同步加速角膜胶原交联联合角膜激光屈光手术的研究进展：LASIK Xtra与SMILE Xtra

Research Advances in Simultaneous Accelerated Corneal Collagen Cross-Linking Combined with Corneal Laser Refractive Surgery: LASIK Xtra and SMILE Xtra

摘要: 同步加速角膜胶原交联也就是CXL与LASIK/SMILE同期联合，即Xtra，主要应用于高风险或者“边界风险”人群，来降低术后角膜生物力学不稳定以及扩张的风险。基于对26篇相关文献的分析显示：高度近视LASIK的随机对照或者同体对照研究(随访时间为12到24个月)，在屈光预测性或者稳定性方面，并未显示出持续且一致的获益；以生物力学指标作为主要终点的研究，同样没有证实其有明确且可测的“加固”效应。SMILE Xtra在1年随访时的总体屈光和视力结局良好，但部分研究报告其术后早期视力恢复稍慢。一项观察性队列研究显示：在“边界风险”亚组中，术后扩张只发生在未进行预防性CXL的SMILE眼，而接受SMILE Xtra的眼中没有出现扩张。然而，该发现受限于研究设计和相对较短的随访时间。在安全性方面，需要关注界面产生雾状混浊或浸润等炎症改变，强调严格区分无菌性与感染性病变并规范处理。总而言之，现有证据尚不足以支持在低风险人群中常规实施Xtra，把它作为特定高风险情境下的个体化风险缓释策略或许更为适宜。但仍有赖于更高质量、长期随访的研究来进一步验证。

Abstract: Simultaneous accelerated corneal collagen cross-linking (CXL) with LASIK/SMILE, referred to as Xtra, is primarily applied in high-risk or “borderline risk” populations to reduce the risk of postoperative corneal biomechanical instability and ectasia. An analysis of 26 relevant studies shows that randomized controlled or within-subject controlled studies on high myopia LASIK (with follow-up periods of 12~24 months) have not demonstrated consistent and sustained benefits in terms of refractive predictability or stability. Studies with biomechanical endpoints have similarly failed to demonstrate clear and measurable “reinforcement” effects. SMILE Xtra showed favorable refractive and visual outcomes at one-year follow-up, though some studies reported slightly slower early visual recovery postoperatively. An observational cohort study revealed that in the “borderline risk” subgroup, postoperative ectasia occurred only in SMILE eyes that did not receive prophylactic CXL, while no ectasia was observed in eyes that underwent SMILE Xtra. However, this finding is limited by study design and the relatively short follow-up duration. Regarding safety, attention is required for interface haze or infiltrative inflammatory changes, with a strong emphasis on distinguishing between sterile and infectious lesions and appropriate management. In conclusion, the existing evidence is insufficient to support the routine implementation of Xtra in low-risk populations. It may be more appropriate as an individualized risk-mitigation strategy in specific high-risk scenarios. Further high-quality, long-term follow-up studies are needed for confirmation.