Relationship between nocturnal intraocular pressure variations and sleep macrostructure

Cross-sectional study conducted in a center with shared expertise in chronobiology. Twelve healthy volunteers underwent a 24-h IOP measurement session. The IOP variations of one eye were continuously estimated using a contact lens sensor (CLS) measuring the changes in corneal curvature related to the IOP and not requiring nocturnal awakening for measurements. The CLS measurement characteristics were evaluated across sleep stages assessed using polysomnography. The CLS signal measurement changes during sleep stage changes were calculated to evaluate the effects of sleep on IOP.A 24-h IOP nyctohemeral rhythm was found in all subjects. During the nocturnal period, IOP signal values were significantly lower during wake stages than during REM and NREM N1, N2 and N3 sleep stages.IOP signal values were significantly higher during the REM stage than during the NREM stages, and progressively decreased as NREM sleep deepened. We found a positive relationship between the micro-arousal index and the nocturnal period CLS signal standard deviation (r=0.76; p=0.024), and a negative relationship between sleep efficiency and the nocturnal period CLS signal standard deviation (r=-0.69; p=0.041).