Comparison of tendency and accuracy in predicted post-operative refraction and recommended IOL power between IOL Master and VERION before and after optimizing IOL-constant in the VERION
Abstract Background: We assessed the accuracy and tendency of the VERION image-guided system (Alcon) and the intra-ocular lens (IOL) Master 700 (Zeiss), by comparing mean refractive shift (MRS) of predicted post-operative refraction (PPR), mean absolute error (MAE) of PPR, recommended IOL power (RIP) and K-value before and after optimizing the IOL-constant in VERION, to show the importance of optimization.Methods: This retrospective study involved 72 eyes. K-value was measured with both biometers. Axial length (AL) and anterior chamber depth (ACD) measured by the IOL Master were applied to the VERION because it cannot measure these variables. The User group for Laser Interference Biometry (ULIB) IOL-constant for the IOL Master was applied to the VERION before optimizing the IOL constant, since no such official measure was established for it. MRS of PPR, MAE of PPR, RIP and K-value as measured by both biometers were compared before and after optimizing the IOL-constant in the VERION. Finally, correlations between the MRS, MAE, RIP, and K-value were analyzed in the VERION. The Wilcoxon signed-rank test was used for analysis.Results: Compared to the IOL Master, K-value was significantly higher in the VERION. Prior to optimization, MRS of PPR showed a significant myopic shift in the VERION, and MAE of PPR was significantly higher. Additionally, RIP in the VERION was significantly lower. After optimization, there were no significant differences in the MRS of PPR and RIP between the VERION and IOL Master. MAE of PPR in the IOL Master was significantly higher than in the VERION. No significant correlations were found between MRS and MAE of PPR and RIP with K-value in the VERION. Conclusions: Before optimization, the VERION was less reliable in MRS, MAE and RIP than the IOL Master. However, after optimization, the difference in MRS and RIP between the two devices became insignificant. This study indicates that optimization of IOL-constant in the VERION is vital. After optimization, the VERION is more accurate in PPR than the IOL Master.