title: Estimation of 24-Hour Intraocular Pressure Peak Timing and Variation Using a Contact Lens Sensor.
abstract: OBJECTIVE
  To compare estimates of 24-hour intraocular pressure (IOP) peak timing and variation obtained using a contact lens sensor (CLS) and using a pneumatonometer.
  
  
  METHODS
  Laboratory data collected from 30 healthy volunteers (ages, 20-66 years) in a randomized, controlled clinical trial were analyzed. Participants were housed for 24 hours in a sleep laboratory. One randomly selected right or left eye was fitted with a CLS that monitored circumferential curvature in the corneoscleral region related to the change of IOP. Electronic output signals of 30 seconds were averaged and recorded every 5 minutes. In the contralateral eye, habitual IOP measurements were taken using a pneumatonometer once every two hours. Simulated 24-hour rhythms in both eyes were determined by cosinor fitting. Simulated peak timings (acrophases) and simulated data variations (amplitudes) were compared between the paired eyes.
  
  
  RESULTS
  Bilateral change patterns of average 24-hour data for the group were in parallel. The simulated peak timing in the CLS fitted eye occurred at 4:44 AM ± 210 min (mean ± SD) and the IOP peak timing in the contralateral eye at 4:11 AM ± 120 min (P=0.256, Wilcoxon signed-rank test). There was no significant correlation between the simulated data variations in the paired eyes (P=0.820, linear regression).
  
  
  CONCLUSIONS
  The 24-hour CLS data showed a simulated peak timing close to the 24-hour IOP peak timing obtained using the pneumatonometer. However, the simulated variations of 24-hour data in the paired eyes were not correlated. Estimated 24-hour IOP rhythms using the two devices should not be considered interchangeable.
authors.affiliation: Hamilton Glaucoma Center, Department of Ophthalmology, University of California San Diego, La Jolla, California, United States of America.
authors.forename: John H K
authors.initials: JH
authors.lastname: Liu
authors.affiliation: Hamilton Glaucoma Center, Department of Ophthalmology, University of California San Diego, La Jolla, California, United States of America; Glaucoma Sector, Division of Ophthalmology, Geneva University Hospitals, Geneva, Switzerland.
authors.forename: Kaweh
authors.initials: K
authors.lastname: Mansouri
authors.affiliation: Hamilton Glaucoma Center, Department of Ophthalmology, University of California San Diego, La Jolla, California, United States of America.
authors.forename: Robert N
authors.initials: RN
authors.lastname: Weinreb
mesh_terms: D000328:Adult; D000368:Aged; D003261:Contact Lenses; D005260:Female; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D013997:Time Factors; D014065:Tonometry, Ocular / Q000379:methods*; D055815:Young Adult