Comparison of Barrett and Emmetropia Verifying Optical Toric Calculators

Purpose: The purpose of this study was to compare the Barrett (BTC) and Emmetropia Verifying Optical (EVO) Toric Calculators’ performance with regards to prediction of residual post-operative astigmatism after cataract surgery. Methods: This was a secondary analysis of de-identified data that was collected as part of a prospective multicenter clinical trial in which 109 eyes from 109 patients were implanted with a monofocal toric intraocular lens (IOL). Post-operative biometry was used to calculate the predicted post-operative residual astigmatism for each eye using the two different calculators. The vector difference between the actual and predicted residual astigmatism was calculated. Results: The mean absolute astigmatism prediction errors were 0.59 ± 0.38 D and 0.59 ± 0.36 D for the BTC and EVO calculators, respectively (p = 0.98). The centroid of the prediction errors were 0.18 D @ 89° ± 0.68 D and 0.20 D @ 89° ± 0.66 D, respectively (p = 0.21). The proportion of eyes in which the astigmatism prediction error was ≤0.5 D was 50% for BTC and 46% for EVO (p = 0.28). The proportion of eyes in which the post-operative astigmatism orientation was correctly predicted as being against-the-rule, with-the-rule, or oblique was 81% for BTC and 77% for EVO (p = 0.15). Conclusion: The Barrett and Emmetropia Verifying Optical Toric Calculators had similar performance with regards to their astigmatism prediction accuracy.