at regular intervals throughout the day.
Main Results:
- Mean corneal thickness was 546 (14) microns.
- An average overnight increase of 5.5% (2.9%) and a maximum diurnal increase of 7.2% (2.8%) were observed.
- Significant individual variations in corneal thickness changes were noted, with some subjects showing continued increases after waking.
Conclusions:
- Corneal thickness increases during sleep, with substantial variations also occurring during waking hours.
- Overnight corneal thickness changes are not fully representative of diurnal variations.
- The actual diurnal variation in human corneal thickness is greater than previously estimated.
