Accuracy of the Barrett Universal II formula integrated into a commercially available optical biometer when using a preloaded single-piece intraocular lens

PURPOSE: To compare the commonly used formulas for intraocular lens (IOL) selection using IOLMaster(®)700 (Carl Zeiss Meditec) and to evaluate the Barrett Universal II (BU-II) formula accuracy when using the Vivinex™ iSert(®) XY1 IOL (Hoya Corporation Medical Division). METHODS: A retrospective chart review was performed that included patients who underwent uneventful cataract surgery with in-the-bag insertion of Vivinex™ iSert(®) XY1 IOL. Prediction errors at 3 months postoperative of IOLMaster(®) 700 with Haigis, Holladay 1, SRK/T, and BU-II formulas were compared. As a subgroup analysis, we focused on the axial length (AL) and IOL power. AL subgroup analysis was based on the following AL subgroups: short (<22.5 mm), medium (22.5–25.5 mm), and long (>25.5 mm). IOL power subgroup analysis was based on the following IOL power subgroups: low (≤18.0 diopters [D]), medium (18.5–24.0 D), and high (≥24.5 D). RESULTS: This study included 590 eyes of 590 patients. Overall, the four IOL calculation formulas appeared to be similarly accurate. In the long AL subgroup, the BU-II formula had a significantly lower absolute error (AE) than the Holladay 1 formula. In the low-power subgroup, the BU-II formula had a significantly lower AE than the Holladay 1 and SRK/T formulas. On the other hand, in the high-power subgroup, the BU-II formula was significantly less accurate than the SRK/T formula and also appeared to be worse than the Holladay 1 formula (P = 0.052). CONCLUSION: The BU-II formula might be less accurate when using a Vivinex™ iSert(®) XY1 IOL of 24.5 D or greater.