Early clinical outcomes of small incision lenticule extraction for different refractive myopia and astigmatism

Background

Small incision lenticule extraction (SMILE) is increasingly applied in the correction of myopia and astigmatism.However, the early clinical outcomes of SMILE for different refractive myopia and astigmatism is seldom reported.

Objective

This study was to investigate the safety, efficacy, predictability and early stability after SMILE in low, moderate and high myopia.

Methods

A series of cases-observational study was carried out.A total of 195 eyes of 108 myopic patients were enrolled in Tianjin Eye Hospital from May to December 2012 under the informed consent.The patients were divided into the low (≤-3.00 D), moderate (>-3.00 to -6.00 D) and high myopia (>-6.00 D) groups according to different diopters, with 57 eyes, 76 eyes and 62 eyes, respectively.SMILE was performed on all the eyes.The uncorrected visual acuity (UCVA)(LogMAR), best corrected visual acuity (BCVA)(LogMAR), equivalent sphere (SE), intraocular pressure, anterior segment and corneal topography were examined before operation and 1 day, 1 week, 1 month and 3 months after operation to evaluate the effective index (postoperative UCVA/preoperative BCVA), safety index (postoperative BCVA/preoperative BCVA), predictability and early stability of SMILE.The linear regression analysis was used to analyze the relationships between the attempted refraction and the achieved refraction postoperative 3 months in three groups.

Results

The percentage of UCVA (LogMAR)<0.1 was 100%, 97.1% and 92.8% in the low, moderate and high myopia group, respectively in 3 months after SMILE.The postoperative BCVA of all the operated eyes reached preoperative one.The residual SE was (-0.07±0.16), (-0.05±0.20) and (-0.08±0.27)D in the low, moderate and high myopia group, respectively in 3 months after SMILE.The percentage of residual SE±0.5 D was 100%, 98.7% and 93.6% in the low, moderate and high group, and that of SE±1.0 D was 100% in all of the groups.The postoperative corrected SE was gradually increased with the raise of predicted SE in the low, moderate and high myopia groups (r=0.942, 0.959, 0.957, all at P<0.001).

Conclusions

SMILE is safe, effective, predictable and stable for the correction of low, moderate and high myopia.The corneal wound healing was slightly slower in the low myopia group than that in the moderate and high group.A slight regression of myopic power appears in high myopia eyes 3 months after SMILE.