Comparison of New Optical Biometry and Optical Low-Coherence Reflectometry for IOL Power Calculation
Purpose
To evaluate the agreement of a new partial coherence interferometry optical biometer (AL Scan, Nidek CO, Aichi, Japan) with optical low-coherence reflectometry device (Lenstar LS 900, Haag-Streit AG, Koeniz, Switzerland).
Methods
Thirty five eyes of 35 patients with cataract were included in this prospective study. Biometry was performed with the new biometer and the Lenstar. Comparisons were performed for axial length (AL), keratometry (K) over 2.4 mm and 3.3 mm diameter, anterior chamber depth (ACD), white to white (WTW). IOL power calculations and postoperative predictability of the devices were also compared. The agreement in ocular biometry and IOL power between the 2 devices was evaluated by the Bland-Altman method.
Results
Statistical analysis showed good agreement between devices for AL, ACD, K values and WTW and no clinically significant difference was found between devices for all IOL power formulae. In addition, the 95% limits of agreement between the two devices was narrower when the 2.4 mm, rather than the 3.3 mm, diameter was selected on the AL Scan to measure K but these variations were not clinically significant. Regarding the difference in the mean absolute error statistically significance was found only for SRK/T (p=0.041) whereas not for the other formulae (p > 0.05). No error exceeded 1.50 Diopters.
Conclusion
The new PCI biometer provided valid measurements compared with the Lenstar, indicating that these devices can be used interchangeable for IOL power calculations for routine cataract surgery.