Comparison of the ultrasonographic method with 2 partial coherence interferometry methods for intraocular lens power calculation

Background: The accuracy of biometric measurements, particularly axial length, is critical for precise intraocular lens (IOL) power calculation and predictable refractive outcomes after cataract surgery. Partial coherence interferometry-based systems represent progress toward measurements that are more precise and reliable. The purpose of this study was to evaluate a new noncontact optical biometer (Lenstar; Haag-Streit AG, Koeniz, Switzerland) using optical low-coherence reflectometry and to compare the biometric measurements (including axial length, keratometry, anterior chamber depth, and IOL power) with those obtained from current clinical instrumentation.

Methods: Biometric measurements were obtained with Lenstar, IOL Master V.5 (Carl Zeiss Meditec AG, Jena, Germany), and A-scan applanation ultrasound scan combined with a Javal-type keratometer in 234 eyes of 234 subjects scheduled for cataract surgery. IOL power was calculated using Sanders, Retzlaff, Kraff II, Hoffer Q, and Holladay 1 formulas.

Results: The axial length readings were similar (P = 0.997). The anterior chamber depth measurements obtained by IOL Master were slightly smaller than those obtained with other devices (P = 0.092). The means of the average keratometry readings were 0.65 and 0.61 diopters lower when measured with Lenstar as compared with IOL Master and the Javal-type keratometer, respectively (P = 0.002). All of the measurements were tightly correlated (P < 0.001). For anterior chamber depth measurements, however, the correlation was slightly weaker. Using the above-mentioned formulas, the mean IOL power measurements were similar. These measurements were tightly correlated (P < 0.001). The level of agreement was acceptable and comparable between devices.

Conclusions: The findings from this study show the validity and clinical utility of Lenstar compared with instrumentation currently used in clinical practice for assessing ocular biometry and IOL power calculation in cataractous eyes.