Comparison Of Barrett Rx And Berdahl-Hardten Back-Calculator Tools For Calculating Toric Intraocular Lens Realignment Due To Postoperative Residual Astigmatism

To compare the effectiveness of Barrett RX and Berdahl-Hardten in determining the necessary postoperative toric IOL axis to minimize residual astigmatism. In addition, the time required to perform the calculations was evaluated for each online tool to assess their efficiency in clinical practice.

Department of Ophthalmology, Goethe-University, Frankfurt, Germany.

A retrospective analysis was performed on 49 eyes of 48 patients who underwent cataract surgery with toric IOL implantation and required postoperative IOL rotation due to residual astigmatism. The recommended IOL rotation was calculated using both the Barrett RX and Berdahl-Hardten formulas (astigmatismfix.com). The accuracy of the two tools was assessed by the reduction in residual astigmatism after IOL realignment. In addition, the time taken to perform each calculation was recorded and compared.

The prediction of the two back-calculator tools yielded analogous results, with the recommended axis for the lowest residual astigmatism and the predicted residual astigmatism exhibiting a maximum discrepancy of 3 degrees and 0.03 diopters (D), respectively. The comparison between predicted residual astigmatism and actual astigmatism was 0.4±0.3 D for both formulas. Preliminary findings indicate that the Barrett RX formula required a longer calculation time (mean 140 seconds) compared to the Berdahl-Hardten formula (mean 80 seconds) (p < 0.001).

The preliminary observations suggest that the two methods will yield equivalent results in predicting the ideal toric IOL rotation. Both methods provide a suitable approach for postoperative refinement of toric IOL positioning, thereby contributing to the reduction of residual astigmatism. However, it should be noted that Barrett RX required a longer calculation time than the Berdahl-Hardten formula.