To evaluate the differences between the predicted and achieved lenticule thickness (ΔLT) after small incision lenticule extraction (SMILE) surgery and investigate relationships between ΔLT and predicted lenticule thickness in SMILE. A total of 184 eyes from 184 consecutive patients who underwent SMILE were included in this prospective study. One eye for each patient was randomly selected and included for statistical analysis. To achieve emmetropia, nomogram adds 10% correction of spherical refractive. An ultrasound pachymetry measurement and Scheimpflug camera corneal topography were obtained before and at 3 months after SMILE. The achieved lenticule thickness was calculated by comparing the preoperative examinations with postoperative examinations using ultrasound pachymetry and Pentacam software measurements. The pupil center and corneal vertex were selected as the 2 locations for measurement calculation on Pentacam. Analysis of variance (ANOVA) was performed to compare mean pachymetry values using different instruments. Linear regression analyses were performed between the VisuMax readout lenticule thicknesses and the measured maximum corneal change, between ΔLT and predicted lenticule thickness. On average, the achieved lenticule thickness measured with ultrasound pachymetry was 13.02 ± 8.87 μm thinner than the predicted lenticule thickness. The proportion of ΔLT in predicted values is 11.9% (ultrasound) and about 15% (Pentacam). Linear regression analysis showed significant relationships between the predicted and each achieved lenticule thickness. Each ΔLT was significantly related to predicted lenticule thickness (ultrasound: R2 = 0.242; pupil center from Pentacam: R2 = 0.230). An overestimation of achieved lenticule thickness was evident in this study which may exclude eligible SMILE patient. Also, our results showed that 10% increase of spherical refractive correction in the nomogram is appropriate. Furthermore, clinicians should subtract 10% of the predicted lenticule thickness to calculate the residual corneal stroma bed thickness.

中文翻译：

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小切口小孔镜摘除术中获得的小镜厚度的可预测性及其影响因素的研究

为了评估小切口小孔镜摘除术（SMILE）手术后的预计和达到的小镜厚度（ΔLT）之间的差异，并研究SLTLE中的ΔLT和预计的小镜厚度之间的关系。这项前瞻性研究包括来自184例接受SMILE的连续患者的184眼。为每位患者随机选择一只眼睛，并进行统计分析。为了实现正视，列线图添加了10％的球面屈光度校正。在SMILE之前和之后3个月获得超声测厚仪测量结果和Scheimpflug相机角膜地形图。通过比较术前检查与术后检查（使用超声测厚法和Pentacam软件测量）来计算获得的小透镜厚度。选择瞳孔中心和角膜顶点作为在Pentacam上进行测量计算的2个位置。使用不同的仪器进行方差分析（ANOVA）以比较平均测厚法值。在VisuMax读出的小透镜厚度和测得的最大角膜变化之间（在ΔLT和预测的小透镜厚度之间）进行线性回归分析。平均而言，通过超声测厚仪测得的达到的小透镜厚度比预测的小透镜厚度薄13.02±8.87μm。ΔLT在预测值中的比例为11.9％（超声波）和大约15％（Pentacam）。线性回归分析表明，预测的和每个达到的微透镜厚度之间存在显着的关系。每个ΔLT与预计的微透镜厚度显着相关（超声：R2 = 0.242；Pentacam的瞳孔中心：R2 = 0.230）。在这项研究中明显高估了达到的小孔厚度，这可能排除了合格的SMILE患者。同样，我们的结果表明，在诺模图中增加10％的球面折射校正是合适的。此外，临床医生应减去预计的小透镜厚度的10％，以计算残留的角膜基质床厚度。