Analysis of Continuous 24-Hour Intraocular Pressure Patterns in Glaucoma

Abstract

PURPOSE.To present a method to analyze circadian intraocular pressure (IOP) patterns in glaucoma patients and suspects undergoing repeated continuous 24-hour IOP monitoring.METHODS. Forty patients with established (n ¼ 19) or suspected glaucoma (n ¼ 21) underwent ambulatory 24-hour IOP monitoring on two sessions 1 week apart using a contact lens sensor (CLS). The CLS provides its output in arbitrary units (a.u.). A modified cosinor rhythmometry method was adapted to the CLS output to analyze 24-hour IOP patterns and their reproducibility. Nonparametric tests were used to study differences between sessions 1 and 2 (S1 and S2). Patients pursued their routine daily activities and their sleep was uncontrolled. CLS data were used to assess sleep times. RESULTS.Complete 24-hour data from both sessions were available for 35 patients. Mean (SD) age of the patients was 55.8 6 15.5 years. The correlation of the cosinor fitting and measured CLS values was r ¼ 0.38 (Spearman r; P < 0.001) for S1, r ¼ 0.50 (P < 0.001) for S2, whereas the correlation between S1 and S2 cosinor fittings was r ¼ 0.76 (P < 0.001). Repeated nocturnal acrophase was seen in 62.9% of patients; 17.1% of patients had no repeatable acrophase. The average amplitude of the 24-hour curve was 143.6 6 108.1 a.u. (S1) and 130.8 6 68.2 a.u. (S2) (P ¼ 0.936).CONCLUSIONS. Adapting the cosinor method to CLS data is a useful way for modeling the rhythmic nature of 24-hour IOP patterns and evaluating their reproducibility. Repeatable nocturnal acrophase was seen in 62.9% of patients. (Clinical Trials.gov number, NCT01319617.) (Invest Ophthalmol Vis Sci. 2012;53:8050-8056) DOI:10.1167/iovs.12-10569 E levated intraocular pressure (IOP) is a major risk factor for glaucoma onset 1 and progression. 2 Current treatment for glaucoma is based on lowering of IOP to reduce the rate of progression. 3 Treatment success is frequently expressed as reaching a target range of IOP on subsequent clinic visits when IOP is generally assessed using Goldmann applanation tonometry (GAT). Despite its limitations, 4 the Goldmann technique is widely accessible, easy to perform, and remains the worldwide standard procedure for measuring IOP. Although it generates reliable results, it can provide only a single temporal value that does not reflect the dynamic nature of IOP and its circadian rhythm. 5,6 As a consequence, variations in IOP are commonly noticed, but not well recognized, and often underappreciated in the management of glaucoma patients. These variations are the result of complex interactions between external environmental stimuli and the biologic IOP rhythm. Although previous studies have implicated peak IOP as a major contributor to glaucoma progression, 7,8 data on the time course of IOP rhythms and their reproducibility in glaucoma patients remain scarce. Evidence suggests that reproducibility of several daytime IOP measurements with GAT is only moderate at best in glaucoma patients.9-11 Important shortcomings of these studies, next to the limited number of available IOP measur...

Contact Lens Sensor Triggerfish – What Do We Know?

“…The wake-sleep-slope is attributed to this change of the head position. 13 A comparison of the CLS profile with an IOP profile of the fellow eye (measured with PT) showed a very good correlation of values (correlation coefficient R2+0.914). 17 Other working groups could not demonstrate this correlation.…”

“…A weakness of this study was the inclusion of patients on and off therapy, because the therapy might have had an influence on the profile. 13 Mottet et al examined 12 healthy subjects in a sleep laboratory repeatedly with the CLS (on three different days) and hourly non-contact tonometry (NCT, on four different days) to evaluate the rhythm reproducibility and symmetry between the eyes. 14 The reproducibility between CLS and NCT showed poor to fair correlation.…”

24-Hour Contact Lens Sensor Monitoring of Intraocular Pressure-Related Profiles in Normal-Tension Glaucoma and Rates of Disease Progression

“…Alternative methods of IOP measurement are needed to fully characterize a patient's true IOP profile and to examine the effect of short-and long-term IOP changes on disease progression [13] .…”

Emerging glaucoma therapeutics

“…Using this device, a recently published study showed a nocturnal peak in tension occurs in about 70% of all patients with diagnosed or suspected POAG. 29 These continuous measurement devices will likely have a significant impact on the therapy of POAG going forward.…”