Comparison of corneal thickness measurement with the Pentacam, the PARK1 and an ultrasonic pachymeter

Purpose: The aim was to determine the agreement between PARK1 pachymetric readings and measurements made with the Pentacam and ultrasonic pachymetry. Methods: In this prospective study, we enrolled refractive surgery patients free of other ocular conditions and performed Pentacam and PARK1 acquisitions followed by ultrasonic pachymetry. We recorded pachymetric readings on the centre, apex and thinnest point with the Pentacam, corneal thickness values of the apex and minimum readings from the PARK1, and the central corneal thickness with the ultrasonic system. Data were compared using t-tests, and the Pearson correlations and 95 limits of agreement (LoA) of all pairs were determined. Results: The mean age of the 47 participants was 32 ± 10.4years and data from their right eyes were used. Overall, ultrasonic measurements were significantly higher than all readings from the PARK1 and the Pentacam. The smallest difference was between the PARK-apex and Pentacam-apex readings (0.2 ± 11μm); the 95 LoA of this pair gave a width of 43.7μm (-21.7 to 22.0μm). The smallest width pertained to the Pentacam-centre and ultrasound-centre paired readings; the width was 32.5μm (-21.8 to 11.8μm), while the mean difference was -5.54 ± 8μm. Conclusion: The PARK1 measurements of the apical corneal thickness can be a substitute for central corneal pachymetry with an ultrasonic device, provided that the range of agreement is taken into consideration in the interpretation of the results. Similar studies on populations with different corneal conditions such as keratoconus are needed. © 2011 Optometrists Association Australia