Comparison of Preoperative Angle Kappa Measurements in the Eyes of Cataract Patients Obtained from Pentacam Scheimpflug System, Optical Low-Coherence Reflectometry, and Ray-Tracing Aberrometry

Abstract

Background Angle kappa plays a vital role in the implantation of multifocal intraocular lens (MIOLs). Large angle kappa is related to higher risk of postoperative photic phenomena. This study aims to compare preoperative angle kappa in the eyes of cataract patients obtained from Pentacam Scheimpflug system (Pentacam), optical low-coherence reflectometry (Lenstar), and ray-tracing aberrometry (iTrace). Methods One hundred thirteen eyes of 113 patients with cataracts were included. Each eye was examined by the devices to obtain angle kappa (X-Y Cartesian coordinates) and pupil diameter. When considering dependent eyes for one individual, angle kappa in right eyes and left eyes should be analyzed separately. The difference, correlation, and agreement between values for horizontal and vertical components of angle kappa were evaluated by paired t-tests, Pearson or Spearman tests, and Bland‑Altman analysis, respectively. Results No significant differences in the pupil diameter were found between Pentacam and Lenstar or Lenstar and iTrace in both eyes (P > 0.05). Positive angle kappa (nasal light reflex) was found in most cataract patients (79.25–84.91%) through 3 different devices in both eyes. The significant differences of angle kappa were not found between Pentacam and Lenstar compared to Pentacam and iTrace or Lenstar and iTrace in both eyes (P > 0.05). Pentacam and Lenstar showed strong correlation in the horizontal and vertical components of angle kappa compared to Pentacam and iTrace or Lenstar and iTrace in both eyes (r = 0.906 to 0.939). The 95% limits of agreement (LoA) in the horizontal and vertical components of angle kappa with Pentacam and Lenstar were narrower respect to Pentacam and iTrace or Lenstar and iTrace in both eyes. Conclusions There were no differences, strong correlation, and good agreement in angle kappa with Pentacam and Lenstar for cataract patients. Based on these findings, the measurement of preoperative angle kappa in the eyes of patients with cataracts by Pentacam and Lenstar has good agreement, and can be used interchangeably, but caution is warranted for outcomes-based iTrace that report angle kappa.