Detection of and Compensation for Static Cyclotorsion With an Image-Guided System in SMILE.

Abstract

To evaluate the effect of cyclotorsion compensation with an image-guided system (Callisto eye; Carl Zeiss Meditec AG, Jena, Germany) on the visual and refractive outcomes of small incision lenticule extraction (SMILE) surgery for astigmatism. The medical records of 124 right eyes of 124 patients with astigmatism of 0.75 diopters (D) or greater who underwent SMILE for myopic astigmatism were reviewed. Patients were treated with cyclotorsion compensated SMILE or standard SMILE. After the sitting position reference axis was registered with IOLMaster 700 (Carl Zeiss Meditec AG), these data were transferred to the Callisto eye system, which was connected to the operating VisuMax microscope (Carl Zeiss Meditec AG). Cyclotorsion was measured by activating the Z-align function and compensated for by repositioning the patient's body or tilting the head until the reference axis from the IOLMaster 700 (0-180) was parallel to a manually drawn reference axis on the screen (0-180) before docking. The visual and refractive results were studied preoperatively and postoperatively. Astigmatic changes were interpreted using the Alpins method. Six months after surgery, the results showed that the astigmatic eyes in the cyclotorsion compensated group had improved axial alignment, more precise astigmatic correction, and better postoperative uncorrected distance visual acuity (UDVA) compared with the standard group. The mean logMAR UDVA was 0.02 ± 0.10 (range: -0.15 to 0.30) and 0.06 ± 0.11 (range: -0.15 to 0.30) (P = .13) and the mean astigmatic error was -0.19 ± 0.17 D (range: -0.50 to 0.00 D) and -0.45 ± 0.38 D (range: -1.50 to 0.00 D) (P < .001) in the cyclotorsion compensated group and the standard group, respectively. In regard to vector analysis, the mean index of success was 0.00 ± 0.00 (range: 0.00 to 0.00) and 0.40 ± 0.48 (range: 0.00 to 2.72) (P < .001), and the mean absolute angle of error in degrees was 1.18 ± 2.23 (range: 0.00 to 13.00) and 3.76 ± 3.80 (range: 0.00 to 14.00) (P < .001) in the cyclotorsion compensated group and the standard group, respectively. The combination of the Callisto eye system with a VisuMax laser might be an efficacious and reliable approach to enhance astigmatism treatment with SMILE surgery. [J Refract Surg. 2020;36(3):142-149.].