Visual Outcome with Irrigation of the Interface in Small-Incision Lenticule Extraction

Abstract

Purpose: To compare the refractive and visual outcomes after Small-Incision Lenticule Extraction (SMILE) in patients receiving irrigation of the stromal interface versus no irrigation in the United States based on FDA-approved parameters.Methods: In this US-based, single-center, consecutive, retrospective case series, patients undergoing SMILE received irrigation in one eye versus no irrigation in the other eye. Primary outcome measures included uncorrected visual acuity (UCVA) post-op day 1, post-op week 1, and post-op month 1, mean manifest refraction spherical equivalent (MRSE), and the number of patients within ±0.5 D and ±1.0 D of refractive target. Same-day post-op pachymetry and anterior-segment OCT were also obtained. Safety was assessed by noting the incidence of complications and need for additional surgery.Results: 32 patients were included in the study, with 32 eyes in both the irrigated and non-irrigated groups. All patients were targeted for plano refraction. UCVA on POM1 was 0.0038 ± 0.164 D for irrigated eyes and -0.0154 ± 0.141 D for non-irrigated eyes (P = 0.40). The MRSE on POM1 was -0.232 ± 0.483 D for irrigated eyes and -0.274 ± 0.539 D for non-irrigated eyes. In the irrigated eyes group on POM1, 21 of 21 patients were within ±1.0 D of refractive target compared to 18 of 21 in the non-irrigated group. Adjusting for expected pachymetry, irrigated eyes had an average of 15.406 ± 0.347 microns thicker post-operative pachymetry readings compared to the non-irrigated eyes (P = 0.006). Conclusion:Irrigated eyes had better UCVA, lower MRSE, and deviated less from their refractive target compared to non-irrigated eyes. Irrigated eyes had a significant increase in corneal pachymetry measured immediately postoperatively compared to non-irrigated eyes, however its effect on visual outcome was not significant.