Impaired Ganglion Cell Function Objectively Assessed by the Photopic Negative Response in Affected and Asymptomatic Members From Brazilian Families With Leber's Hereditary Optic Neuropathy

Gabriel Izan Santos Botelho; Solange Rios Salomão; Célia Harumi Tengan; Rustum Karanjia; Felipo Victor Moura; Daniel Martins Rocha; Paula Baptista Eliseo da Silva; Arthur Gustavo Fernandes; Sung Eun Song Watanabe; Paula Yuri Sacai; Rubens Belfort Jr; Valerio Carelli; Alfredo Arrigo Sadun; Adriana Berezovsky

doi:10.3389/fneur.2020.628014

Impaired Ganglion Cell Function Objectively Assessed by the Photopic Negative Response in Affected and Asymptomatic Members From Brazilian Families With Leber's Hereditary Optic Neuropathy

Front Neurol. 2021 Jan 18:11:628014. doi: 10.3389/fneur.2020.628014. eCollection 2020.

Authors

Gabriel Izan Santos Botelho¹, Solange Rios Salomão¹, Célia Harumi Tengan², Rustum Karanjia^{3

4

5

6}, Felipo Victor Moura², Daniel Martins Rocha¹, Paula Baptista Eliseo da Silva¹, Arthur Gustavo Fernandes¹, Sung Eun Song Watanabe¹, Paula Yuri Sacai¹, Rubens Belfort Jr^{1

7}, Valerio Carelli⁸, Alfredo Arrigo Sadun^{3

4}, Adriana Berezovsky¹

Affiliations

¹ Departamento de Oftalmologia e Ciências Visuais, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil.
² Departamento de Neurologia e Neurocirurgia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil.
³ Doheny Eye Institute, University of California Los Angeles, Los Angeles, CA, United States.
⁴ Department of Ophthalmology, Doheny Eye Center, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States.
⁵ Ottawa Eye Institute, University of Ottawa, Ottawa, ON, Canada.
⁶ Ottawa Hospital Research Institute, Ottawa, ON, Canada.
⁷ Instituto da Visão-IPEPO, São Paulo, Brazil.
⁸ Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna School of Medicine, Bologna, Italy.

Abstract

Purpose: The photopic negative response (PhNR) is an electrophysiological method that provides retinal ganglion cell function assessment using full-field stimulation that does not require clear optics or refractive correction. The purpose of this study was to assess ganglion cell function by PhNR in affected and asymptomatic carriers from Brazilian families with LHON. Methods: Individuals either under suspicion or previously diagnosed with LHON and their family members were invited to participate in this cross-sectional study. Screening for the most frequent LHON mtDNA mutations was performed. Visual acuity, color discrimination, visual fields, pattern-reversal visual evoked potentials (PRVEP), full-field electroretinography and PhNR were tested. A control group of healthy subjects was included. Full-field ERG PhNR were recorded using red (640 nm) flashes at 1 cd.s/m², on blue (470 nm) rod saturating background. PhNR amplitude (μV) was measured using baseline-to-trough (BT). Optical coherence tomography scans of both the retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) were measured. PhNR amplitudes among affected, carriers and controls were compared by Kruskal-Wallis test followed by post-hoc Dunn test. The associations between PhNR amplitude and OCT parameters were analyzed by Spearman rank correlation. Results: Participants were 24 LHON affected patients (23 males, mean age=30.5 ± 11.4 yrs) from 19 families with the following genotype: m.11778G>A [N = 15 (62%), 14 males]; m.14484T>C [N = 5 (21%), all males] and m.3460G>A [N = 4 (17%), all males] and 14 carriers [13 females, mean age: 43.2 ± 13.3 yrs; m.11778G>A (N = 11); m.3460G>A (N = 2) and m.14484T>C (N = 1)]. Controls were eight females and seven males (mean age: 32.6 ± 11.5 yrs). PhNR amplitudes were significantly reduced (p = 0.0001) in LHON affected (-5.96 ± 3.37 μV) compared to carriers (-16.53 ± 3.40 μV) and controls (-23.91 ± 4.83; p < 0.0001) and in carriers compared to controls (p = 0.01). A significant negative correlation was found between PhNR amplitude and total macular ganglion cell thickness (r = -0.62, p < 0.05). Severe abnormalities in color discrimination, visual fields and PRVEPs were found in affected and subclinical abnormalities in carriers. Conclusions: In this cohort of Brazilian families with LHON the photopic negative response was severely reduced in affected patients and mildly reduced in asymptomatic carriers suggesting possible subclinical abnormalities in the latter. These findings were similar among pathogenic mutations.

Keywords: electroretinography; leber's hereditary optic neuropathy; photopic negative response; retinal ganglion cell; visual evoked cortical potentials.