24-Hour Monitoring of Intraocular Pressure Fluctuations Using a Contact Lens Sensor: Diagnostic Performance for Glaucoma Progression

PURPOSE. The purpose of this study was to compare 24-hour intraocular pressure (IOP) related fluctuations monitoring between 2 groups of visual field progression rates in patients with open angle glaucoma (OAG). METHODS. Cross-sectional study performed at Bordeaux University Hospital. Twenty -four-hour monitoring was performed using a contact lens sensor (CLS; Triggerfish; SENSIMED, Etagnieres, Switzerland). Progression rate was calculated using a linear regression of the mean deviation (MD) parameter of the visual field test (Octopus; HAAG-STREIT, Switzer-land). Patients were allocated into two groups: group 1 with an MD progression rate <-0.5 dB/year and group 2 with an MD progression rate >=-0.5 dB/year. An automatic signal-processing program was developed and a frequency filtering of the monitoring by wavelet transform analysis was used to compare the output signal between the two groups. A multivariate classifier was performed for prediction of the faster progression group. RESULTS. Fifty-four eyes of 54 patients were included. The mean progression rate was -1.09 +/- 0.60 dB/year in group 1 (n = 22) and -0.12 +/- 0.13 dB/year in group 2 (n = 32). Twenty-four-hour magnitude and absolute area under the monitoring curve were significantly higher in group 1 than in group 2 (group 1: 343.1 +/- 62.3 millivolts [mVs] and 8.28 +/- 2.10 mVs, respectively, group 2: 274.0 +/- 75.0 mV and 6.82 +/- 2.70 mVs respectively, P < 0.05). Magnitude and area under the wavelet curve for short frequency periods ranging from 60 to 220 minutes were also significantly higher in group 1 (P < 0.05). CONCLUSIONS. The 24-hour IOP related fluctuations characteristics, as assessed by a CLS, may act as a risk factor for progression in OAG. In association with other predictive factors of glaucoma progression, the CLS may help adjust treatment strategy earlier.