Total 24-hour IOP measurements with a CLS revealed that the range of IOP fluctuation in NTG eyes was the most significant and significantly larger than in nonglaucoma eyes. The goal of the current study was to determine the best factor and determine the optimal cutoff values for that factor in order to distinguish between individuals with normal tension glaucoma (NTG) and patients without glaucoma based on intraocular pressure (IOP) measurements collected by a CLS. Around 26 NTG patients and 18 individuals without glaucoma had their eyes examined. The maximal IOP value, SD, IOP fluctuation range, cosine-fit curve amplitude, and the amplitude of dual-harmonic regression values were the 5 indicators they analyzed. Using the area under the curve, they established the indicators’ cutoff values to discriminate between nonglaucoma participants and NTG patients. In eyes without glaucoma, the mean IOP measurements were 12.3±2.7 mm Hg, while in eyes with NTG, they were 12.5±3.1 mm Hg (P=0.824). The NTG group had significantly higher values for all 5 indicators. IOP fluctuation range was the most effective factor for differentiating between non-glaucoma participants and NTG patients (P=0.0001, area under the curve=0.844); the cutoff level value was 436.5 millivolt equivalents. IOP indicators were measured over the course of 24 hours using a CLS, and it was discovered that the range of IOP fluctuation was the most significant and much larger in NTG eyes than in nonglaucoma eyes.