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L. Alarcon-Martinez, M. Avilés-Trigueros, R. Blanco-Velasco, P. De la Villa, M. Vidal-Sanz; Scotopic Threshold Response as an Index of Retinal Ganglion Cell Function in Axotomized Adult Rat Retina. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3602.
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To investigate the functional changes in the inner retina after intraorbital optic nerve transection (IONT) in adult albino SD rats.
In adult SD rats (180-220 gr) the left optic nerve was transected intraorbitally to induce the acute death of retinal ganglion cells (RGC). Electroretinographic (ERG) responses were recorded simultaneously from both eyes prior to the IONT and at different survival intervals ranging from 7, 14, 30 to 75 days. The ERG a- and b- waves and the scotopic threshold responses (STR) were analyzed in scotopic conditions. White light stimuli of intensities ranging from 10-6 to 10-4 cd·s·m-2 were used to record the STR and stimulus light intensities ranging from 10-4 to 102 cd·s·m-2 were used to analyze the a- and b-wave amplitudes of standard ERG recordings.
One week after IONT the STR mean amplitude was decreased significantly to approximately 40% of the values registered for the non-operated, contralateral eye (p<0.05). Standard ERG a- and b-waves showed a small, reduction in their amplitudes to approximately 80 and 90%, respectively, when compared to their contralateral eyes; but not changes in their implicit times. Two weeks after IONT the STR mean amplitude was approximately 35% of its contralateral intact eye. The a- and b-wave amplitudes had further decreased to approximately 75% of their control eyes, and their implicit time had increased significantly (P<0.001). Ten weeks after IONT, the STR remained significantly reduced to approximately 40% of the contralateral eyes, whereas the a- and b-waves reached values of approximately 90% of their contralateral eyes.
Intraorbital optic nerve transection, which is known to induce massive degeneration of RGCs, is related to selective changes in the scotopic threshold response wave amplitudes. STR could be a useful functional parameter for monitoring RGC function in animal models of optic neuropathic diseases.
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