Abstract: Objective To compare the refraction effects of the implantation of the aspheric diffractive multifocal intraocular lens (IOL) with the Lenstar LS900 surgical guidance system to the traditional oprerations without the guidance system. Design Retrospective case series. Participants 36 patients (45 eyes) with senile cataract that underwent phacoemulsification and aspheric diffractive multifocal IOL implantation in Beijing Tongren  Hospital in Aug. 2013 were included. Methods 36 patients (45 eyes) were divided into two groups. Guidance group, include 17 patients (22 eyes), the sugeries of phacoemulsification and aspheric diffractive multifocal IOL implantation of whom were performed with the assistance of Lenstar LS900 surgery guidance system, the refraction parameters (axial length, anterior chamber depth, corneal curvature and astigmatism) of whom were measured with Lenstar LS900 and IOL Master independently before the operation, and the same parameters of whom were measured with Lenstar LS900 at 1 and 3 months after the operation. The control group, include 19 patients (23 eyes), the same parameters of whom were measured with IOL Master pre- and 3 months post-operation, and the sugeries of whom were performed without the assistance of the surgery guidance system. The parameters measured with Lenstar LS900 were compared to those measured with IOL Master in the guidance group at preoperation. The difference of astigmatism degrees between pre- and post-operation were compared between the two groups. Main Outcome Measures Axial length, anterior chamber depth, corneal curvature, and astigmatism. Results The mean axial length, corneal curvature, astigmatism diopter measured with Lenstar LS900 were not signifigantly different from the measurements with IOL Master (all P>0.05), and the mean anterior chamber depth was (2.82±0.46) mm with Lenstar LS900 and (3.14±0.52) mm with IOL Master (P=0.036). In the guidance group, the mean axial length was (25.48±3.26) mm at pre-operation, (25.38±3.01) mm at 1 month post-operation, and (25.40±3.01) mm at 3 months post-operation (P=1.000); the mean anterior chamber depth was (3.14±0.53) mm at pre-operation, (3.56±0.76) mm at 1 month post-operation, and (3.62±0.81) mm at 3 months post-operation (P=0.000); the mean astigmatism diopter was (0.97±0.37) D at pre-operation, (0.72±0.32) D at 1 month post-operation, and  (0.62±0.27) D at 3 months post-operation (P=0.003). The difference of astigmatism diopter between pre- and 3 months post-operation was (-0.35±0.27) D in guidance group, and (0.20±0.49)D in control group (P=0.000). Conclusion Real-time eye tracking based on Lenstar LS900 surgery guidance system can decrease the postoperative astigmatism diopter, thus increase the repeatability and accuracy of the surgery. It could be widely used in clinical practices.

Key words: phacoemulsification, surgery guidance system, ocular biological measurement, intraocular lens, , multifocal