770～2500 nm超连续谱光源致兔角膜损伤研究

Rabbit Corneal Injury Induced by 770～2500 nm Supercontinuum Source

目的研究超连续谱(supercontinuum spectrum,SC)光源角膜损伤病理特点,确定损伤阈值。方法采用波长770~2 500 nm的SC光源,角膜光斑直径0.56 mm,照射新西兰白兔13只的角膜。按照射时间不同分为两个大组:A组,照射时间2 s;B组,照射时间10 s。A、B组再根据照射功率不同再分为4个小组:A1~A4组照射功率分别为1.24 W、1.15 W、1.07 W和1.00 W;B1~B4组照射功率分别为0.93 W、0.86 W、0.80 W和0.75 W。照光后1 h用裂隙灯观察统计角膜损伤斑,计算损伤发生率,采用加权概率单位法统计分析损伤阈值ED50。照光后1 h,用裂隙灯和光学相干断层成像(optical coherence tomography,OCT)观察10 s,0.93 W照射的角膜损伤斑;照光后1 d,角膜取材HE染色观察10 s,0.93 W和1.24 W照射角膜损伤特点。结果SC光源2 s和10 s兔角膜损伤阈值为926 J/cm^2(95%置信区间845~1 137 J/cm^2)和3 330 J/cm^2(95%置信区间2 761~3776 J/cm^2)。照光后1 h,裂隙灯观察阈值水平(0.93 W)角膜损伤斑为均匀的凹坑样小圆斑;OCT观察角膜损伤累及上皮层和浅层基质。照光后1 d,HE染色观察,阈值水平(0.93 W)角膜上皮层增厚和浅层基质细胞核深染;1.5倍阈值(1.24 W)导致角膜上皮层紊乱空泡化,基质细胞核消失,内皮细胞丢失。结论SC光源2 s和10 s兔角膜损伤阈值为926 J/cm^2和3 330 J/cm^2。阈值水平损伤角膜上皮层和浅层基质,略高阈值水平导致角膜全层损伤。

Objective To study the pathological characteristics of corneal injury caused by supercontinuum(SC)source and determine the damage threshold ED50.Methods The corneas of thirteen New Zealand white rabbits were irradiated with 770~2 500 nm SC source having a corneal spot diameter of 0.56 mm.Two groups were established by exposure duration:Group A(exposed for 2 s)and Group B(exposed for 10 s).They were divided further into four groups by irradiation power:the power for Group A1-A4 were 1.24 W,1.15 W,1.07 W and 1.00 W,and that for Group B1-B4 0.93 W,0.86 W,0.80 W and 0.75 W.The corneal lesions were observed with slit lamp an hour after the irradiation,then the incidences of corneal lesions were calculated.The ED50 was analyzed with probit analysis.The corneall esions were observed with slit lamp and optical coherence tomography(OCT)an hour after the irradiation for 10 s at the power of 0.93 W.The characteristics of corneal lesions were observed with HE staining a day after the exposure for 10 s at the power of 0.93 W and 1.24 W respectively.ResultsThe ED50 s of rabbits corneal injury caused by SC source for 2 s and 10 s were 926 J/cm2(95%confidence interval 845~1 137 J/cm2)and 3 330 J/cm2(95%confidence interval 2 761~3 776 J/cm2)respectively.An hour after the irradiation at threshold level(0.93 W)for 10 s,it was shown by slit lamp that the corneal lesions were uniform pit-like small circular spots,the observation with OCT indicated that the corneal lesions involved epithelial layer and shallow stroma.HE staining was used a day after the irradiation.For threshold level(0.93 W)power,only the thickness of corneal epithelium and the hyperchromatic of shallow stroma could beseen,while the power(1.24 W)as 1.5 times of the threshold resulted in disordered vacuolization of corneal epithelial layer,disappearance of stromal cell nucleus and loss of endothelial cells.Conclusions The ED50 of corneal injury in rabbits exposed to SC source for 2 s and 10 s is 926 J/cm2 and 3 330 J/cm2.SC source atthreshold level will damage corneal epithelium and anterior stroma,and that at slightly higher level will lead to corneal full-thickness injury.