The Predictive Accuracy of Barrett Toric Calculator Using Measured Posterior Corneal Astigmatism Derived from Swept Source-OCT and Scheimpflug Camera

Abstract PURPOSE: To compare the performance of Barrett toric calculator incorporated with measured posterior corneal astigmatism (PCA) derived from IOL Master 700 and Pentacam HR versus predicted PCA. METHODS: The predicted residual astigmatism using Barrette toric IOL calculator with predicted PCA, measured PCA from IOL Master 700 and measured PCA from Pentacam were calculated with the preoperative keratometry and intended IOL axis with modification. The vector analysis was performed to calculate the mean absolute prediction error (MAE), the centroid of the prediction error and the percentage of eyes with a prediction error within ±0.50 D, ± 0.75 D, and ± 1.00 D. RESULTS: In 57 eyes of 57 patients with mean age of 70.42±10.75 years, the MAE among the three calculation methods were 0.59±0.38 D (Predicted PCA) , 0.60±0.38 D (Measured PCA from IOL Master 700) and 0.60±0.36 D (Measured PCA from Pentacam) with no significant difference, either in the whole sample, the WTR eyes and the ATR eyes (F = 0.078, 0.306 and 0.083, p=0.925, 0.739 and 0.920, respectively). Measured PCA obtained from IOL Master 700 resulted in one level reduction (from Tn to Tn-1) in 49.12% eyes in cylindrical model selection, while measured PCA obtained from Pentacam resulted in one level reduction of toric model selection in 18.18% eyes. CONCLUSION: The present study suggested that the incorporation of measured PCA values derived from IOL Master 700 and Pentacam produce comparable clinical outcome with the predicted PCA mode in Barrette toric calculator.