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

项目摘要/摘要 这项提议的主要目的是检验这样一种假设，即非核黄素的光活化 利用飞秒激光的线性光学(NLO)、双光子过程(TP)的空间诱导 溶解(X-Y-Z)胶原交联物(CXL)和活体兔眼的机械硬化。 最近的研究证实，核黄素在370 nm光(UVA)下的光活化会导致 自由基诱导的胶原CXL的产生和角膜僵硬，显示出显著的治疗作用 对圆锥角膜患者的好处。虽然UVA和核黄素本身是无毒的，但 UVA准直光路内产生的自由基可导致细胞损伤，影响 角膜内皮和晶体蛋白晶状体，导致大泡性角膜病变和潜在的白内障。为了避免这种情况 并发症，治疗性给药UVA CXL已被滴定，以限制自由基的产生 角膜前部，从而降低CXL的疗效，并将治疗范围限制在受影响的患者 角膜厚度大于400？m。我们建议用近红外FS取代准直UVA光 激光在由聚焦确定的空间分辨焦体积内诱导NLO CXL 镜片将极大地提高CXL的安全性和有效性。与NLO CXL相比，它的主要优势 传统的UVA CXL包括：1)扩大角膜CXL在治疗稀释剂中的应用 扩张性角膜(&lt；400？m)，包括LASIK术后扩张症患者和目前的其他角膜疾病 建议用于常规UVA CXL，包括大疱性角膜病变、角膜溃疡和微生物感染； 2)前间质以外的附加治疗区域，包括中层、后层和全层 角膜基质；以及3)扩大使用由低紫外线激活的替代光敏剂(UVB和 紫外光(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。 为了验证这一假设，我们提出了以下具体目标：1)使当前的FS递送系统适用于现场 兔角膜NLO CXL，2)不同TP焦点体积、FS激光功率和扫描的影响 NLO CXL角膜硬化的速度，3)确定NLO CXL的短期影响(1天和3天) 与UVA CXL相比，角膜CAF、3D角膜弹性模数和细胞损伤，4)决定了长期 NLO CXL对角膜CAF、3D角膜弹性模数和细胞修复的影响(1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.