Comparison of two optical biometers in intraocular lens power calculation

Aims: To compare the consistency and accuracy in ocular biometric measurements and intraocular lens (IOL) power calculations using the new optical low-coherence reflectometry and partial coherence interferometry. Subjects and Methods: The clinical data of 122 eyes of 72 cataract patients were analyzed retrospectively. All patients were measured with a new optical low-coherence reflectometry system, using the LENSTAR LS 900 (Haag Streit AG)/ALLEGRO BioGraph biometer (Wavelight., AG), and partial coherence interferometry (IOLMaster V. 5.4 [Carl Zeiss., Meditec, AG]) before phacoemulsification and IOL implantation. Repeated measurements, as recommended by the manufacturers, were performed by the same examiner with both devices. Using the parameters of axial length (AL), corneal refractive power (K1 and K2), and anterior chamber depth (ACD), power calculations for AcrySof SA60AT IOL were compared between the two devices using five formulas. The target was emmetropia. Statistical analysis was performed using Statistical Package for the Social Sciences software (SPSS 13.0) with t-test as well as linear regression. A P value < 0.05 was considered to be statistically significant. Results: The mean age of 72 cataract patients was 64.6 years +/- 13.4 [standard deviation]. Of the biometry parameters, K1, K2 and [K1 + K2]/2 values were significantly different between the two devices (mean difference, K1: -0.05 +/- 0.21 D; K2: -0.12 +/- 0.20 D; [K1 + K2]/2: -0.08 +/- 0.14 D. P < 0.05). There was no statistically significant difference in AL and ACD between the two devices. The correlations of AL, K1, K2, and ACD between the two devices were high. The mean differences in IOL power calculations using the five formulas were not statistically significant between the two devices. Conclusions: New optical low-coherence reflectometry provides measurements that correlate well to those of partial coherence interferometry, thus it is a precise device that can be used for the pre-operative examination of cataract patients.