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Catarina A. Mateus, Aldina A. Reis, Joao Castelhano, Eduardo Silva, Miguel Castelo-Branco; Cortical Impact of Genetic Retinal Degeneration of Ganglion Cell Origin and With Early Visual Loss. Invest. Ophthalmol. Vis. Sci. 2012;53(14):5693.
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© ARVO (1962-2015); The Authors (2016-present)
To characterize cortical neurophysiologic responses in Autosomal Dominant Optic Atrophy (ADOA) patients accross parallel pathways.
We have recorded high density visual evoked potentials, according to the international 10-20 system, with a SCANTM system device (Compumedics NeuroScan, Texas, USA) in a population of 22 subjects (13 families; mean age: 31.9+16.4 years; mean visual acuity: 0.3+0.2) with ADOA submitted to OPA1 mutation analysis. A cap with 64 electrodes was used to collect biosignals induced by stimuli with different characteristics selective for magno and parvocellular pathways (gratings with low spatial frequency (0.25 cpd) with an associated temporal frequency (10 Hz), and static gratings of 4 cpd, respectively). The obtained data were compared with an age-matched control group and also correlated with standard electrophysiological methods (pattern and multifocal visual evoked potentials and pattern electroretinogram). Parametric statistical analysis was performed using ANOVA at a significance level of p<0.05. Spearman correlation analysis was also performed.
In the primary visual cortex (Occipital electrodes), visual evoked responses were considerably reduced for all types of stimulation in patients (0.0001<p<0.02), as compared with controls. However, unlike controls, amplitudes remained relatively stable across posterior-anterior cortical regions, and they may even be higher than controls in anterior hemispheric when using low spatial frequency stimuli.The characteristic inter-hemispheric parvo- and magnocellular asymmetric pattern in found controls was lost in patients (p>0.05). However, in Kjer group is evident a dominance of the responses evoked by low frequency checkerboard stimuli presented in the peripheral vision or full-field, as compared with those obtained with high frequency stimuli (0.0002<p<0.0056).Interestingly, cortical data were not correlated with ganglion cell and optic nerve outcome measures, suggesting independence of damage.
Our results suggest that damage is not confined to ganglion and optic nerve cell damage in ADOA. Concomitant cortical impairment is also present, not only related to central vision, but also in peripheral representations, with involvement of both parvo- and magnocellular systems.
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