Non-linear Optical Collagen Cross-linking (NLO CXL) for Treatment of Keratoconus.

项目概要/摘要 该提案的主要目的是检验非光活化核黄素的假设， 线性光学（NLO），使用飞秒激光（FS）光空间诱导的双光子过程（TP 解决（X-Y-Z）胶原蛋白交联（CXL）和完整活兔眼的机械硬化问题。 最近的研究已经确定，370 nm光（UVA）对核黄素的光活化导致核黄素的光致降解。 产生自由基诱导的胶原蛋白CXL和角膜硬化，显示出显著的治疗效果 对患有圆锥角膜的患者有好处。虽然UVA和核黄素本身是无毒的， UVA准直光路内自由基的产生可导致细胞损伤， 角膜内皮和晶体蛋白透镜，导致大泡性角膜病变和潜在的白内障。为了避免这种 并发症，UVA CXL的治疗性给药已经滴定，以限制自由基的产生， 前角膜，从而降低了CXL的疗效，并限制了受影响患者的治疗范围。 角膜厚度超过400微米。我们建议用近红外FS代替准直UVA光 在由聚焦确定的空间分辨聚焦体积内诱导NLO CXL的激光 镜片将大大提高CXL的安全性和有效性。NLO CXL与 传统的UVA CXL将包括：1）将角膜CXL的应用扩展到治疗稀释剂 角膜扩张（<400 μ m），包括LASIK术后角膜扩张患者和目前的其他角膜疾病 建议用于常规UVA CXL，包括大泡性角膜病变、角膜溃疡和微生物感染; 2)前基质以外的其他治疗区域，包括中层、后层和全层 角膜基质;和3）扩大使用由低紫外线（UVB和 UVC）和可见光（400至780 nm），其使用单光子方法对视网膜具有光毒性。 为了验证这一假设，我们提出了以下具体目标：1）适应目前的FS交付系统， 兔角膜NLO CXL，2）确定改变TP焦点体积、FS激光功率和扫描的效果 3）确定NLO CXL对角膜硬化的短期影响（1天和3天）， 角膜CAF、3D角膜弹性模量和与UVA CXL相比的细胞损伤，4）确定长期 NLO CXL对角膜CAF、3D角膜弹性模量和细胞修复的影响（1个月和6个月）， UVA CXL。

Project Summary/Abstract The major objective of this proposal is to test the hypothesis that photoactivation of riboflavin by non- linear optical (NLO), two photon processes (TP) using femtosecond laser (FS) light induces spatially resolved (X-Y-Z) collagen cross-linking (CXL) and mechanical stiffening of intact, live rabbit eyes. Recent studies have established that photoactivation of riboflavin by 370 nm light (UVA) leads to the generation of free radical-induced collagen CXL and corneal stiffening that shows significant therapeutic benefits for patients suffering from Keratoconus. While UVA and riboflavin are themselves non-toxic, the generation of free radicals within the UVA collimated light path can lead to cellular damage affecting the corneal endothelium and crystallin lens, resulting in bullous keratopathy and potentially cataract. To avoid this complication, therapeutic administration of UVA CXL has been titrated to limit free radical generation to the anterior cornea, thus reducing the efficacy of CXL and limiting the therapeutic range to patients with affected corneas thicker than 400 ¿m. We propose that replacement of collimated UVA light with near-infrared FS laser light to induce NLO CXL within a spatially resolved focal volume determined by the focusing lenses would greatly improve the safety and efficacy of CXL. Major benefits of NLO CXL compared to conventional UVA CXL would included: 1) expanded application of corneal CXL to the treatment of thinner ectatic corneas (<400 ¿m) including post LASIK ectasia patients and other corneal disorders currently proposed for conventional UVA CXL including, bullous keratopathy, corneal ulceration and microbial infection; 2) additional treatment areas beyond that of the anterior stroma, including middle, posterior and full thickness corneal stroma; and 3) expanded use of alternative photosensitizers activated by low ultraviolet (UVB and UVC) and visible light (400 to 780 nm) that would be phototoxic to the retina using a single photon approach. To test this hypothesis we propose the following Specific Aims: 1) Adapt the current FS delivery system for live rabbit corneal NLO CXL, 2) Determine the effect of varying TP focal volume, FS laser power and scanning speed on NLO CXL corneal stiffening, 3) Determine the short-term affect (1 and 3 days) of NLO CXL on corneal CAF, 3D corneal elastic modulus, and cell damage compared to UVA CXL, 4) Determine the long-term affects (1 and 6 months) of NLO CXL on corneal CAF, 3D corneal elastic modulus, and cell repair compared to UVA CXL.