Abstract
To investigate the magnitude and time course of pseudorandom ffERG during light adaptation. Ten healthy subjects (26 ± 10.1years) underwent 20min of dark adaptation, and then the ffERG was evoked by pseudorandom flash sequences (4ms per flash, 3cd.s/m2) driven by m-sequences (210-1 stimulus steps) using Veris Science software and a Ganzfeld dome over a constant field of light adaptation (30cd/m2). The base period of the m-sequence was 50ms. Each stimulation sequence lasting 40s was repeated at 0, 5, 10, 15 and 20min of light adaptation. Relative amplitude and latency (corrected by values found at 0min) of the three components (N1, P1, and N2) of first-order (K1) and first slice of the second-order (K2.1) kernel at 5 time points were evaluated. An exponential model was fitted to the mean amplitude and latency data as a function of the light adaptation duration to estimate the time course (τ) of the light adaptation for each component. Repeated one-way ANOVA followed by Tukey post-test was applied to the amplitude and latency data, considering significant values of p < 0.05. Regarding the K1 ffERG, N1 K1, P1 K1, and N2 K1 presented an amplitude increase as a function of the light adaptation (N1 K1 τ value = 2.66min ± 4.2; P1 K1 τ value = 2.69min ± 2.10; and N2 K1 τ value = 3.49min ± 2.96). P1 K1 and N2 K1 implicit time changed as a function of the light adaptation duration (P1 K1 τ value = 3.61min ± 5.2; N2 K1 τ value = 3.25min ± 4.8). N1 K1 had small implicit time changes during the light adaptation. All the K2,1 components also had nonsignificant changes in amplitude and implicit time during the light adaptation. Pseudorandom ffERGs showed different mechanisms of adaptation to retinal light. Our results suggest that K1 ffERG is generated by retinal mechanisms with intermediate- to long-term light adaptation, while K2.1 ffERG is generated by retinal mechanism with fast light adaptation course.
Published Version
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