24-HOUR INTRAOCULAR PRESSURE RHYTHM IN YOUNG HEALTHY SUBJECTS EVALUATED WITH CONTINUOUS MONITORING USING CONTACT LENS SENSOR

Abstract

Purpose: To evaluate 24-h intraocular pressure (IOP) rhythm reproducibility during repeated continuous 24-h IOP monitoring with non-contact tonometry (NCT) and a contact lens sensor (CLS) in healthy subjects

Methods: Subjects were housed in a sleep laboratory and underwent four 24-h sessions of IOP measurements over a 6-month period. After randomized attribution, the IOP of the first eye was continuously monitored using the CLS Sensimed TriggerFish® and the IOP of the fellow eye was measured hourly using the Pulsair Intellipuff non-contact tonometer. Two sessions with NCT measurements in one eye and CLS measurements in the fellow eye, one session with CLS measurements in only one eye, and one session with NCT measurements in both eyes were performed. A nonlinear least-squares dual harmonic regression analysis was used to model the 24-h IOP rhythm. Comparison of acrophase, bathyphase, amplitude, the midline estimating statistic of rhythm (MESOR), IOP values, IOP changes and agreement were evaluated in the three tonometry methods.

Results: A significant nyctohemeral IOP rhythm was found in 31 out of 36 sessions (86%) using NCT and in all sessions (100%) using CLS. Hourly awakening during NCT IOP measurements did not significantly change the mean phases of the 24-h IOP pattern evaluated using CLS in the contralateral eye. Throughout the sessions, intraclass correlation coefficients (ICCs) of the CLS acrophase (0.6 [0-0.9]; p=0.03), CLS bathyphase (0.7 [0.1-0.9]; p=0.01), NCT amplitude (0.7 [0.1-0.9]; p=0.01) and NCT MESOR (0.9 [0.9-1]; p<0.01) were significant. The highest numbers of hourly IOP values (n=18) and hourly IOP changes (n=9) with fair to good agreement in a 24-h cycle were obtained using NCT and CLS, respectively. When performing NCT measurements in one eye and CLS measurements in the contralateral eye, the IOP change at each time point normalized from the first measurement (9:00 AM) were not symmetric individually or within the population.

Conclusions: The CLS is an accurate and reproducible method to characterize the nyctohemeral IOP rhythm in healthy subjects but does not estimate the absolute IOP value in millimeters of mercury corresponding to the relative variation of the electrical signal measured.

Keywords: 568 intraocular pressure • 465 clinical (human) or epidemiologic studies: systems/equipment/techniques