大量玻璃体积血对兔视网膜电图检查的影响

Effects of large amount of vitreous hemorrhage on electroretinogram in rabbits

目的研究大量玻璃体积血对兔眼视网膜电图检查的影响。方法（１）用物理学方法测量血液对白色闪光的透过率；（２）在经玻璃体气体压缩术形成的兔眼玻璃体腔中注入０．５ｍｌ自体血，利用强闪光视网膜电图（ｅｌｅｃｔｒｉｃａｌｒｅｓｉｓｔａｎｃｅｇａｕｇｅ，ＥＲＧ）技术和光强度－振幅曲线的计算分析ＥＲＧ的变化；测定玻璃体切除术消除积血前后ＥＲＧ。结果随着浓度和厚度的增加，血液对光线的透过率呈指数下降趋势。玻璃体积血使常规ＥＲＧ检查波形消失，用增强３．５ｌｏｇ单位的强闪光刺激可以引出ＥＲＧ波形。玻璃体切除术后ＥＲＧｂ波可逐渐恢复。结论血液对白色闪光有较强的吸收能力，光线被玻璃体内积血吸收可以导致常规ＥＲＧ波形消失，此时应用强闪光ＥＲＧ可以测得接近于正常的ＥＲＧｂ波最大反应，提示视网膜功能并未因玻璃体大量积血而发生不可逆病变。玻璃体切除术清除积血后，ＥＲＧ波形缓慢恢复。

Objective To test the effects of large amount of blood in the vitreous on electrophysiological examination. Methods The reductions of transmission of flash light through a serial dilution and depth of whole blood were measured.An experimental model of vitreous hemorrhage in rabbits was established by injecting 0.5ml autologous uncoagulated whole blood into the vitreous cavities after compression with an expanding perfluoropropane gas bubble.Pars plana vitrectomy was performed to clear the blood clots 2 weeks after blood injection.Ganzfeld and bright flash electroretinography were performed through six week observation period. Results Blood reduced remarkably the transmission of bright flash light.Massive vitreous hemorrhage had a dense filtering effect and extinguished the Ganzfeld but not the bright flash electroretinogram.About 3.5log units higher of the intensities of bright flash light than that of conventional method could stimulate the responses of ERG b waves in blood injected eyes.Slow recovery of Ganzfeld ERG b waves after vitrectomy were noted within 2 weeks(P<0.05),and ERG b wave reached at 80～90% of normal level during the third week. Conclusion The ERG b waves,which become undetectable because of absorption of the dense opacities of the vitreous in eyes with a large amount of vitreous hemorrhage,can be recorded in bright flash light conditions with nearly normal amplitudes.This result indicates that functions of the retina were not severely damaged by the large amount of vitreous hemorrhage.The injection of large amount of blood into vitreous cavities may cause a transient reduction of the amplitudes of ERG b waves.