Characteristics of surgically induced astigmatism after standardized microincisional cataract surgery with a superior limbal incision

Abstract

Purpose: To determine (1) if measurements of surgically induced astigmatism (SIA) as measured by keratometry (K) and total keratometry (TK) differ (2) if SIA affects the magnitude and/or meridian of keratometric astigmatism (3) if SIA evolves over time. Setting: Tertiary care center. Design: Retrospective data analysis. Methods: A swept-source optical coherence tomography biometry dataset (IOLMaster700) consisting of 498 eyes (327 patients) from a tertiary care center was analyzed. For all eyes preoperative and postoperative biometric measurements at 1-month, 3-month, and 6-months postoperative visits were considered for vector analysis of SIAK and SIATK. Results: Centroids in right and left eyes were 0.26 diopters (D) @5 degrees/0.31 D @1 degree for SIAK and 0.27 D @4 degrees/0.34 D @1 degree for SIATK. Centroids for difference vectors K-TK in right and left eyes were 0.02 D @ 176 degrees/0.03 D @6 degrees. The mean SIA magnitudes in right and left eyes were 0.48 ± 0.41 D and 0.50 ± 0.37 D for SIAK and 0.53 ± 0.42 D and 0.54 ± 0.40 D for SIATK. In eyes with ATR astigmatism, an increase in postoperative astigmatism magnitude was more common than a decrease. More than 30% of eyes showed changes in the meridian of more than 15 degrees. Conclusions: Overall, we observed differences in K- and TK-derived SIA, and changes in SIA magnitude over time. For postsurgical interventions, postoperative astigmatism meridian values should be measured to base treatments. Astigmatism magnitude showed a tendency to decrease for steep-meridian incisions and to increase in flat-meridian incisions.