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T. Kida, J.H. K. Liu, D.F. Kripke, R.N. Weinreb; Twenty–Four–Hour Changes in Central Corneal Thickness in Healthy Young Adults . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4425.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate the 24–hour changes of central corneal thickness and their relationship with the 24–hour changes of intraocular pressure (IOP) in healthy young adults.
Fifteen healthy young volunteers (age 20–25 years) were housed for 1 day in a sleep laboratory. An 8–hour accustomed sleep period was offered each subject. Every two hours, central corneal thickness was measured sitting and supine by an ultrasound pachymeter and sitting IOP by a non–contact tonometer. In the 16–hour diurnal/wake period, measurements were taken after 5–minute bed rest and then after 5 minutes in the sitting position. In the 8–hour nocturnal/sleep period, measurements were taken supine and then after 5 minutes in the sitting position.
Mean values of central corneal thickness were 549.1 ± 12.0 µm (mean ± SEM) and 565.8 ± 13.2 µm in the supine position and 549.6 ± 11.8 µm and 562.7 ± 12.7 µm in the sitting position during the diurnal and nocturnal periods, respectively. The peak of mean central corneal thickness was at 3:30AM and the trough of mean central corneal thickness was at 11:30AM–1:30PM. The nocturnal central corneal thickness was significantly higher than the diurnal central corneal thickness. The mean peak and trough were 570.4 ± 13.6 µm and 546.5 ± 11.6 µm in the supine position and 565.2 ± 13.4 µm and 545.9 ± 11.5 µm in the sitting position. The nocturnal IOP was also higher than the diurnal IOP. The peak IOP was at 5:30–7:30AM and the trough IOP was at 9:30PM. The mean IOP peak value was 13.3 ± 0.8 mmHg and the mean trough value was 11.1 ± 0.4 mmHg.
In this group of healthy young adults, both central corneal thickness and IOP were higher during the nocturnal period than during the diurnal period. The peak central corneal thickness occurred a few hours earlier than the peak IOP. Although central corneal thickness may influence IOP in healthy young individuals, the nocturnal IOP elevation is not precisely associated with the increase of central corneal thickness.
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