1.319 μm近红外激光致兔角膜损伤后修复的长期观察

Observation on Long-term Repair of Rabbit Corneal Injury Induced by 1.319 μm Near-infrared Laser

目的 建立1.319μm近红外激光致兔角膜全层损伤动物模型,观察角膜损伤后长期修复的过程及结果。方法 实验对象新西兰白兔10只,采用波长1.319μm近红外激光损伤兔左眼角膜(右眼作为正常对照组),每只兔眼1个照射光斑,光斑直径3 mm,照射时间0.7 s,能量密度140 J/cm^(2)。利用裂隙灯显微镜、光学相干断层成像(optical coherent tomography,OCT)、组织病理学检测等技术手段,于损伤前、损伤后即刻至6个月内多个时间点进行角膜损伤修复观察。结果 波长1.319μm激光在本实验照射条件下的兔角膜损伤为全层性损伤。裂隙灯显微镜观察可见激光损伤形成的白色损伤斑先增大后缩小,损伤后6个月基本消失,同时角膜先肿胀增厚后迅速消退;OCT观察及定量测量可见损伤斑中心角膜全层厚度最大可达正常角膜厚度的2倍,增厚区域直径最大可达照射光斑直径的2.6倍;组织病理学观察可见激光损伤后坏死上皮和内皮细胞快速脱落,新生上皮和内皮细胞随后覆盖损伤区,基质细胞损伤后数小时核染色质脱失,后期修复过程出现大量浸润细胞。结论 波长1.319μm激光在能量密度140 J/cm^(2)时可致兔角膜全层性损伤,在不加治疗干预的情况下,经6个月可自愈恢复正常状态。

Objective To observe the long-term repair process of rabbit cornea injury induced by 1.319 μm near-infrared laser radiation.Methods The experimental subjects were 10 New Zealand white rabbits.The cornea of left eyes of New Zealand white rabbits were damaged by 1.319 μm near-infrared laser(The right eyes were not treated with anything as normal control group), and each eye was exposed to one spot.The spot diameter was 3 mm, the exposure duration 0.7 s and the radiant exposure 140 J/cm^(2).The cornea repair process was observed at multiple time points from pre-exposure to 6 months after laser injury with slit lamp microscopy, optical coherent tomography(OCT) and histological evaluation.Results Full-thickness corneal injury was induced by 1.319 μm laser with the above exposure parameters.Slit lamp microscopy observation showed that the area of the white corneal lesion first increased and then decreased, which disappeared after 6 months.Meanwhile, the cornea swelled and thickened first and then recovered rapidly.OCT cross-sectional observation and quantitative analysis showed that after the laser injury, the whole thickness of the injured central cornea was twice greater than that of the uninjured part.The maximum diameter of the thickened area of the cornea was 2.6 times of the diameter of the laser spot.Histological observation showed that the necrotic epithelial and endothelial cells shed rapidly after the laser injury, after which the new epithelial and endothelial cells covered the damaged area.The nuclear chromatin of the injured stroma cells lost several hours after the laser exposure and a large number of infiltrating cells appeared during the repair process.Conclusions Full-thickness corneal injury may be induced by 1.319 μm laser at the dose of 140 J/cm^(2).Without therapeutic intervention, the cornea damage will repair to normal after 6 months.