蛇毒纤溶酶诱导兔眼玻璃体后脱离的实验研究

目的观察蛇毒纤溶酶是否可以诱导兔眼玻璃体后脱离（PVD）,并评价其对视网膜的毒性作用。方法根据随机数字表法将24只新西兰白兔分为A、B、C、D组,每组6只。左眼玻璃体腔注射0.1mL生理盐水作为对照。右眼玻璃体腔分别注入1000U/mL（商品单位）的蛇毒纤溶酶0.04、0.05、0.08、0.1mL,术后1、3、7d通过裂隙灯、间接检眼镜检查,观察眼前后节的变化。术后7d通过组织病理学检查,观察药物注入后是否诱发PVD,并评价其对视网膜结构的影响。结果术后7d对照眼无PVD形成,光学显微镜下见各实验组均有不同程度的部分性PVD形成。A、B、C组的视网膜结构与对照组比较无明显改变;D组可见局限性视网膜内界膜溶解破坏,局部视网膜隆起变薄及脉络膜下渗出的毒性改变。A组和D组的扫描电镜结果与光学显微镜一致。随着玻璃体腔蛇毒纤溶酶注射剂量的增加,玻璃体液化程度加大,PVD的范围也加大。结论兔眼玻璃体腔注射适当剂量的蛇毒纤溶酶,在术后7d可以诱导部分性PVD的形成,且视网膜形态无明显改变。大剂量应用时可见视网膜结构的毒性改变。

Experimental study on snake-venom fibrinogenase inducing posterior vitreous detachment

Background At present,drug-induced posterior vitreous detachment （PVD） is considered to be a new method that could assist or replace the traditional mechanical vitrectomy to prevent and cure the vitreoretinal interface diseases.Plasmin is one of noticeable drugs.Objective This study aimed to investigate whether posterior vitreous detachment （PVD） could be induced in rabbit eyes by intravitreous injection of snake-venom fibrinogenase and evaluate its toxicity to retina tissue.Methods Twenty-four New Zealand rabbits were randomly divided into 4 groups and 6 for each group.0.1 mL balanced salt solution （BSS） was intravitreously injected in all the left eyes of rabbits as the controls,and 40 U（0.04 mL）,50 U（0.05 mL）,80 U （0.08 mL）,100 U（0.1 mL） of snake-venom fibrinogenase were respectively used in the right eyes at the same way.The responses of ocular anterior segment and fundus were examined under the slit lamp biomicroscopy and indirect ophthalmoscopes 1 day,3 and 7 days after injection.The eyeballs of rabbits were enucleated and prepared for histopathological examination under the light microscopy and scan electron microscopy （SEM） at the 7th day after injection.Results No PVD was found in the control eyes on the 7th day after injection.Histopathological examination showed the partial PVD in 2 of 3 eyes in 40 U snake-venom fibrinogenase group,6 of 6 eyes in 50 U snake-venom fibrinogenase group,5 of 5 eyes in 80 U snake-venom fibrinogenase group,and 3 of 3 eyes in 100 U snake-venom fibrinogenase group.Local retina thinning and subchoroidal exudates were seen in 1 eye and local dissolution of retinal internal limiting membranes in 2 of 3 eyes in 100 U snake-venom fibrinogenase group on the 7th day.Compared with the control eyes,no obvious change of retinal structure was found in 40 U,50 U,80 U snake-venom fibrinogenase group under the light microscopy.Scan electron microscope revealed residual sparse collagen fibers on the retinal surface in 2 of 3 eyes in 40 U snake-venom fibrinogenase group and 3 of 3 eyes in 100 U snake-venom fibrinogenase group,showing evident difference with dense vitreous collagen fibers in control group.The degree of vitreous liquefaction and scope of PVD were visibly enhanced with the increase of the dosage of snake-venom fibrinogenase.Conclusion Intravitreous injection of appropriate dosage of snake-venom fibrinogenase can induce partial PVD without obvious damage of retinal structure.100 U snake-venom fibrinogenase results in incomplete PVD,meanwhile,retinal structure changes in rabbit eye.