An Electroretinographic Changes of Laser-induced Experimental Branch Retinal Vein Occlusion in the Rabbits

To verify whether laser-induced branch retinal vein occlusion in the rabbit can be used as the experimental model for the human study. The temporal retinal vein of the right eye was occluded with argon laser photocoagulator with parameters of 500 micrometerspot size, 0.2 second duration, 150-200 microWatt power in twelve pigmented rabbits. The left eye was used as a control. An electroretinogram was taken before and 1,3,7,15 and 28 days after vein occlusion. B/a ratio and oscillatory potentials increased in the eyes with occluded veins. Comparing the pre-occlusion values with those of post-occlusion, the changes were not statistically significant. But differences between the values of right and those of left eye were significant. We can suppose that the discrepancies may result from the difference in timing of examination. In conclusion, the rabbit model of laser-induced experimental branch retinal vein occlusion may not be adequate for the study of clinical branch retinal vein occlusion.

Electroretinographic Findings in Patients with Branch Retinal Vein Occlusion

To evaluate the electroretinographic findings in cases of branch retinal vein occlusion(BRVO), Electroretinogram(ERG) were performed according to ISCEV(International Society for Clinical Electrophysiology of Vision) protocol in 17 unilateral BRVO patients. According to fluorescein angiographic acute stage group, hemorrhagic area of fundus was evaluated from retinal photo obtained by fundus camera. And correlation between hemorrhagic area and ERG was evaluated In acute stage group, the b-wave amplitude and b/a ratio of scotopic maximal combined response and oscillatory potential were significantly decreased at the affected eye compared unaffected eye. These findings were not found in chronic stage group. The relationship between hemorrhagic area and ERG finding was not detected in acute stage group. ERG findings in the acute stage of BRVO show that main pathologic lesion of BRVO is located in the inner retinal layer and inner retinal circulation. With further follow-up study, It is possible to use ERG data as a predictor of the course of BRVO.