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A. Hayasaka, S. Machida, H. Miyamoto, T. Ishibe, Y. Tazawa; Changes in Full–Field Cone and Multifocal Electroretinograms After Retinal Peripapillary Cauterization in Cats . Invest. Ophthalmol. Vis. Sci. 2005;46(13):2255.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To determine whether the neural activity of retinal ganglion cells (RGCs) and their axons contribute to full–field cone electroretinograms (ERGs) and multifocal ERGs (mfERGs) in cats. Methods: Retinal peripapillary cauterization was performed on 8 eyes of 8 cats to eliminate the neural activity of RGCs and their axons. Sham surgery was performed on the fellow eyes. Full–field cone ERGs and mfERGs were recorded from both eyes before, and at 1, 2, 4, and 12 weeks after the cauterization. Cone ERGs were elicited by Ganzfeld stimuli of 0.84 log cd–s/m2 on a white background light of 34 cd/m2. The stimuli for the mfERG recordings consisted of 37 black and white hexagonal elements that were reversed pseudorandomly at a binary m–sequence at 75, 37.5, or 9.4 Hz. The cone ERG and mfERG waveforms of the cauterized eyes were subtracted from those of controls to isolate the responses that were lost following the cauterization. Results: For the cone ERGs, the mean ratio of the amplitudes of the cauterized eyes to the control eyes (experimental/control amplitude ratio) for the photopic negative response (PhNR) decreased progressively with time after the surgery, and the decrease was significant at the 4th and 12th week (P <0.005 at 4th week andP <0.001 at 12th week). For the mfERGs, the mean experimental/control amplitude ratio of the N2–P2, P2–N3, N3–P3 and the s–wave were significantly reduced postoperatively as early as 1 week (P <0.005). No further decrease of the amplitudes of these waves was noted thereafter. Digital subtraction revealed waves with peaks at 13 (P13) and 33 ms (P33) and troughs at 25 (N25) and 45 ms (N45). The amplitudes of N25–P33 and P33–N45 increased significantly with lower stimulus frequencies (P <0.05). Conclusions: These findings strongly suggest that RGCs and/or their axons make a significant contribution to both the full–field cone ERGs and mfERGs in cats. In addition, the functional loss of these neural elements after peripapillary cauterization can be detected at an earlier stage by mfERGs than by full–field cone ERGs.
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