Twenty-Four-Hour Intraocular Pressure Indicators Distinguish Normal Tension Glaucoma From Healthy Eyes Measured With a Contact Lens Sensor

Précis: Twenty-four-hour IOP measurements with a CLS showed that among IOP indicators studied, the range of IOP fluctuation was most important and significantly larger in NTG eyes compared with nonglaucoma eyes. Purpose: We conducted the present study to determine (1) the best factor for distinguishing normal tension glaucoma (NTG) and nonglaucoma subjects based on the intraocular pressure (IOP) values measured by a CLS and (2) the optimal cutoff values of that factor. Subjects and Methods: The eyes of 18 nonglaucoma subjects and 26 NTG patients were examined. We evaluated 5 indicators: Maximum IOP value, SD, IOP fluctuation range, the cosine-fit curve amplitude, and the amplitude of dual-harmonic regression values. We determined the indicators' cutoff values to distinguish between nonglaucoma subjects and NTG patients with the area under the curve. Results: The mean IOP values were 12.3±2.7 mm Hg in the nonglaucoma eyes and 12.5±3.1 mm Hg in the NTG eyes (P=0.824). All 5 indicators were significantly higher in the NTG group. The best factor to distinguish the nonglaucoma subjects and NTG patients was the IOP fluctuation range (P<0.0001, area under the curve=0.844); the cutoff level value was 436.5 millivolt equivalents. Conclusions: Twenty-four-hour IOP measurements with a CLS showed that among IOP indicators studied, the range of IOP fluctuation was most important and significantly larger in NTG eyes compared with nonglaucoma eyes.