Hourly Awakening vs Continuous Contact Lens Sensor Measurements of 24-Hour Intraocular Pressure

Abstract

All studies of 24-hour intraocular pressure (IOP) rhythm conducted to date have used repeated IOP measurements requiring nocturnal awakenings, potentially disturbing sleep macrostructure. To evaluate the effects on sleep architecture and IOP rhythm of hourly awakening vs a contact lens sensor (CLS) to continuously monitor IOP without awakening. Cross-sectional study at a referral center of chronobiology among 12 young healthy volunteers, with a mean (SD) age of 22.3 (2.3) years. Volunteers underwent two 24-hour IOP measurement sessions during a 2-month period. The eye order and session order were randomized. During one session, the IOP of the first eye was continuously monitored using a CLS, and the IOP of the fellow eye was measured hourly using a portable noncontact tonometer (session with nocturnal hourly awakening). During the other session, the IOP of the first eye was continuously monitored using a CLS, and the IOP of the fellow eye was not measured (session without nocturnal awakening). Overnight polysomnography was performed during the 2 sessions. A nonlinear least squares, dual-harmonic regression analysis was used to model the 24-hour IOP rhythm from the CLS data. Comparisons of acrophase, bathyphase, amplitude, and the midline estimating statistic of rhythm were used to evaluate the effect of hourly awakening on IOP rhythm. To evaluate the effects of hourly awakening on sleep architecture, comparisons of sleep structure were used, including total sleep period, rapid eye movement, wake after sleep onset, absolute and relative total sleep time, and non-rapid eye movement sleep (N1, N2, and N3). A 24-hour IOP rhythm was found in all individuals for the sessions with and without awakening (P < .05). Hourly awakening for nocturnal IOP measurements increased wake after sleep onset (P = .04) but did not seem to change total sleep time, total sleep period, sleep efficiency, or slow-wave and rapid eye movement sleep stage duration (P > .30). Hourly awakening during noncontact tonometer IOP measurements did not seem to alter the mean variables of the 24-hour IOP pattern evaluated using CLS, including signal, maximum signal, minimum signal, acrophase, and bathyphase (P > .15). The 24-hour IOP rhythms seem to be unaffected by hourly nocturnal awakening for IOP measurements in young healthy individuals.