Small incision lenticule extraction (SMILE) is an "all-in-one" surgical method for refractive correction. An advantage of the SMILE over traditional surgery is that it depends on the corneal cap’s design. This review discusses the morphological evaluation of the corneal cap, selection of the corneal cap with different thickness and diameters, influence of the corneal cap design on retreatment, and management of corneal cap-related complications. The following points should be recognized to define the correct morphology and design of the operation-related parameters of the corneal cap during SMILE: (1) the thickness and diameter of the corneal cap are predictable and influence postoperative visual quality, (2) the change in anterior surface curvature of the corneal cap should be considered in the design of nomogram value, (3) for patients with moderate myopic correction, early visual quality is better with a 6.9-mm than with a 7.5-mm diameter corneal cap, (4) there is no significant difference in visual quality or biomechanics among corneal caps with different thickness; (5) primary corneal cap thickness plays an important role in the SMILE retreatment, (6) a 7.78-mm diameter corneal cap has a greater risk of suction loss than a 7.60-mm diameter corneal cap, (6) if suction loss occurs when lenticular scanning exceeds 10%, then SMILE can be continued by changing corneal cap thickness, (7) preventive collagen cross-linking with SMILE caps are 90–120 μm thick and 7–7.8 mm in diameter, and (8) properly treating SMILE-related complications ensures better postoperative results. The data presented herein shall deepen the understanding of the importance of the corneal cap during SMILE and provide diversified analysis for personalized operational design of corneal cap parameters.


中文翻译：

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小切口微晶状体摘除角膜帽形态学变化及手术相关参数研究进展

小切口微透镜提取术 (SMILE) 是一种用于屈光矫正的“一体化”手术方法。与传统手术相比，SMILE 的一个优势在于它取决于角膜帽的设计。本综述讨论了角膜帽的形态学评估、不同厚度和直径的角膜帽的选择、角膜帽设计对再治疗的影响以及角膜帽相关并发症的处理。在 SMILE 期间定义正确的角膜帽形态和手术相关参数的设计应认识到以下几点：（1）角膜帽的厚度和直径是可预测的并影响术后视觉质量，（2）变化在设计列线图值时应考虑角膜帽的前表面曲率，(3)对于中度近视矫正患者，6.9-mm角膜帽的早期视觉质量优于7.5-mm直径的角膜帽，(4)不同厚度角膜帽的视觉质量或生物力学无显着差异；(5) 原发性角膜帽厚度在 SMILE 再治疗中起重要作用，(6) 7.78 毫米直径的角膜帽比 7.60 毫米直径的角膜帽有更大的吸力损失风险，(6) 如果在透镜扫描超过 10%，则可以通过改变角膜帽厚度来继续 SMILE，（7）与 SMILE 帽的预防性胶原交联厚度为 90-120 μm，直径为 7-7.8 mm，以及（8）正确处理 SMILE-相关并发症确保更好的术后效果。