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Jamila Malika Ahmad, Gabriela Ioshimoto, Andre Liber, Dora Ventura; Scotopic ERG Protocols for Rabbits. Invest. Ophthalmol. Vis. Sci. 2019;60(9):5965.
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© ARVO (1962-2015); The Authors (2016-present)
There is a wide use of the ERG in rabbits in studies of the visual system. However, specific ERG protocols for rabbits are scarce in literature. Several studies are based on the ISCEV protocol or even the reduced protocol to evaluate the retinal function. Here, the clinical ERG protocol proposed by ISCEV was compared and analyzed with two extended protocols tested in rabbits.
Full-field ERG was performed in 6 New Zealand rabbits. The short scotopic protocol includes 3 differing levels of intensity (lowest intensity 0.0095 cd.s/m2 and highest 9.5 cd.s/m2), the intermediate scotopic protocol includes 11 (lowest intensity 0.0003 cd.s/m2 and highest 20 cd.s/m2), and the long scotopic protocol includes 20 different intensities (lowest intensity 0.000625 cd.s/m2 and highest 20 cd.s/m2). The a- and b-wave amplitudes and implicit times of the ERGs were measured and formatted by the Naka–Rushton equation.
The short protocol based on the ISCEV standard took approximately 5 to 7 minutes to complete. A-wave was detected at 3 cd.s/m2(85,2mV± 23.1 m V) and, for the maximum scotopic response at 9.5 cd.s/m2, the a- and b-wave amplitudes were 132.83mV± 22.5 and 267.47mV± 44.4, respectively. The intermediate protocol took roughly 30 to 35 minutes; a-wave was detected at 0.03 cd.s/m2(8.4mV±1.9) and the maximum scotopic response of the a- and b-wave amplitudes were 105.59mV± 13.9 and 217.27mV± 45.5, respectively, at 20 cd.s/m2. The b-wave VlogI function of the intermediate protocol presented a plateau at 0.03 cd.s/m2, moment that the a-wave becomes evident. This plateau was also presented in the b-wave VlogI function of the long protocol, which took approximately 50 to 55 minutes to complete. The maximum response of the a- and b-wave amplitudes were 111.37mV± 9.1 and 228.17mV± 25.1, at 20 cd.s/m2 respectively. The comparison of the Naka-Rushton analysis between the intermediate and long protocol did not show any difference.
The short protocol allows comparison of responses from different retinal cell types and is useful under time restrictions, but the extended protocols offer the possibility of curve fitting to the Naka-Rushton function and quantitative estimation of functional parameters. The choice between the two extended protocols falls on the intermediate protocol, once the long version avoids the need for a reinforcement of anesthesia.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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