Total Keratometry Measured With a Swept-Source Optical Biometer Versus Anterior Keratometry: From Planning to Postoperative Results.

Abstract

To compare the influence of total keratometry (TK) versus anterior keratometry (K) measured with the swept-source optical biometer IOLMaster 700 (Carl Zeiss Meditec AG) on the planning of toric intraocular lenses (IOLs), and the error in predicted residual astigmatism (PRA). This single-center retrospective study included 247 eyes of 180 patients. In eyes undergoing cataract surgery, the optimal toric IOL was calculated based on K or TK measured with the IOLMaster 700. Two formulas were used to estimate IOL power: Holladay and Barrett Toric. Optimal cylinder power and alignment axis change induced by using TK versus K were reported. PRA by each calculation method was compared with manifest refractive astigmatism. Postoperative refractive astigmatism prediction error was calculated using vector analysis. The optimal toric IOL based on TK compared with K was different in 39.3% of cases with the Holladay formula and 31.6% of cases with the Barrett Toric formula. The use of TK rather than K reduced the centroid error in PRA when calculated with the Holladay formula (P < .001), but not when calculated with the Barrett Toric formula (P = .19). The against-the-rule astigmatism subgroup analysis with the Barrett Toric formula showed a statistically significant decrease of centroid error in PRA with the use of TK compared with K (P = .01). TK compared with K measured with the IOL-Master 700 resulted in a change of optimal toric IOL in almost one-third of cases and decreased the error in PRA in patients with against-the-rule astigmatism. [J Refract Surg. 2023;39(4):257-264.].