Eight weeks after the model was established, full-field ERG was performed, and the phNR was evaluated using an Espion Diagnosys System (Diagnosys LLC, Littleton, MA, USA). According to the procedures described (Zhou et al., 2017a (link)), rats were dark-adapted for at least 6 h and prepared under dim red illumination. After the rats were anesthetized, the pupils were dilated, and the corneas were precoated with 2.5% hydroxypropyl-methylcellulose solution (Gonak; Akorn, Lake Forest, IL, USA). ERG was performed with a pair of gold wire loop electrodes that contacted the surface of the cornea. The responses were amplified and bandpass-filtered between 0.3 and 300 Hz, and the luminance range of the light stimuli was 0.003 to 10.0 (P) cd.s/m2. The amplitudes of the a- and b-waves and OPs were measured. After full-field ERG was performed and OPs were recorded, light stimuli were delivered at four different stimulus strengths (11.38 cd.s/m2–0.33 Hz, 11.38 cd.s/m2–1 Hz, 22.76 cd.s/m2–0.33 Hz, and 22.76 cd.s/m2–0.33 Hz) in a four-step test using a ColorDome unit to measure the phNR.
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