Bertagno R, Giordano G, Murialdo U, Moreschalchi F, Di Lorenzo G, Venzano D, Traverso C E
University Eye Clinic of Genova, Italy.
Int Ophthalmol. 1994;18(3):159-61. doi: 10.1007/BF00915965.
The purpose of this study was to verify the feasibility of ab externo layer-by-layer excimer laser photoablative removal of limbal tissue down to the trabecular meshwork and to assess the damage caused by this procedure to the neighbouring structures. Excimer laser photoablation (193 nm) can remove layers of corneal tissue effectively with little or no damage to the adjacent areas. Previous experimental studies have demonstrated a decrease in outflow resistance after ab-externo photoablative removal of juxtacanalicular tissue. We have performed ab-externo photoablative removal of limbal tissue overlying the trabecular meshwork in four freshly enucleated eyes from our Eye Bank. The beam of an excimer laser (wavelength 193 nm; fluence 180 mJ/Sq.cm) was shaped using a metal mask with a rectangular opening of 1.2 x 2.5 mm. After removing the conjunctiva, photoablation was carried out at maximum surgical microscope magnification (40 x) until trabecular meshwork appeared at the bottom of the crater. Light microscopy showed that craters had smooth walls and their base reached the Schlemm's canal area; all structures appeared of normal morphology. Transmission electron microscopy showed a thin layer of amorphous material or pseudomembrane on the side walls of the crater; corneoscleral collagen fibers were abruptly interrupted and undistorted. At the bottom of the crater the trabecular meshwork and Schlemm's canal tissues appeared normal.
本研究的目的是验证从眼外逐层用准分子激光光消融去除角膜缘组织直至小梁网的可行性，并评估该手术对邻近结构造成的损伤。准分子激光光消融（193nm）能够有效去除角膜组织层，对相邻区域几乎没有或没有损伤。先前的实验研究表明，从眼外进行光消融去除近管组织后，流出阻力降低。我们对从眼库获取的4只新鲜摘除的眼球进行了眼外光消融，去除小梁网上方的角膜缘组织。使用带有1.2×2.5mm矩形开口的金属掩膜对准分子激光束（波长193nm；能量密度180mJ/平方厘米）进行塑形。去除结膜后，在手术显微镜最大放大倍数（40倍）下进行光消融，直至小梁网出现在凹坑底部。光学显微镜显示凹坑壁光滑，其底部到达施莱姆管区域；所有结构形态正常。透射电子显微镜显示凹坑侧壁有一层薄的无定形物质或假膜；角膜巩膜胶原纤维突然中断但未变形。在凹坑底部，小梁网和施莱姆管组织看起来正常。
