Juliana Bizerra Assis1, Alódia Brasil2,3, Terezinha Medeiros Gonçalves Loureiro1, Veronica Gabriela Ribeiro da Silva1, Anderson Manoel Herculano1, Dora Fix Ventura4, Luiz Carlos Lima Silveira1,5, Jan Kremers6, Givago Silva Souza1,5. 1. Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Pará, Brazil. 2. Núcleo de Medicina Tropical, Universidade Federal do Pará, Belém, Pará, Brazil. alodiabrasil@ufpa.br. 3. Faculdade de Nutrição, Instituto de Ciências da Saúde, Universidade Federal do Pará, Av. Generalíssimo Deodoro 92, Umarizal, Belém, Pará, 66055-240, Brazil. alodiabrasil@ufpa.br. 4. Instituto de Psicologia, Universidade de São Paulo, São Paulo, Brazil. 5. Núcleo de Medicina Tropical, Universidade Federal do Pará, Belém, Pará, Brazil. 6. Department of Ophthalmology, University Hospital Erlangen, Erlangen, Germany.
Abstract
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/m2) driven by m-sequences (210-1 stimulus steps) using Veris Science software and a Ganzfeld dome over a constant field of light adaptation (30 cd/m2). 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 (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. RESULTS: 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 = 2.66 min ± 4.2; P1 K1 τ value = 2.69 min ± 2.10; and N2 K1 τ value = 3.49 min ± 2.96). P1 K1 and N2 K1 implicit time changed as a function of the light adaptation duration (P1 K1 τ value = 3.61 min ± 5.2; N2 K1 τ value = 3.25 min ± 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. CONCLUSIONS: 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.
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/m2) driven by m-sequences (210-1 stimulus steps) using Veris Science software and a Ganzfeld dome over a constant field of light adaptation (30 cd/m2). 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 (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. RESULTS: 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 = 2.66 min ± 4.2; P1 K1 τ value = 2.69 min ± 2.10; and N2 K1 τ value = 3.49 min ± 2.96). P1 K1 and N2 K1 implicit time changed as a function of the light adaptation duration (P1 K1 τ value = 3.61 min ± 5.2; N2 K1 τ value = 3.25 min ± 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. CONCLUSIONS: 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.
Authors: N S Peachey; G A Fishman; P E Kilbride; K R Alexander; K M Keehan; D J Derlacki Journal: Invest Ophthalmol Vis Sci Date: 1990-02 Impact factor: 4.799
Authors: Alódia Brasil; Tina I Tsai; Givago da Silva Souza; Anderson Manoel Herculano; Dora Fix Ventura; Luiz Carlos de Lima Silveira; Jan Kremers Journal: J Vis Date: 2019-03-01 Impact factor: 2.240