An evaluation of the accuracy of toric intraocular lens power calculation based on measured total corneal refractive power.

PURPOSE

To evaluate a method using measured values of total corneal refractive power (TCRP) for a manufacturer's online calculator by comparing it with the Barrett toric calculator (BTC) and Kane toric calculator (KTC) combined with simulated keratometry values (SimK).

METHODS

This was a retrospective case series. Patient records were reviewed to identify the patients who had biometry with the IOL Master 700 and Pentacam recorded before toric IOL implantation and refractive follow-up data after implantation. The predicted error in residual astigmatism was calculated by vector analysis according to the calculation methods and the measurements used.

RESULTS

A total of 70 eyes of 56 patients were included. The mean absolute astigmatism prediction errors were 0.6 ± 0.32, 0.59 ± 0.35, and 0.61 ± 0.35 D for the ATC, BTC, and KTC calculators, respectively (P = 0.934), and the centroid of the prediction errors were 0.3 D @ 178°, 0.11 D @ 102°, and 0.09 D @ 147°, respectively (P = 0.23). In the with-the-rule subgroup, the centroid of the prediction error was 0.34 D @ 176° for ATC and was the highest among the three calculation methods (P = 0.046).

CONCLUSION

The ATC, BTC, and KTC calculators had similar performance with regards to their astigmatism prediction accuracy. The ATC calculator combined with 4.0-mm apex/ring readings of TCRP was slightly intended to result in against-the-rule residual astigmatism.