摘要
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。
The corneal curvature and refractivepower of five Newzeland white rabbits (10eyes) were measured by cornealrefractometer,and the central area cornealepithelium of these rabbits wer'e removed.Then the corneas were irradiated by Er:YAG laser with fluence 1118-1240mJ/cm2,pulse duration 150 us,and 6,80,100,120and 160 pulses on No.1-5 rabbitsrespectively.The corneas were observed byslit-lamp microscope after laser irradiation,and their curvature and refractive powerwere measured 4 days,12 days,3 weeks,1month,2 months,3 months and 4 monthspostoperatively.Both eyes of No.3,4,5rabbits were enucleated 4 monthspostoperatively,in which left eyes wereexamined by light microscope,and theendothelium of right eyes were observed byelectron scanning microscope and computerquantitative image analysis.The thermal damage of the corneas wassignificant in the early stagepostoperatively,but the corneas becamealmost clear 4 months postoperatively,andthe refractive power 2-8 D decreased.Webelieve that thermal damage will be reducedsignificantly if laser pulse duration isreduced to less than 1 us which is thethermal relaxation time with fluence of nearablation threshold.
