Møller-Pedersen T, Cavanagh H D, Petroll W M, Jester J V
Department of Ophthalmology, Aarhus University Hospital, Denmark.
Cornea. 1998 Nov;17(6):627-39. doi: 10.1097/00003226-199811000-00011.
To determine whether excimer laser transepithelial photoablation can reduce the initial keratocyte loss seen after manual epithelial debridement. Second, to establish the relationship between initial depth of keratocyte and stromal loss and the subsequent development of corneal haze.
Five rabbits received a 5-mm diameter monocular epithelial debridement by manual scraping. An additional five rabbits received a 5-mm diameter excimer laser transepithelial photoablation to a preset (intended) depth of 60 microns to ensure complete epithelial removal and to generate a superficial stromal keratectomy in all corneas. At various times during a 3-month. period, animals were evaluated by in vivo confocal microscopy through focusing (CMTF), which generates a quantitative image intensity depth profile of the cornea that provides measurements of (i) depth of keratocyte loss, (ii) epithelial and stromal thickness, and (iii) backscattered light from the anterior cornea as an objective estimate of corneal haze.
Manual epithelial debridement was associated with an initial loss of anterior stromal keratocytes to a depth of 108 +/- 14 microns that was followed by repopulation with migratory keratocytes. These cells showed increased reflectivity producing significant backscattering of light equivalent to clinical haze grade 1-2 (1,442 +/- 630 U) at 3 weeks. Furthermore, repopulation occurred without detectable inflammation and was associated with a rapid restoration of normal keratocyte morphology and reflectivity. Transepithelial photoablation induced complete epithelial debridement in all corneas in addition to a superficial stromal keratectomy of 14-44 microns. Photoablation induced 36% less initial keratocyte loss (69 +/- 19 microns) in the anterior stroma than manual debridement (p < 0.01) but was associated with intense concomitant inflammation. Photoablated corneas showed significantly more light backscattering (p < 0.01) compared with manually debrided corneas with a threefold increase at 3 weeks (4,397 +/- 1,367 U) and a sixfold increase at 3 months (1,483 +/- 1,172 compared with 234 +/- 91 U). Backscattering of light or haze increased proportionally with increasing stromal keratectomy depth (r = 0.95, p < 0.001) but was unrelated to depth of induced keratocyte death. The increased backscatter in photoablated corneas appeared related to (i) a more pronounced keratocyte repopulation response with a higher density and reflectivity of migratory fibroblasts and (ii) myofibroblast transformation after repopulation.
Excimer laser transepithelial photoablation induced significantly less keratocyte loss than manual epithelial debridement; however, photoablation was followed by a more intense inflammatory response and a greater increase in backscattering of light (haze) that was associated with increased keratocyte activation and myofibroblast transformation. Most important, the magnitude of corneal wound repair and the development and duration of corneal haze increased proportionally with increasing stromal photoablation depth (i.e., the volume of stromal tissue removal) but were unrelated to depth of initial keratocyte loss.
确定准分子激光经上皮光消融术是否能减少手动上皮清创术后最初出现的角膜细胞损失。其次，确定角膜细胞和基质损失的初始深度与随后角膜 haze 形成之间的关系。
5 只兔子接受单眼手动刮除直径 5 毫米的上皮清创术。另外 5 只兔子接受直径 5 毫米的准分子激光经上皮光消融术，达到预设（预期）深度 60 微米，以确保完全去除上皮，并在所有角膜中形成浅层基质角膜切除术。在 3 个月期间的不同时间，通过聚焦式活体共聚焦显微镜（CMTF）对动物进行评估，该显微镜可生成角膜的定量图像强度深度剖面图，提供以下测量结果：（i）角膜细胞损失深度，（ii）上皮和基质厚度，以及（iii）来自角膜前部的后向散射光，作为角膜 haze 的客观估计值。
手动上皮清创术导致前部基质角膜细胞最初损失至 108±14 微米深度，随后有迁移性角膜细胞重新填充。这些细胞显示出反射率增加，在 3 周时产生相当于临床 haze 1 - 2 级（1442±630 U）的显著光后向散射。此外，重新填充过程中未检测到炎症，且与角膜细胞正常形态和反射率的快速恢复相关。经上皮光消融术除了在所有角膜中形成
