Do newer formulas that use measured posterior corneal power improve the accuracy of IOL calculations in eyes following myopic laser vision correction?

PURPOSE: to compare the predictive accuracy of the biometer-embedded Barrett True-K TK and novel total corneal power methods of intraocular lens (IOL) power calculation in eyes with prior laser vision correction (LVC) for myopia.

SETTING: Academic clinical practice.

DESIGN: Retrospective case series.

METHODS: IOL power formulas were assessed using measurements from a swept-source optical coherence biometer. Refractive prediction errors (RPEs) were calculated for the Barrett True-K TK, EVO 2.0, Pearl-DGS, and HofferQST, which use both anterior and posterior corneal curvature measurements. These were compared to the Shammas, Haigis-L, Barrett True-K No History (NH), OCT, and 4-formula average (AVG-4) on the ASCRS post-refractive calculator, and to the Holladay 1 & 2 with non-linear axial length regressions (H1- & H2-NLR).

RESULTS: The study comprised 85 eyes from 85 patients. Only the Barrett True-K TK and EVO 2.0 had mean numerical errors (MNEs) that were not significantly different from 0. The EVO 2.0, Barrett True-K TK, Pearl-DGS, AVG-4, H2-NLR, and Barrett True-K NH were selected for further pairwise analysis. The Barrett True-K TK and EVO 2.0 demonstrated smaller RMSAEs compared to the Pearl-DGS, and the Barrett True-K TK also had a smaller MAE than the Pearl-DGS.

CONCLUSIONS: The Barrett True-K TK and EVO 2.0 formulas had comparable performance to existing formulas in eyes with prior myopic LVC.