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

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 OCT (SS-OCT) 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-, 3-, and 6-months postoperative visits were considered for vector analysis of SIAK and SIATK. RESULTS Centroids in right and left eyes were 0.26 dpt @5°/ 0.31 dpt @1° for SIAK and 0.27 dpt @4°/ 0.34 dpt @1° for SIATK. Centroids for difference vectors (DV) K-TK in right and left eyes were 0.02 dpt @ 176°/ 0.03 dpt @6°. The mean SIA magnitudes in right and left eyes were 0.48±0.41 dpt and 0.50±0.37 dpt for SIAK and 0.53±0.42 dpt and 0.54±0.40 dpt 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°. CONCLUSION Overall, we observed differences in K- and TK-derived SIA, and changes in SIA magnitude over time. For post-surgical 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