Comparison of three-point and six-point diurnal intraocular-pressure curves

Abstract

Objective: This study determined if three-point and six-point diurnal intraocular-pressure (IOP) curves are comparable in terms of sensitivity, specificity, and accuracy in detecting swings in IOP measurements of 6 mm Hg or higher.

Methods: This is a retrospective cross-sectional study of 214 glaucoma patients (428 eyes) who underwent six-point diurnal IOP testing. The investigators reviewed their records and generated two sets of data—one for six-point and another for three-point IOP measurements. Diurnal curves were constructed and compared for each set of measurements using univariate analysis of variance.

Results: There was no statistically significant difference (p < .001) between three-point and six-point IOP measurements in detecting IOP swings of 6 mm Hg or higher. The three-point determination has a comparable sensitivity of 70.9%, specificity of 100%, and accuracy of 87.6%. However, there is a likelihood for the IOP change to be underestimated by 1.2 mm Hg in a three-point determination.

Conclusion: The three-point determination (9 p.m., 1 p.m., and 5 p.m.) produces a diurnal curve similar to that of a six-point determination and can be used as a tool in detecting IOP swings in glaucoma patients.