Refractive and visual outcomes of small incision lenticule extraction (SMILE) in eyes with thin corneas

Abstract

Objectives To report the refractive and visual outcomes of small incision lenticule extraction (SMILE) with the thinnest corneal thickness (CCT) of less than 500 mu m and evaluate it in terms of safety and efficacy. Setting Refractive Surgery Clinic of University of Health Sciences Beyoglu Eye Training and Research Hospital, Istanbul, Turkey. Design Retrospective case series. Methods The pre-and-postoperative examinations of all patients with thin corneas (preoperative CCT <500 mu m) who underwent the SMILE procedure and had a minimum of 24 months of follow-up records were reviewed from medical files. The main outcome measures of the refractive and visual outcomes and the effect on corneal high order aberrations (HOAs) were evaluated. Results The study included 55 eyes of 39 patients. The mean preoperative uncorrected visual acuity (UDVA) was 1.3 +/- 1.5 logMAR, and the mean postoperative UDVA was significantly improved to 0.05 +/- 0.80 logMAR at the last visit (p < 0.001). At the last follow-up, 84% of the eyes were within +/- 0.50D, and 96% of the eyes were within +/- 1.00D of attempted SE refraction. The HOAs of coma (p < 0.001), secondary astigmatism (p = 0.015), spherical aberration (p < 0.001), and RMS (p < 0.001) aberrations increased significantly from the baseline to the postoperative last visit. The increase in trefoil was not significant (p = 0.32). No sight threatening complications or ectasia were observed during the follow-up time. Conclusion SMILE is a safe and effective technique with long-term stability for treatment of myopia in eyes with a thin cornea, and satisfactory results can be obtained if candidates for surgery are selected carefully with particular emphasis on normal preoperative corneal topography.