Abstract
Purpose :
To determine corneal high order aberrations (HOAs) and asphericity (Q) values after SMILE at different stromal cap-depths of 100 um, 120um, 140um and 160um.
Methods :
A retrospective, observational, comparative study to assess corneal HOAs and asphericity values over time after SMILE in healthy patients with mild to high myopia who were screened for refractive surgery and fulfilled the safety criteria. Corneal HOAs and asphericity were measured by Scheimpflug Tomography with the Pentacam AXL (Oculus, Wetzlar, Germany) preoperatively and on days 1, 7, 30 and 90 postoperatively.
245 eyes of 125 patients were included and divided in four groups according to cap depth. 72, 79, 62, and 32 eyes were included in the 100, 120, 140 and 160 µm group respectively. Paired sample T-tests were performed to determine changes in corneal asphericity and HOAs for each group.
Results :
Mean patient age was 27.62±5.09 years, with most patients of female gender (74.9%). Spherical equivalent range went from -13.5 to -0.875. Mean maximum keratometry and minimum keratometry values were 42.62±1.5 and 44.72±1.72 respectively. Before surgery, mean corneal asphericity was -0.28±0.16, and HOA was 0.38±0.14.
Regarding corneal asphericity, statistically significant differences were found in all groups throughout follow-up visits (p<0.01), with increased values after surgical treatment (0.58±0.53) and changes until the 3-month visit (0.65±0.47), in which no significant differences were seen.
HOAs showed a statistically significant increase in all groups after surgery(0.97±0.46, p<0.01), however, in follow-up visits, each group behaved differently. In the 100 µm and 140 µm cap depth groups there were no further significant changes at any point after day 1. In the 120 µm group, a decrease in HOA is observed at week 1 (1.04±0.57, p=0.03) after which no further changes were seen. In the 160 µm group, there is a statistically significant decrease in HOAs in the 1 month follow-up visit (0.78±0.28, p=0.04), but HOAs increase again at the 3-month follow-up visit (0.88±0.32, p<0.01).
Conclusions :
Corneal asphericity stabilizes 3 months after SMILE; however, HOAs behavior differs; since stability over time is achieved in the postoperative period with a 100, 120 and 140 µm cap-depth; however with a 160 um cap-depth HOAs increases its value on the third month visit.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.