Predictive Accuracy of Intraocular Lens Power Calculation: Comparison of Optical Low-Coherence Reflectometry and Immersion Ultrasound Biometry

Abstract

Purpose: To evaluate the accuracy of intraocular lens (IOL) power calculation using an optical low-coherence reflectometry (OLCR) biometer and to compare the results with those obtained with an immersion ultrasound biometry (IUB). Methods: Biometric measurements were obtained with OLCR and IUB combined with automated keratometry before cataract surgery. The mean prediction error (MPE) and the mean absolute error (MAE) were calculated for five various IOL formulas (SRK II, SRK/T, Holladay, Hoffer Q, and Haigis), and the two different biometry methods were compared. Results: Optical low-coherence reflectometry measured a slightly longer axial length (mean difference, 0.05 mm; P<0.001) and a shallow anterior chamber depth (mean difference, 0.12 mm; P<0.001). With OLCR, the MPEs (+/- SD) calculated by the SRK II, SRK/T, Holladay, Hoffer Q, and Haigis formulas were -0.04 +/- 0.53, -0.04 +/- 0.56, -0.03 +/- 0.53, -0.04 +/- 0.56, and -0.02 +/- 0.56, respectively (P<0.0001). The mean differences (+/- SD) for MAE were statistically significant between OLCR and IUB; SRK II (0.47 +/- 0.44 vs. 0.61 +/- 0.49, P<0.0001), SRK/T (0.39 +/- 0.4 vs. 0.49 +/- 0.45, P=0.0004), Holladay (0.37 +/- 0.37 vs. 0.47 +/- 0.41, P<0.0001), Hoffer Q (0.4 +/- 0.39 vs. 0.5 +/- 0.43, P<0.0001), and Haigis (0.4 +/- 0.39 vs. 0.7 +/- 0.51, P<0.0001). Conclusion: The OLCR produces a more predictable refractive outcome than IUB, with patients' spherical equivalent being more likely to be closer to their target refraction.