Comparison of Barrett TK Universal II and Barrett Universal II TCRP Formulas in Power Calculations for 3 Presbyopia-Correcting Intraocular Lenses.

PURPOSE: To compare Barrett TK Universal II and Barrett Universal II TCRP calculations in the power calculations for 3 presbyopia-correcting intraocular lenses (PC-IOL).

METHODS

This observational 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 Barrett Universal II calculations, respectively.

RESULTS

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.

CONCLUSION

The novel Barrett TK Universal II formula built in IOLMaster 700 is comparable to TCRP-based Barrett Universal II calculation for IOL power calculation of PC-IOLs, and the convenience of using the Barrett TK Universal II formula should be founded on measurement consistency between devices.