Four-year visual outcomes and optical quality of SMILE and implantable collamer lens V4c (EVO-ICL) implantation for high myopia: a retrospective study

Background: To compare the 4-year visual outcomes of implantable collamer lens V4c (EVO-ICL) implantation and small incision lenticule extraction (SMILE) for high myopia and astigmatism. Methods: : This retrospective case study included 64 eyes of 40 patients. These patients with preoperative manifest refraction spherical equivalent (SE) between -6.00 and -10.00 diopters (D) were screened from the database of SMILE and EVO-ICL implantation procedures in 2015. The ICL group [32 eyes of 19 patients (mean age, 29.6±6.3 years); mean SE, -8.71±1.06 D] and SMILE group [32 eyes of 21 patients (mean age, 27.7±5.6 years); mean SE, -8.35±0.65D] were compared. All patients were then prospectively examined at a four-year follow-up for routine postoperative examinations, higher-order ocular aberrations, retinal image quality and a questionnaire. Results: : The safety indexes were 1.15±0.14 and 1.22±0.21 (P=0.36) for the SMILE and ICL groups, respectively. No eyes lost two or more lines of CDVA in either group. The efficacy indexes were 0.97±0.16 and 0.96±0.19 (P=0.87), respectively. Twenty-three eyes (72%) in ICL and 26 eyes (81%) in SMILE groups were within ±0.5 D of the attempted SE (P<0.01). ICL-treated eyes had significantly less spherical aberration and coma (P<0.01 and <0.05, respectively) postoperatively. Halos were the prevalent visual disturbance in both groups. Conclusion: SMILE and EVO-ICL implantation provided safe and effective correction of high myopia. SMILE showed slightly better long-term predictability. Mild postoperative visual disturbances were observed after ICL and SMILE at 4-year follow-up.