Accuracy of toric intraocular lens alignment and predicted residual astigmatism using a 3D computer-guided visualization system in femtosecond laser-assisted cataract surgery

Abstract

Purpose: To evaluate the accuracy of toric intraocular lens alignment and predicted residual astigmatism in femtosecond laser-assisted cataract surgery using a 3D computer-guided visualization system

Methods: In this prospective cohort study, one eye of each patient receiving a toric intraocular lens (IOL) and femtosecond laser cataract surgery was enrolled. Four anterior segment surgeons at a single academic center performed all surgeries. Preoperatively, all patients received corneal topography measurements by the Lenstar, Galilei, and Cassini devices. The 3D computer-guided visualization system used keratometry values measured by the Cassini to create an optimized plan for the main incision location, toric IOL alignment, and predicted residual astigmatism. The IOL model was chosen by the surgeon based on the Baylor toric nomogram. The Catalys (AMO) femtosecond laser was used for capsulectomy and nuclear fragmentation. Additionally, two intrastromal marks were created by the femtosecond laser at the intended toric meridian using manual ink marks as a guide. Intraoperatively, the 3D system was used to guide placement of the main incision and align the toric IOL. The position of the femtosecond marks relative to the IOL axis was noted intraoperatively. At three weeks postoperatively, patients received corneal topography scans with the same devices. The position of the toric IOL and the femtosecond marks were noted at slit lamp examination. The manifest refraction and corrected distance visual acuity were also measured.

Results: The study will enroll 50 patients. Preoperatively and intraoperatively (n=13), our preliminary results found that the mean predicted residual astigmatism was -0.29 ± 0.24 D [-0.61 to 0.20], and the mean difference between the femtosecond mark and the toric IOL meridians was 1.30 ± 1.84 degrees [0 to 5]. Postoperative results (n=4) showed that the mean residual astigmatism was 0.44 ± 0.31 D [0 to 0.75]. The mean error in the 3D computer-guidedance system was 3.50 ± 1.91 degrees [1 to 5]. The mean IOL rotation postoperatively was 0.75 ± 0.96 degrees [0 to 2]. In all patients (n=4), the CDVA was 20/25 or better.

Conclusions: Additional patients are currently being enrolled and final results and conclusions will be presented. The performance of the 3D computer-guided visualization system will be discussed.