Zhang Hongyuan, Roozbahani Mehdi, Piccinini Andre L, Hafezi Farhad, Scarcelli Giuliano, Randleman J Bradley
From the Cole Eye Institute, Cleveland Clinic (Zhang, Randleman), Cleveland, Ohio, Keck School of Medicine of the University of Southern California (Roozbahani, Piccinini, Hafezi) Los Angeles, California, USA; Sadalla Amin Ghanem Eye Hospital (Piccinini), Joinville, SC, Brazil; ELZA Institute (Hafezi), Ocular Cell Biology Group, University of Zurich (Hafezi), Zurich, Switzerland; University of Wenzhou (Hafezi), Wenzhou, China; and the Fischell Department of Bioengineering, University of Maryland (Scarcelli), College Park, Maryland, USA.
J Cataract Refract Surg. 2020 Nov;46(11):1543-1547. doi: 10.1097/j.jcrs.0000000000000294.
To determine the impact of corneal crosslinking (CXL) performed over the laser in situ keratomileusis (LASIK) flap using the Standard CXL (S-CXL) protocol or under the flap after flap lift (flap-CXL) on regional corneal stiffness using Brillouin microscopy.
University of Southern California Keck School of Medicine, Los Angeles, California, and Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, USA.
Laboratory ex vivo experiment.
After epithelium debridement, LASIK flaps were created on intact fresh porcine eyes with a mechanical microkeratome. Then, S-CXL (riboflavin applied to the corneal surface followed by 3 mW/cm ultraviolet exposure with the flap in place for 30 minutes) or flap-CXL (riboflavin applied to the stromal bed after reflecting the flap followed by the same ultraviolet A exposure with the flap replaced) was performed. Depth profile of stiffness variation and averaged elastic modulus of anterior, middle, and posterior stroma were determined by analyzing Brillouin maps. Each eye served as its own control.
The study was performed on 24 fresh porcine eyes. S-CXL had maximal stiffening impact in the anterior most corneal stroma within the LASIK flap (8.40 ± 0.04 GHz), whereas flap-CXL had lower maximal stiffening impact (8.22 ± 0.03 GHz) (P < .001) that occurred 249 ± 34 μm under the corneal surface. S-CXL increased longitudinal modulus by 6.69% (anterior), 0.48% (middle), and -0.91% (posterior) as compared with flap-CXL, which increased longitudinal modulus by 3.43% (anterior, P < .001), 1.23% (middle, P < .1), and -0.78% (posterior, P = .68).
The S-CXL technique generated significantly greater stiffening effect in the anterior cornea than a modified protocol with riboflavin administration under the flap (flap-CXL). Minimal stiffening occurred in the middle or posterior cornea with either protocol.
使用标准角膜交联术（S-CXL）方案或在瓣掀起后瓣下进行角膜交联术（瓣下CXL），通过布里渊显微镜检查确定在准分子原位角膜磨镶术（LASIK）瓣上进行角膜交联术（CXL）对局部角膜硬度的影响。
美国加利福尼亚州洛杉矶市南加州大学凯克医学院以及美国俄亥俄州克利夫兰市克利夫兰诊所科尔眼科研究所。
实验室离体实验。
在完整的新鲜猪眼上用机械微型角膜刀制作LASIK瓣，去除上皮后，进行S-CXL（将核黄素应用于角膜表面，然后在瓣在位的情况下用3 mW/cm的紫外线照射30分钟）或瓣下CXL（在瓣翻转后将核黄素应用于基质床，然后在瓣复位的情况下进行相同的紫外线A照射）。通过分析布里渊图确定硬度变化的深度剖面以及前、中、后基质的平均弹性模量。每只眼睛作为自身对照。
对24只新鲜猪眼进行了研究。S-CXL在LASIK瓣内最前部的角膜基质中产生最大的硬化影响（8.40±0.04 GHz），而瓣下CXL产生的最大硬化影响较低（8.22±0.03 GHz）（P<.001），发生在角膜表面下249±34μm处。与瓣下CXL相比，S-CXL使纵向模量增加了6.69%（前部）、0.48%（中部）和-0.91%（后部），瓣下CXL使纵向模量增加了3.43%（前部,P<.001）、1.23%（中部,P<.1）和-0.78%（后部,P=.68）。
与在瓣下给予核黄素的改良方案（瓣下CXL）相比，S-CXL技术在前部角膜产生的硬化效果明显更大。两种方案在中部或后部角膜产生的硬化作用最小。
