Agreement between Pentacam HR and Visionix VX650 system for corneal and anterior chamber parameters

PURPOSE: To evaluate the agreement in anterior segment measurements obtained with Pentacam HR and Visionix VX650 topographers, in terms of keratometry, pachymetry and anterior chamber parameters in healthy eyes. METHODS: Inclusion criteria consisted of healthy eyes with no history of ocular pathology or surgery. Measurements of central corneal thickness (CCT), minimum corneal thickness (MCT), anterior and posterior keratometry (K1, K2), anterior chamber depth (ACD), and anterior chamber angle (ACA) were taken using the Pentacam HR and Visionix VX650. Differences between devices were assessed with paired Student's t-tests, and agreement was evaluated using Bland-Altman plots. RESULTS: Fifty-five eyes from 55 healthy participants mean age 32.55 ± 12.60 years) were examined. Anterior keratometry and MCT showed clinically acceptable agreement between devices, with no significant differences (p > 0.164). Pentacam HR reported steeper posterior keratometry, smaller ACD, lower CCT and larger ACA values compared with VX650 (p < 0.001). For CCT and MCT, ranges of agreement were large, with values of ± 27.07 and 55.41 μm, respectively. However, the ranges of agreement for anterior K1 and K2 were smaller, with values of ± 0.11 and 0.11 mm, respectively. Likewise, the ranges of agreement for ACD and ACA were also clinically significant, with a clear trend of VX650 to provide longer ACD measurements and lower ACA estimates. CONCLUSIONS: Anterior corneal keratometry measured with the Pentacam HR and Visionix VX650 exhibit acceptable inter-device agreement. However, caution should be exercised regarding their interchangeability, especially when making decisions that require precise thickness (refractive surgery screening) or anterior chamber parameters (phakic intraocular lens implantation).