Accuracy of predicted refraction with multifocal intraocular lenses using two biometry measurement devices and multiple intraocular lens power calculation formulas

Background: To evaluate the accuracy of predicted refraction using multifocal intraocular lenses (IOLs) with power calculation based on two biometric devices and multiple IOL power calculation formulas. Design: A retrospective study conducted in a private practice ophthalmology clinic. Participants: Seventy-three eyes of 48 patients were evaluated. Methods: Consecutive cases of eyes that had undergone successful cataract surgery with an implantation of a multifocal IOL (SN6AD1, Alcon Laboratories, Inc., Fort Worth, TX, USA) by a single surgeon were enrolled. Patients were meticulously screened for suitability for a multifocal IOL implantation according to our clinic guidelines. Two biometric measurement devices (IOLMaster-500 [Carl Zeiss Meditec AG, Jena, Germany] and Lenstar-LS900 [Haag-Streit AG, Koeniz, Switzerland]) were used under strict validation criteria to evaluate the predicted refraction errors for the Holladay 1, SRK/T, Hoffer Q, Haigis, Holladay 2, Barrett Universal II and Olsen formulas. Main Outcome Measures: Predicted refractive sphere equivalent (RSE) errors. Results: The measurements obtained from the two biometric devices were highly correlated. The standard deviation of the error in predicted RSE and the median absolute error were similar for the IOLMaster and the Lenstar devices using all formulas, ranging from 0.27 dioptres (D) to 0.31D and from 0.15D to 0.21D, respectively. A high percentage of eyes had an error in predicted RSE within ±0.5D from target refraction, ranging from 86.3% to 93.2%. Conclusions: High accuracy can be achieved in multifocal IOL power calculations by appropriate patient selection, precise biometry and appropriate IOL calculation formulas.