Controversies related to mfVEP use

Abstract

AbstractPurpose To address the usefulness of mfVEP use in clinical research on neurophthalmology, with a focus on optic neuropathies (Leber and Kjer Optic Neuropathies) as well as acquired cortical scotomas.Methods We have tested a sample of 17 asymptomatic Leber’s hereditary optic neuropathy (LHON) who were mtDNA 11778G>A mutation carriers from two generations of the same pedigree (mean age ± SD = 27.94 ± 12.97 years; mean visual acuity ± SD= 1.25 ± 0.11). We included an age‐matched control group (n=18; mean age ± SD = 33.29 ± 14.22 years; mean visual acuity ± SD= 1.09 ± 0.14). We have also studied 22 subjects (44 eyes) from 13 families with Autosomal Dominant Optic Atrophy (ADOA) submitted to OPA1 mutation analysis. Quantitative psychophysical methods were used to assess konio and parvocellular chromatic pathways. Electrophysiological assessment included the Multifocal Electroretinogram (mfERG) and Pattern Electroretinogram (PERG), respectively. Global Pattern and Multifocal VEP (visual evoked potentials) were used to assess retinocortical processing. Finally we performed multimodal studies (mfVEP and structural and functional MRI) to study visual loss in a patient with a cortical scotoma.Results We found evidence for functional impairment in color vision pathways in LOHN carriers, with relative preserved VEP and mfVEP responses. In ADOA mfVEP showed distinct evidence for cortical impairment that is only moderately explained by the retinal phenotype, suggesting additional damage mechanisms at the cortical level. fMRI based visual field cortical mapping revealed changes in retinotopic organization that were more difficult to identify using mfVEP.Conclusion mfVEP is an interesting tool in clinical research , but its application in the clinical diagnosis setting is still difficult.