Using 24-hr ocular dimensional profile recorded with a sensing contact lens to identify primary open-angle glaucoma patients with intraocular pressure constantly below the diagnostic threshold

PURPOSE

To evaluate the use of a 24-hr ocular dimensional profile recorded with a contact lens sensor (CLS) combined with a single tonometric intraocular pressure (IOP) reading to indicate the potential for exceeding the diagnostic threshold for normal tension glaucoma (NTG) in Japanese patients.

METHODS

Intraocular pressure (IOP) of untreated Japanese NTG patients was measured with tonometry every 3 hr from 9:00 to 24:00. The subsequent day a 24-hr CLS (SENSIMED Triggerfish, Sensimed AG, Lausanne, Switzerland) profile was recorded on the same eye. Patients initially diagnosed as NTG were reclassified as NTG when the measured IOP values were consistently <20 mmHg or as primary open-angle glaucoma (POAG) when IOP was ≥20 mmHg in at least 1 measurement. For each patient and each IOP time-point, IOP values were combined with information provided by the CLS profile ('classifier') to indicate the potential for exceeding the diagnostic threshold value. Statistical analyses were performed for each classifier.

RESULTS

A total of 65 patients, 28 males and 37 females (mean ages: 50.8 ± 14.6 years and 52.6 ± 10.2 years, respectively), were analysed. Following IOP diurnal measurement, five patients (7.7%) were reclassified as POAG. Two classifiers (15:00 CLS and 18:00 CLS) showed high sensitivity and negative predictive value (100%), identifying all the POAG patients.

CONCLUSION

Contact lens sensor information can be used in conjunction with a single tonometric reading to determine patients' potential of having IOP levels exceeding the diagnostic threshold within a 24-hr period, without the need to perform a 24-hr tonometric curve. This would allow clinicians to identify POAG patients who may otherwise be eventually misclassified as NTG.

First-in-human continuous 24-hour measurement of intraocular pressure and ocular pulsation using a novel contact lens sensor

BACKGROUND/AIMS

This study assessed the feasibility of a novel contact lens device for intraocular pressure (IOP) and ocular pulse amplitude (OPA) continuous measurements over 24 hours.

METHODS

This prospective, open-label, single-centre, non-randomised study included glaucoma and healthy subjects. IOP and OPA values acquired by the pressure-measuring contact lens (PMCL) device in one patient's eye at the beginning of the measurement were compared with tonometry values (Goldman applanation tonometry (GAT) and dynamic contour tonometry (DCT)) in the same eye just before PMCL placement. Furthermore, IOP and OPA values measured with PMCL on the study eye during a water drinking test (WDT) were compared with DCT values in the fellow eye. Comparisons were performed using t-tests with 95% Confidence Intervals.

RESULTS

Twenty-four-hour IOP and OPA curves were obtained for eight subjects. The mean IOP difference between PMCL and tonometry on the same eye was within ±5 mm Hg in 75% (GAT) and 87.5% (DCT) of subjects. IOP variations due to WDT were detected by PMCL and DCT, showing an average increase of 2.43 and 1.85 mm Hg, respectively. Differences between PMCL and DCT for IOP variations in fellow eyes were within ±5 mm Hg for 97.2% of time points. The difference between OPA in fellow eyes was within ±5 mm Hg for 85.5% of the time points.

CONCLUSIONS

This first-in-human study is a proof-of-concept for 24-hour continuous measurements of IOP and OPA with the PMCL. This device is non-invasive and has good comparability with standard tonometry.