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 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 electrotetinogram.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 (Plt;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 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 nearly normal amplitudes.This result indicates that functions of 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. (Chin J Ocul Fundus Dis,1998,14:104-107)
ObjectiveTo investigate the effect of heat shock protein B8 (HspB8) downregulation on retinal ganglion cell (RGC) and retinal function in the mice model of optic nerve injury (ONC).MethodsAdeno-Associated Virus (AAV) 2 AAV2-shHspB8-GFP was constructed to knockdown HspB8. 66 adult male C57/BL6 mice were randomly divided into the control group, the ONC group, the AAV2-shHspB8 group, the ONC+AAV2-shHspB8 group, and the ONC+AAV2- GFP group. There were 10, 20, 16, 10 and 10 mice respectively, and both eyes were used as experimental eyes. Western blot was used to evaluate the expression of HspB8 on day 3 and 7 after ONC. By GFP immunofluorescence staining, the efficacy of AAV2-shHspB8-GFP transfer was accessed. Moreover, it was possible to identify functional and RGC survival differences between groups by optomotor response (OMR), dark adapted full-field flash electroretinogram (ff-ERG), oscillatory potentials (OPs), photopic negative response (PhNR) and retinal flat-mount RGC counting 5 days after ONC. Comparisons between two groups were made using Mann-Whitney U test, unpaired t-test, unpaired t-test with Welch’s correction, one-way ANOVA, and Bonferroni t test.ResultsCompared with the control group, the expression of HSPB8 protein in the retina of mice in ONC3 group was significantly increased, and the difference was statistically significant (F=43.63, P＜0.01). Compared with the control group, the ONC group showed obviously lower visual acuity (P＜0.01), lower a-wave, b-wave, OPs, PhNR amplitude, longer b-wave latency (P＜0.05), and the survival rates of RGC in ONC3 group, ONC5 group and ONC7 group decreased in a time-dependent manner(F=384.90, P＜0.01). Transfection of AAV2 efficiency was highest on 4 weeks after IVT. Besides, there was no significant differences between the control group and the AAV2-shHspB8 group on visual acuity, ff-ERG, OPs, PhNR and RGC survival (P>0.05). In comparison of the control group, we found that RGC survival of the ONC5+AAV2-shHspB8 group was significantly elevated (F=10.62, P＜0.01).ConclusionsExpression of HspB8 on the retina can be induced by ONC. The investigation of RGC counting, visual acuity, and ff-ERG revealed that optic nerve injury destructed functionality of mice retina and resulted to RGC death ultimately. The Most crucial finding of this research is that HspB8 knockdown had a neuroprotective effect in RGC after ONC.