Clinical Evaluation of Toric Intraocular Lens Implantation Based on iTrace Wavefront Keratometric Astigmatism

Abstract

Background: There was no standard technique for measuring corneal astigmatism. The iTrace wavefront aberrometry of cornea calculated steep power and axis based on the best Zernike mathematical fit from all topo data within 4 mm circle. It was supposed to be more accurate than iTrace simulated keratometry which was calculated based on only 4 points on the circle of 3 mm. This study evaluated visual outcomes, rotational stability after performing toric intraocular lens (IOL) implantation planning based on the wavefront aberrometry of the cornea with iTrace. Setting: Single site in China, Shanxi Eye Hospital, Shanxi, China. Design: Prospective case series. Methods ： The study included 85 eyes of 63 patients undergoing phacoemulsification and toric IOL implantation. The IOL power and cylinders were chosen with the help of the iTrace toric planning program using wavefront keratometric astigmatism. Over a 3-month follow-up period, astigmatic changes were assessed using the Alpins vector method. Results ： Preoperative mean corneal topographic astigmatism was 1.91 diopters (D) ± 0.69 (standard deviation). Postoperative mean refractive astigmatism decreased significantly to 0.48 D ± 0.34. Surgical induced astigmatism was 1.73 D ± 0.77 and the mean correction index was 0.89 ± 0.22, showing a slight undercorrection. The proportion of astigmatism ≤ 0.50 D increased from 0 to 71.8% postoperatively. Conclusions ： This is the first study evaluating the clinical outcomes of using iTrace wavefront keratometric readings to plan a toric IOL implantation. The findings show that the iTrace built-in toric calculator with wavefront keratometric astigmatism for toric IOL planning is safe and effective.