Comparison Of The Achieved Parameters And Intended Values After Small Incision Lenticule Extraction

Objective:To evaluate the accuracy of postoperative parameters of small incision lenticule extraction (SMILE) by comparing the achieved parameters with the intended values.Methods:This was a prospective clinical noncontrolled study.110eyes of57cases were treated with SMILE. The lenticule thickness and the optical zone diameter were measured using Orbscan Ⅱ system.Meanwhile, Visante optical coherence tomography was used to measure the thickness of cap and residual stromal bed. Datas were analyzed using paired-samples t test, Pearson correlation analysis and Bland-Altman agreement analysis.Results:The mean achieved lenticule thickness was103.5±20.2μm,5.2±9.9μm thicker than the intended mean value(p<0.001), which was98.3±18.6μm. Significant correlation between these two values (r=0.872, p<0.001) was found. The mean achieved lenticule thickness also had a good consistency with the expected value. The mean achieved optical zone diameter was6.37±0.25mm, which showed no significant difference with the intended lenticule diameter (6.40±0.21mm, p=0.465). The correlation and agreement were high between these two values. The cap thickness measured with Visante OCT was124.7±5.0μm, thicker than the programmed120μm (p<0.001), and good agreement existed between these two values. The mean achieved residual stromal bed thickness at the corneal apex was329.7±24.1μm, and the intended value was328.9±25.6μm. The difference was not statistically significant (p=0.344). They showed high correlation (r=0.976, p<0.001) and consistency.Conclusion:The achieved lenticule thickness was5.2μm thicker than the VisuMax readout lenticule depth, and measured cap thickness was4.7μm thicker than the intended value. All the achieved parameters had high consistency with the intended values.