周期性眼外负压吸引对兔视网膜超微结构的影响

目的探讨不同强度的周期性眼外负压吸引对兔视网膜超微结构的影响。方法以新西兰大白兔为实验动物分为对照组和实验组,对实验组分别应用改良准分子激光原位角膜磨镶术负压吸引环置于兔角巩膜缘,以眼球外负压每3s100mmHg(1mmHg=0.133kPa)的速度升高至负压(200±20)mmHg(实验组Ⅰ)、(300±20)mmHg(实验组Ⅱ)、(400±20)mmHg(实验组Ⅲ)、(500±20)mmHg(实验组Ⅳ)。即时眼压分别为35、45、55及75mmHg,维持约5s后释放压力至0,间隔1min后重复上述操作共10个循环,隔日实验1次。2周后电镜观察不同部位兔视网膜超微结构,并比较实验组和对照组的差异。结果实验组Ⅰ与对照组相比未见到明显变化,实验组Ⅱ视网膜超微结构与对照组相比发现细胞器略有增多,提示细胞代谢增强。Ⅲ、Ⅳ组视网膜超微结构有一定变化,其中Ⅳ组超微结构破坏,细胞有坏死征象。结论不同终点眼压的周期性眼外负压吸引对视网膜超微结构影响不同,小于45mmHg基本无影响,55mmHg左右有一定影响,大于75mmHg有明显的破坏作用。

The ultrastructure changes of rabbit retina after periodical vacuum suction

OBJECTIVE: To study the effects of periodical vacuum-suction of different pressures on the ultrastructure of rabbits' retina. METHODS: Rabbits involved in the present study were divided into a control group and four treatment groups, which were treated with vacuum-suction of different pressures through scleral suction ring. The suction pressure was increased at a rate of 100 mm Hg/3 sec (1 mm Hg = 0.133 kPa) and reached (200 +/- 20) mm Hg (group I), (300 +/- 20) mm Hg (group II); (400 +/- 20) mm Hg (group III) and (500 +/- 20) mm Hg (group IV). The suction pressure was maintained for 5 seconds before released to zero. The corresponding intraocular pressure examined by Tonopen was 35 mm Hg, 45 mm Hg, 55 mm Hg and 75 mm Hg in these 4 groups, respectively. This circle was repeated for 10 times with 1 minute interval. The test was repeated every other day. The retina was examined by electron microscope after 2 weeks. RESULTS: There was no obvious difference in the retina ultrastructure between the control group and group I. The retina ultrastructure changed slightly in group II which showed more active metabolism. Some significant changes were found in group III and group IV with cell necrosis in group IV. CONCLUSION: Different elevations of intraocular pressure following periodical vacuum-suction have different effects on the retina of rabbit. Pressure less than 45 mm Hg has almost no effect, but some effects appear at 55 mm Hg pressure, and obviously damages are caused by 75 mm Hg pressure.