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取新西兰白兔5只(10眼),先用角膜曲率仪测定角膜曲率和屈光度。然后刮去角膜中部上皮。用Er:YAG 激光照射角膜中部,能量密度1118—1240mJ/cm~2,脉宽150μs。照射的脉冲数按兔的序号1—5,分别为60,80,100,120,160。激光照射后4天—4个月用裂隙灯角膜显微镜观察角膜情况及检测角膜曲率和屈光度。术后4月作光镜及扫描电镜检查,并对内皮细胞作计算机图象定量分析测定。术后早期见角膜热损伤明显,至术后4月角膜基本恢复透明。经过激光消融角膜屈光度可下降2—8D。我们相信如果将脉宽缩短<1μs 的热扩散时间,并取消融阈值邻近的能量密度,可使热损伤明显减轻。
Five New Zealand white rabbits (10 eyes) were taken. The corneal curvature and refraction were measured by keratometer. Then scrape off the central corneal epithelium. Er: YAG laser irradiation of the central corneal energy density 1118-1240mJ / cm ~ 2, pulse width 150μs. Irradiated pulse number rabbit according to the serial number 1-5, respectively 60,80,100,120,160. Four days to four months after laser irradiation, the situation of the cornea was observed with a slit lamp corneal microscope and the corneal curvature and refraction were examined. After 4 months for light microscopy and scanning electron microscopy, and endothelial cells for computer image quantitative analysis. Early postoperative corneal heat injury was obvious, to the cornea after surgery basically returned to transparency. After laser ablation corneal refractive error can be reduced 2-8D. We believe that if the pulse width is shortened by a thermal diffusion time of <1 μs and the energy density adjacent to the threshold is abolished, thermal damage can be significantly reduced.