Pseudorandom full-field electroretinograms reflect different light adaptation mechanisms

Purpose To investigate the magnitude and time course of pseudorandom ffERG during light adaptation. Methods Ten healthy subjects (26 +/- 10.1 years) underwent 20 min of dark adaptation, and then the ffERG was evoked by pseudorandom flash sequences (4 ms per flash, 3 cd.s/m(2)) driven by m-sequences (2(10)-1 stimulus steps) using Veris Science software and a Ganzfeld dome over a constant field of light adaptation (30 cd/m(2)). The base period of the m-sequence was 50 ms. Each stimulation sequence lasting 40 s was repeated at 0, 5, 10, 15 and 20 min of light adaptation. Relative amplitude and latency (corrected by values found at 0 min) of the three components (N1, P1, and N2) of first-order (K-1) and first slice of the second-order (K-2.1) 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 (tau) 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. Results Regarding the K-1 ffERG, N1 K-1, P1 K-1, and N2 K-1 presented an amplitude increase as a function of the light adaptation (N1 K-1 tau value = 2.66 min +/- 4.2; P1 K-1 tau value = 2.69 min +/- 2.10; and N2 K-1 tau value = 3.49 min +/- 2.96). P1 K-1 and N2 K-1 implicit time changed as a function of the light adaptation duration (P1 K-1 tau value = 3.61 min +/- 5.2; N2 K-1 tau value = 3.25 min +/- 4.8). N1 K-1 had small implicit time changes during the light adaptation. All the K-2,K-1 components also had nonsignificant changes in amplitude and implicit time during the light adaptation. Conclusions Pseudorandom ffERGs showed different mechanisms of adaptation to retinal light. Our results suggest that K-1 ffERG is generated by retinal mechanisms with intermediate- to long-term light adaptation, while K-2.1 ffERG is generated by retinal mechanism with fast light adaptation course.

Automated summary

This study investigated the amplitude and time course of pseudorandom ffERG during light adaptation. Results showed that different ffERG components had different mechanisms of adaptation to retinal light. The K-1 ffERG was influenced by retinal mechanisms with intermediate- to long-term light adaptation, while the K-2.1 ffERG was influenced by retinal mechanisms with a fast light adaptation course.