Comparison of Keratometry and Total Corneal Power, as measured by a swept-source OCT-based optical biometer, for IOL power calculation in Asian eyes.

Abstract

To investigate whether standard keratometry (K) or total corneal power (TCP) lead to more accurate refractive outcomes for intraocular lens (IOL) power calculation. Public hospital. Retrospective evaluation of a diagnostic test instrument. Preoperatively all patients underwent optical biometry with the Anterion (Heidelberg), a swept-source optical coherence tomographer providing both K and TCP. The same IOL model was implanted in all cases. The whole sample was divided into a training dataset, used to optimize the formula constants, and a testing dataset, used to investigate the spherical equivalent prediction error (SEQ-PE) of 8 IOL power formulas. Trueness, precision and accuracy were evaluated by means of the robust two-sample t-test. Cochran's Q test was performed to assess whether the percentage of eyes with an SEQ-PE within each threshold was significantly different; in such an event, the McNemar test was then applied. Both the training and testing datasets included 317 eyes. No significant differences were detected for trueness, due to constant optimization. Precision and accuracy were better when K was entered, although a statistically significant difference was observed only with the EVO (precision: p = 0.02 and accuracy: p = 0.03) and Haigis formula (p <0.01 for both precision and accuracy). No significant differences were observed for the percentage of eyes with an absolute SEQ-PE within any threshold. With most formulas, IOL power calculation is not more accurate when TCP is used instead of K.