Comparison of the quality score of intraocular pressure and ocular pulse amplitude values measured by the Pascal dynamic contour tonometer

The Pascal dynamic contour tonometer (PDCT) is designed to measure intraocular pressure (IOP) largely independent of the corneal properties. It is equipped with a digital LCD screen that displays the IOP, the ocular pulse amplitude (OPA) and the quality score (Q) of the measurements [range 1 (excellent) to 5 (poor)]. The manufacturer has recommended discarding the IOP and OPA values of Q4 and Q5. The aim of our study was to assess if IOP and OPA measurements with Q3 are acceptable for clinical and research purposes. This is a prospective, observational study in which both patients with ocular hypertension or glaucoma and healthy subjects were enrolled; three consecutive PDCT IOP measurements were performed on all participants. Only patients and subjects with Q1, Q2 and Q3 recorded together were eligible. Only one eye per subject was considered for statistical analysis. The mean PDCT IOP and OPA were taken for statistical analyses. An ANOVA test for repeated measures was used to compare the differences between PDCT IOP and OPA Q1, Q2, and Q3 scores. A total of 87 subjects met the inclusion criteria. Mean PDCT (±SD) IOP were 17.5 ± 3.4 mmHg for Q1, 17.6 ± 3.3 mmHg for Q2 and 17.9 ± 3.3 mmHg for Q3 (P > 0.05). Mean OPA Q1, Q2 and Q3 were 2.5 ± 0.9, 2.5 ± 1.0 and 2.5 ± 1.0 mmHg, respectively, and were not statistically different. Based on these results, we concluded that the IOP and OPA values with Q1, Q2 or Q3 measured by PDCT are not significantly different and can therefore be taken into account indiscriminately for clinical and research purposes.