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Chemo-mechanical modification of the corneal response to photokeratectomy.

机译:对角膜切除术的角膜反应的化学机械修饰。

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摘要

Unintended anterior corneal flattening is a poorly understood complication of excimer laser phototherapeutic keratectomy (PTX) that pervades clinical practice despite efforts to remove a geometrically neutral lenticule of tissue during ablation. This document describes investigations into a model of keratectomy-induced curvature change in which intraoperative thickening of the stroma peripheral to the ablation zone is implicated as a mechanical stimulus for flattening of the central cornea. A paired-control human donor eye study was conducted to assess the efficacy of preoperative topical glutaraldehyde (GTA) treatment as a technique for inhibiting PTK-induced peripheral stromal thickening and, secondarily, for attenuating the acute corneal flattening response.; Twenty whole globes acquired in same-donor pairs were individually mounted in a custom holder, inflated to normal intraocular pressure (15 mmHg) and deepithelialized. According to a crosslinking protocol developed in preliminary experiments, one cornea of a given donor pair was immersed in a 15% dextran solution for 40 minutes then transferred to 4% GTA/dextran for an additional 20 minutes; the fellow control was exposed to 15% dextran for 60 minutes. Each eye was subsequently subjected to (1) sham PTK, a same-eye control phase incorporated to account for thinning due to intraoperative dehydration, (2) PTK(5-mm-diameter, 100-um-depth) and (3) a 1-hour hypo-osmotic soak phase designed to assess the anti-swelling activity of stromal crosslinking. A scanning-slit topography system was used to acquire triplicate thickness and curvature measurements before and after each experimental phase.; Crosslinking significantly inhibited peripheral stromal thickening during PTK and postoperative hypo-osmotic immersion. In addition, during PTK, crosslinked corneas demonstrated 36% less hyperopic shift relative to paired controls (p =.001). The magnitude of this latter effect was linearly dependent upon the magnitude of crosslink-mediated suppression of the peripheral thickening response to PTK (r = 0.68, p =.03). The results demonstrate that acute hyperopic shifts in a donor model of PTK can be significantly reduced through preoperative application of a collagen crosslinking reagent and therefore support the conclusion that mechanical events in the corneal periphery play an important role in keratectomy-induced central cunrature changes. This mechanism of curvature change is not accounted for in current surgical algorithms.
机译:意外的角膜前缘扁平化是准分子激光光疗性角膜切除术(PTX)的一个鲜为人知的并发症,尽管在消融过程中努力去除组织的几何中性小球,但这种现象仍普遍存在于临床实践中。该文献描述了对角膜切除术引起的曲率变化的模型的研究,其中在消融区域周围的间质的术中增厚被认为是使中央角膜变平的机械刺激。进行了配对对照的人类供体眼睛研究,以评估术前局部戊二醛(GTA)治疗作为抑制PTK诱导的外周基质增厚以及其次减轻急性角膜扁平化反应的技术的功效。在同一个供体对中采集的二十个全球分别安装在定制的支架中,充气至正常眼内压(15 mmHg)并进行深度鞘化。根据初步实验中开发的交联规程,将给定供体对的一个角膜浸入15%葡聚糖溶液中40分钟,然后再转移到4%GTA /葡聚糖中20分钟。另一个对照暴露于15%的葡聚糖中60分钟。随后对每只眼睛进行(1)假PTK,即同一眼控制阶段,以弥补术中脱水引起的变细;(2)PTK(直径5毫米,深度100um),(3) 1小时低渗浸泡阶段,旨在评估基质交联的抗溶胀活性。在每个实验阶段之前和之后,均使用扫描狭缝形貌地形测量系统获取一式三份的厚度和曲率测量值。交联显着抑制了PTK和术后低渗浸没过程中外周基质的增厚。此外,在PTK期间,交联的角膜的远视位移相对于配对对照降低了36%(p = .001)。后一种效应的大小与交联介导的对PTK的外周增厚反应的抑制作用的大小线性相关(r = 0.68,p = .03)。结果表明,PTK供体模型中的急性远视移位可通过术前应用胶原交联剂来显着降低,因此支持以下结论:角膜周围的机械事件在角膜切除术引起的中央性角膜变化中起重要作用。当前的外科手术算法中没有考虑这种曲率变化的机制。

著录项

  • 作者

    Dupps, William Joseph, Jr.;

  • 作者单位

    The Ohio State University.;

  • 授予单位 The Ohio State University.;
  • 学科 Health Sciences Ophthalmology.; Engineering Biomedical.; Health Sciences Medicine and Surgery.
  • 学位 Ph.D.
  • 年度 1998
  • 页码 99 p.
  • 总页数 99
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 生物医学工程;
  • 关键词

  • 入库时间 2022-08-17 11:48:41

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