Confocal microscopic characterization of wound repair after photorefractive keratectomy.
Confocal microscopic characterization of wound repair after photorefractive keratectomy.
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发表时间：
1998-03
影响因子：
4.4
通讯作者：
T. Møller-Pedersen;H. Li;W. Petroll;H. Cavanagh;James V. Jester;James V. Jester
中科院分区：
文献类型：
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作者：
T. Møller-Pedersen;H. Li;W. Petroll;H. Cavanagh;James V. Jester;James V. Jester
目的 准分子激光屈光性角膜切除术（PRK）术后出现角膜混浊和屈光效果退化是不利的临床并发症。尽管确切的机制仍有待阐明，但这些结果归因于 PRK 后角膜伤口愈合。本研究的目的是使用新开发的体内技术（称为聚焦共聚焦显微镜（CMTF））对兔模型中 PRK 后的角膜伤口修复进行定量评估。方法 12只兔子角膜接受单眼、直径6毫米、屈光度9.0的PRK近视矫正。术后 6 个月内通过体内 CMTF 对动物进行连续评估，该模型使用图像强度深度剖面来测量上皮和基质厚度，并使用角膜光反射率作为角膜雾度的客观估计。在不同的时间间隔，使用荧光显微镜将体内形态学与离体组织学相关联。结果 PRK 后一周，在剩余基质的前方发现了 86 +/- 24 微米的无细胞层，这表明手术诱导的角膜细胞死亡。下面的角膜细胞被激活并向伤口床迁移；重新填充在三周内完成。 PRK 一周后，从光消融基质表面 (1745 +/- 262 U) 和下面的活化成纤维细胞 (713 +/- 607 U) 检测到的光反射显着增加 (P < 0.001)。角膜反射率在 PRK 3 周时达到峰值 (4648 +/- 1263 U)，并在 PRK 后 6 个月线性下降至 889 +/- 700 U；这相当于未手术角膜反射率的六倍。 PRK 两周后，最初的角膜水肿已解决，显示实际消融深度（最大基质变薄）为 118 +/- 8 微米。术后2周开始，间质逐渐增厚，PRK后6个月达到术前厚度的98%；当时，仅保留了初始光消融深度的 6%。相比之下，术后中央角膜上皮未见明显增生。结论 经过 PRK 治疗的兔角膜显示出显着的基质伤口愈合反应，最终在术后 6 个月恢复了原始基质厚度，证明了初始光消融效果的完全消退。此外，角膜伤口愈合与光消融基质表面和该区域下方激活的伤口愈合角膜细胞的光反射增加有关。基于这些发现，作者推测，临床观察到的 PRK 患者角膜混浊的发展可能部分与角膜角膜细胞的激活和细胞外基质的假定变化有关。
PURPOSE Development of postoperative corneal haze and regression of refractive effect are unfavorable clinical complications of excimer laser photorefractive keratectomy (PRK). Although exact mechanisms remain to be elucidated, these outcomes have been attributed to post-PRK corneal wound healing. The purpose of this study was to evaluate corneal wound repair quantitatively after PRK in a rabbit model using a newly developed in vivo technique, termed confocal microscopy through focusing (CMTF). METHODS Twelve rabbit corneas received a monocular, 6-mm diameter, 9.0-diopter PRK myopic correction. Animals were evaluated sequentially up to 6 months after surgery by in vivo CMTF, which uses an image-intensity depth profile to measure epithelial and stromal thickness and uses corneal light reflectivity as an objective estimate of corneal haze. At differing temporal intervals, in vivo morphology was correlated with ex vivo histology using fluorescence microscopy. RESULTS One week after PRK, an acellular layer of 86 +/- 24 microns was found anteriorly in the remaining stroma, which demonstrated surgically induced keratocyte death. Underlying keratocytes became activated and migrated toward the wound bed; repopulation was completed within 3 weeks. One week after PRK, there was a significant increase (P < 0.001) in light reflections detected from the photoablated stromal surface (1745 +/- 262 U) and from the underlying activated fibroblasts (713 +/- 607 U). Corneal reflectivity peaked at 3 weeks (4648 +/- 1263 U) and decreased linearly to 889 +/- 700 U by 6 months after the PRK; this corresponded to a reflectivity six times greater than the level seen in unoperated corneas. Two weeks after PRK, initial corneal edema had resolved, revealing an actual ablation depth (maximal stromal thinning) of 118 +/- 8 microns. Starting at 2 weeks after surgery, the stroma underwent gradual rethickening that reached 98% of the preoperative thickness at 6 months after PRK; at that time, only 6% of the initial photoablation depth persisted. By contrast, the central corneal epithelium showed no significant postoperative hyperplasia. CONCLUSIONS Rabbit corneas treated by PRK showed a remarkable stromal wound-healing response that ultimately led to the restoration of the original stromal thickness by 6 months after surgery, demonstrating complete regression of the initial photoablative effect. Additionally, corneal wound healing was associated with increased light reflections from both the photoablated stromal surface and the activated wound-healing keratocytes underlying this area. Based on these findings, the authors hypothesize that the development of clinically observed corneal haze in PRK patients may be related, in part, to activation of corneal keratocytes and to putative changes in the extracellular matrix.