Comparison of corneal surgically induced astigmatism calculations based on keratometry measurements made by 2 biometric devices

Purpose:To compare calculated corneal surgically induced astigmatism (SIA) by means of anterior-based keratometry (K) and total keratometry (TK) measurements made by 2 biometric devices.Setting:Ophthalmology Department, Shaare Zedek Medical Center, Jerusalem, Israel.Design:Retrospective, consecutive case series.Methods:The medical records of patients who had undergone cataract surgery through a 2.4 mm temporal clear corneal incision by a single surgeon between March 2018 and November 2020 were retrospectively reviewed. Patients for whom there were preoperative and postoperative K measurements assessed by 2 biometric devices, optical low-coherence reflectometry (OLCR) (Lenstar LS900, Haag-Streit, software v. eye suite i/9.1.0.0) and swept-source optical coherence tomography (SS-OCT) (IOLMaster700, Carl Zeiss Meditec AG, software v. 1.80.6.60340), were identified. Corneal SIA (mean vector value) was calculated by vector analysis for 3 groups: SS-OCT(K), SS-OCT(TK), and OLCR(K). Bivariate analyses were applied for comparisons.Results:147 eyes of 123 patients (73 right eyes and 74 left eyes) were enrolled in the study. The right eye corneal SIA values were 0.09 diopters (D)@136 degrees, 0.09 D@141 degrees, and 0.07 D@123 degrees for the SS-OCT(K), SS-OCT(TK), and OLCR, respectively. The corresponding left eye corneal SIA values were 0.13 D@120 degrees, 0.11 D@123 degrees, and 0.08 D@120 degrees. There were no statistically significant differences between the mean vector value and variance of the corneal SIA for the right (P =.78 and P =.65) and the left (P =.75 and P =.37) eyes of the 3 groups.Conclusions:Corneal SIA values were low (0.07 to 0.13 D) and similar for the SS-OCT and the OLCR biometric devices with standard K measurements. TK measurements yielded similar corneal SIA values compared with anterior corneal-based measurements.