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激活核黄素的假设 线性光学 (NLO)、使用飞秒激光 (FS) 光进行空间感应的两个光子过程 (TP) 解析（X-Y-Z）胶原交联（CXL）和完整活兔眼的机械硬化。 最近的研究表明，370 nm 光 (UVA) 对核黄素的光活化会导致 产生自由基诱导的胶原蛋白 CXL 和角膜硬化，显示出显着的治疗作用 对圆锥角膜患者有好处。虽然 UVA 和核黄素本身无毒， UVA 准直光路内自由基的产生会导致细胞损伤，影响 角膜内皮和晶状体，导致大疱性角膜病和潜在的白内障。为了避免这种情况 并发症，UVA CXL 的治疗给药已被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 µm。我们建议用近红外 FS 代替准直 UVA 光 激光在由聚焦确定的空间分辨焦体积内诱导 NLO CXL 镜片将大大提高 CXL 的安全性和功效。与 NLO CXL 相比的主要优点 传统的UVA CXL将包括：1）扩大角膜CXL的应用以稀释剂的治疗 角膜扩张（<400 µm），包括 LASIK 术后角膜扩张患者和目前的其他角膜疾病 建议用于传统 UVA CXL，包括大疱性角膜病变、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； 3) 扩大使用低紫外线（UVB 和 UVB）激活的替代光敏剂 UVC）和可见光（400 至 780 nm），使用单光子方法会对视网膜产生光毒性。 为了检验这一假设，我们提出以下具体目标： 1) 调整当前的 FS 传输系统以实现实时直播 兔角膜 NLO CXL，2) 确定不同 TP 焦体积、FS 激光功率和扫描的效果 NLO CXL 角膜硬化的速度，3) 确定 NLO CXL 对 NLO CXL 的短期影响（1 和 3 天） 与 UVA CXL 相比的角膜 CAF、3D 角膜弹性模量和细胞损伤，4) 确定长期 与相比，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.