Efficacy of a contact lens sensor for monitoring 24-h intraocular pressure related patterns.
OBJECTIVE
To study performance of a contact lens sensor (CLS) for 24-hour monitoring of IOP-related short-term patterns and compare with IOP obtained by pneumatonometry.


METHODS
Prospective clinical trial. Thirty-one healthy volunteers and 2 glaucoma patients were housed for 24 hours in a sleep laboratory. One randomly selected eye was fitted with a CLS (Triggerfish, Sensimed, Switzerland), which measures changes in ocular circumference. In the contralateral eye, IOP measurements were taken using a pneumatonometer every two hours with subjects in the habitual body positions. Heart rate (HR) was measured 3 times during the night for periods of 6 minutes separated by 2 hours. Performance of CLS was defined in two ways: 1) recording the known pattern of IOP increase going from awake (sitting position) to sleep (recumbent), defined as the wake/sleep (W/S) slope and 2) accuracy of the ocular pulse frequency (OPF) concurrent to that of the HR interval. Strength of association between overall CLS and pneumatonometer curves was assessed using coefficients of determination (R2).


RESULTS
The W/S slope was statistically significantly positive in both eyes of each subject (CLS, 57.0 ± 40.5 mVeq/h, p<0.001 and 1.6 ± 0.9 mmHg/h, p<0.05 in the contralateral eye). In all, 87 CLS plots concurrent to the HR interval were evaluated. Graders agreed on evaluability for OPF in 83.9% of CLS plots. Accuracy of the CLS to detect the OPF was 86.5%. Coefficient of correlation between CLS and pneumatonometer for the mean 24-h curve was R2 = 0.914.


CONCLUSIONS
CLS measurements compare well to the pneumatonometer and may be of practical use for detection of sleep-induced IOP changes. The CLS also is able to detect ocular pulsations with good accuracy in a majority of eyes.


BACKGROUND
ClinicalTrials.gov NCT01390779.
Hamilton Glaucoma Center and Department of Ophthalmology, University of California San Diego, La Jolla, California, United States of America; Glaucoma Sector, Department of Ophthalmology, Geneva University Hospitals, Geneva, Switzerland.
Kaweh
K
Mansouri
Hamilton Glaucoma Center and Department of Ophthalmology, University of California San Diego, La Jolla, California, United States of America.
Robert N
RN
Weinreb
Hamilton Glaucoma Center and Department of Ophthalmology, University of California San Diego, La Jolla, California, United States of America.
John H K
JH
Liu
D000328:Adult; D016022:Case-Control Studies; D003261:Contact Lenses; D005260:Female; D005901:Glaucoma / Q000175:diagnosis*; D006339:Heart Rate; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D013997:Time Factors; D014065:Tonometry, Ocular / Q000379:methods*; D055815:Young Adult