Résumé
Small incision lenticule extraction (SMILE) is a new option for corneal refractive surgery,which has developed quickly in recent years.Although modern corneal refractive surgery has reached a high success rate,enhancement may be required after refractive surgery.Reasons for enhancement include initial overcorrection or undercor rection and refractive regression,corneal epithelium and stromal remodeling are two main factors contributing to refractive regression.The corneal remodeling process and the risk factors of enhancement after SMILE,and the potential enhancement strategies and their effects,and wound healing process and corneal biomechanics after enhancement are important issues in clinic.This article reviewed relevant literatures and focused on the above issues.
Résumé
PURPOSE: To compare preoperative and postoperative thickness and to investigate the difference in the thickness change of corneal epithelium and stroma after cataract surgery through scleral tunnel incision. METHODS: Forty eyes of forty patients who were 40 years old or older and underwent small-incision superior scleral tunnel cataract surgery with phacoemulsification were included. Using the RTVue instrument (Optovue Inc., Fremont, CA, USA), corneal epithelial (ET) and stromal thicknesses (ST) of all subjects were measured preoperatively and at 3 days, 1 week, and 1 month postoperatively. Thicknesses were classified into 3 zones according to the distance from the vertex: central zone (within 2 mm), paracentral zone (2-5 mm diameter) and midperipheral zone (5-6 mm diameter). RESULTS: Mean central ST was 486.68 ± 25.15 µm, 535.16 ± 48.13 µm, 515.98 ± 44.07 µm, and 502.28 ± 34.87 µm preoperatively, and at 3 days, 1 week, and 1 month postoperatively, respectively (p < 0.001 for all). ST showed significant thickening in all three zones from 3 days to 1 month postoperatively (p < 0.001 for all). Mean central, paracentral, and midperipheral ET was 52.13 ± 3.41 µm, 50.42 ± 2.97 µm, 49.12 ± 3.05 µm at preoperatively and 51.03 ± 3.63 µm, 48.96 ± 3.62 µm, 47.67 ± 3.81 µm at 1 month postoperatively, respectively (p = 0.061, 0.006, 0.001, respectively), while there were no signficant changes in all three zones at 3 and 7 days postoperatively. Changes in ET and ST were prominent at the superotemporal incision site. CONCLUSIONS: After scleral tunnel cataract surgery, corneal edema was observed in the stroma immediately after surgery. There was no significant change at early times after surgery in the epithelium, and there was a decrease in the peripheral cornea at 1 month postoperatively. The change in ET was considered a compensatory change due to stromal edema and appeared between 1 week to 1 month postoperatively.