Astigmatism Orientation after Deep Anterior Lamellar Keratoplasty for Keratoconus and Its Correlation with Preoperative Peripheral Corneal Astigmatism

Purpose:To evaluate the orientation of keratometric astigmatism (KA) after deep anterior lamellar keratoplasty (DALK) for keratoconus and its correlation with preoperative peripheral KA.Methods:This is a retrospective, single-center observational study including keratoconic patients undergoing DALK between January 2016 and January 2017 with regular astigmatism postoperatively. The orientation of postoperative KA was classified as with-The-rule (WTR), against-The-rule, or oblique and was correlated with the corresponding preoperative peripheral KA, calculated by the sinusoidal fitting of points of the axial keratometric power map at 8 mm diameter.Results:Forty-one keratoconic eyes were included, with the most common orientation of KA post-DALK being WTR (65.9%), followed by against-The-rule (19.5%) and oblique (14.6%). A significant correlation was found between preoperative peripheral KA and post-DALK KA regarding axis (P < 0.001, r = 0.88) and power (P = 0.0128, r = 0.23).Conclusions:The axis of post-DALK astigmatism and to a lesser extent its respective power in keratoconic eyes can be predicted using the preoperative peripheral KA, with "WTR" being the most common astigmatic orientation.