O'Brart David P S
Department of Ophthalmology, Keratoconus Research Institute, St. Thomas' Hospital, London - UK.
Eur J Ophthalmol. 2017 May 11;27(3):253-269. doi: 10.5301/ejo.5000916. Epub 2016 Dec 6.
To review the published literature on corneal collagen crosslinking (CXL).
Importance has been placed on seminal publications, systemic reviews, meta-analyses, and randomized controlled clinical trials. Where such evidence was not available, cohort studies, case-controlled studies, and case series with follow-up greater than 12 months were examined.
Corneal collagen crosslinking with riboflavin and ultraviolet A (UVA) 370 nm radiation appears to be capable of arresting the progression of ectatic corneal disorders, with most studies reporting significant improvements in visual, keratometric, and topographic measurements. Its mode of action at the molecular level is undetermined. Follow-up is limited to 5-10 years but suggests sustained stability and enhancement in corneal shape with time. Nearly all published long-term data and comparative studies are with epithelium-off techniques. Epithelium-on investigations suggest some efficacy but less than with epithelium-off treatments and long-term data are unavailable. Accelerated techniques with higher UVA fluencies and shorter treatments times, delivering the same UVA energy dosage, are the subject of recent investigation, with some laboratory and clinical studies suggesting reduced efficacy compared to the standard 3 mW/cm2 for 30 minutes irradiation procedure. Combined methodologies of CXL with techniques such as photorefractive keratectomy and intrastromal rings show promise but long-term follow-up is indicated. Sight-threatening complications of CXL are rare.
Studies of epithelium-off CXL with irradiation at 3 mW/cm2 for 30 minutes support its efficacy. Refinement in techniques may allow for safer and more rapid procedures with less patient discomfort but require further investigation.
回顾已发表的关于角膜胶原交联（CXL）的文献。
重点关注开创性出版物、系统评价、荟萃分析和随机对照临床试验。若缺乏此类证据，则审查队列研究、病例对照研究以及随访时间超过12个月的病例系列。
核黄素联合370nm紫外线A（UVA）进行角膜胶原交联似乎能够阻止扩张性角膜疾病的进展，大多数研究报告在视力、角膜曲率测量和地形图测量方面有显著改善。其在分子水平的作用机制尚不清楚。随访时间限制在5至10年，但显示随着时间推移角膜形状持续稳定且有所改善。几乎所有已发表的长期数据和比较研究均采用去上皮技术。表面上皮完整的研究表明有一定疗效，但低于去上皮治疗，且缺乏长期数据。近期研究的主题是采用更高UVA通量和更短治疗时间的加速技术，在提供相同UVA能量剂量的情况下，一些实验室和临床研究表明与标准的3mW/cm²照射30分钟程序相比疗效降低。CXL与诸如准分子激光原位角膜磨镶术和角膜基质环等技术相结合的方法显示出前景，但需要长期随访。CXL导致视力威胁性并发症的情况罕见。
关于3mW/cm²照射30分钟的去上皮CXL研究支持其疗效。技术的改进可能会实现更安全、更快速的程序，减少患者不适，但仍需进一步研究。
