Comparison of dynamic contour tonometry (Pascal®) with pneumotonometry and Goldmann tonometry

To compare the intraocular pressure measurements as defined by the Pascal tonometer, the Goldmann tonometer and the pneumotonometer. METHODS: This was an observational clinical study, which included two hundred and five randomly selected subjects recruited from the Ophthalmology Department. The intraocular pressure measurements were performed with each tonometry technique in a randomized order. RESULTS: The Pascal's intraocular pressure measurement was significantly higher than that measured by the other two tonometers (p<0.05). The quality data of Pascal was: optimum in 27.3% (56 of 205 patients), acceptable in 42% (86 of 205 patients) and unacceptable in 23.4% (48 of 205 patients). In 7.3% (15 of 205 patients) it was impossible to obtain any measurement using Pascal. A weak correlation coefficient between the Pascal and the Goldmann, and between Pascal and the pneumotonometer was found. The Bland-Altman method of measurement using these tonometers showed a high degree of discordance. CONCLUSION: As reported by others authors, the Pascal's intraocular pressure measurement is higher than that of the Goldmann tonometer. The measurement differs from 0.7 to 4.4 mmHg. In corneas with pathology, it is very difficult or even unacceptable to measure the intraocular pressure using the Pascal tonometer

Reproducibility and clinical relevance of the ocular response analyzer in nonoperated eyes: corneal biomechanical and tonometric implications

To assess the reproducibility of the ocular response analyzer (ORA) in nonoperated eyes and the impact of corneal biomechanical properties on intraocular pressure (IOP) measurements in normal and glaucomatous eyes. METHODS: In the reliability study, two independent examiners obtained repeated ORA measurements in 30 eyes. In the clinical study, the examiners analyzed ORA and IOP-Goldmann values from 220 normal and 42 glaucomatous eyes. In both studies, Goldmann-correlated IOP measurement (IOP-ORAg), corneal-compensated IOP (IOP-ORAc), corneal hysteresis (CH), and corneal resistance factor (CRF) were evaluated. IOP differences of 3 mm Hg or greater between the IOP-ORAc and IOP-ORAg were considered outcome significant. RESULTS: Intraexaminer intraclass correlation coefficients and interexaminer concordance correlation coefficients ranged from 0.78 to 0.93 and from 0.81 to 0.93, respectively, for all parameters. CH reproducibility was highest, and the IOP-ORAg readings were lowest. The median IOP was 16 mm Hg with the Goldmann tonometer, 14.5 mm Hg with IOP-ORAg (P < 0.001), and 15.7 mm Hg with IOP-ORAc (P < 0.001). Outcome-significant results were found in 77 eyes (29.38%). The IOP-ORAc, CH, and CRF were correlated with age (r = 0.22, P = 0.001; r = -0.23, P = 0.001; r = -0.14, P = 0.02, respectively), but not the IOP-ORAg or IOP-Goldmann. CONCLUSIONS: The ORA provides reproducible corneal biomechanical and IOP measurements in nonoperated eyes. Considering the effect of ORA, corneal biomechanical metrics produces an outcome-significant IOP adjustment in at least one quarter of glaucomatous and normal eyes undergoing noncontact tonometry. Corneal viscoelasticity (CH) and resistance (CRF) appear to decrease minimally with increasing age in healthy adults