Astigmatism with TK more Accurate for Toric Calculation?

FAM Han BorSingapore Speaker Astigmatism with TK more Accurate for Toric Calculation?This presentation explores the impact of Total Keratometry (TK) on the calculation of toric intraocular lenses (IOLs), focusing on the role of posterior corneal astigmatism (PCA) in refractive outcomes. Drawing on large datasets and recent studies, it highlights that PCA is a significant factor in toric IOL planning, with traditional keratometry often leading to over-correction of with-the-rule (WTR) and under-correction of against-the-rule (ATR) astigmatism. The presentation reviews evidence showing that using measured PCA values, rather than predicted ones, improves the accuracy of postoperative astigmatism prediction, especially when the steep axis of PCA is non-vertical. Comparative analysis of various toric IOL formulas demonstrates that EVO formulas with measured PCA yield the smallest centroid errors and highest percentage of eyes within 0.50D of predicted astigmatism, particularly in cases with non-vertical PCA. The findings underscore the importance of incorporating TK and measured PCA into toric IOL calculations to optimise refractive outcomes for cataract patients.