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

BACKGROUND: Angle kappa plays a vital role in the implantation of multifocal intraocular lens (MIOL). Large angle kappa is related to a higher risk of postoperative photic phenomena. This study aims to compare preoperative angle kappa in the eyes of cataract patients obtained from the 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 3 times using all devices to obtain angle kappa and pupil diameter. When considering dependent eyes for one individual, angle kappa in both right eyes and left eyes should be analysed separately. The repeatability and reproducibility were evaluated using the within-subject standard deviation (Sw), repeatability (2.77 Sw), and intraclass correlation coefficient (ICC). The difference, correlation, and agreement between devices were evaluated by paired t-tests, Pearson tests, and Bland-Altman analysis, respectively. RESULTS: Intraoperator repeatability and interoperator and intersession reproducibility of angle kappa showed an Sw of less than 0.05 mm, a 2.77 Sw of 0.14 mm or less, and an ICC of more than 0.96. Angle kappa was not significantly different between Pentacam and Lenstar (P > 0.05), while angle kappa was significantly different between Pentacam and iTrace and between Lenstar and iTrace (P 0.05). Positive angle kappa (nasal light reflex) was found in most cataract patients (79.25% to 84.91%) through 3 different devices in both eyes. CONCLUSIONS: The 3 devices provided high intraoperator repeatability and interoperator and intersession reproducibility for angle kappa measurements. The measurement of preoperative angle kappa in the eyes of patients with cataracts by Pentacam and Lenstar has good agreement.