Comparison Of Barrett Tk Universal Ii And Conventional Barrett Universal Ii Formulas In Power Calculations For 3 Presbyopia-Correcting Intraocular Lenses

To evaluate the total corneal power measurements of IOLMaster and Pentacam and compare Barrett TK Universal II and conventional Barrett Universal II calculations in the power calculations for 3 presbyopia-correcting intraocular lenses (PC-IOL).

This observational study was conducted at Shanghai Aier Eye Hospital. All study procedures were performed in accordance with the tenets of the Declaration of Helsinki and its amendments. The ethics committee of Aier Eye Hospital Group Co. Ltd. approved this study. Written informed consent was obtained from all participants for the usage and publication of their clinical data.

This study involved 64 eyes from 64 patients who prepared to undergo extraction of crystalline lenses combined with PC-IOL (Symfony ZXR00, PanOptix TFNT00, or AT LISA tri 839MP) implantation. All eyes underwent ocular biometric measurements with IOLMaster 700 and Pentacam HR, and the interdevice agreement of measurements including total keratometry (TK, IOLMaster 700) and total corneal refractive power (TCRP, Pentacam HR) was evaluated. IOL power calculations were performed using TK-based Barrett TK Universal II and TCRP-based conventional Barrett Universal II calculations. The mean absolute error (MAE) and the proportion of eyes with spherical equivalent predicted error (PE) within ±0.25 D, ±0.5 D, ±0.75 D, and ±1.00 D were recorded.

Paired t tests showed that the differences in white-to-white diameter, central corneal thickness, anterior chamber depth, and mean TK between IOLMaster 700 and Pentacam HR were slight but significant (all P<0.05), and the differences in recommended IOL power for emmetropia between two Barrett calculations were also significant in 3 PC-IOLs (all P<0.05). The ROC curve showed that the AUC was 0.917 (95% CI, 0.820-0.971) for the absolute value of the difference between TK and TCRP in discriminating the difference of ≥ ±0.5 D in predicted IOL power with best cutoff values of 0.4 D. The MAE of TCRP-based conventional Barrett Universal II calculations was 0.25±0.14 D, and the proportion of eyes with PE within ±0.75 D was 100%.

TCRP-based conventional Barrett Universal II calculation is reliable for IOL power calculation of PC-IOLs. The convenience of using the Barrett TK Universal II formula is founded on measurement consistency between devices, and a difference of 0.4 D between TK and TCRP would lead to a significant difference of 0.5 D in IOL power selection.