title: The effect of transcranial direct current stimulation on contrast sensitivity and visual evoked potential amplitude in adults with amblyopia.
abstract: Amblyopia is a neurodevelopmental disorder of vision that occurs when the visual cortex receives decorrelated inputs from the two eyes during an early critical period of development. Amblyopic eyes are subject to suppression from the fellow eye, generate weaker visual evoked potentials (VEPs) than fellow eyes and have multiple visual deficits including impairments in visual acuity and contrast sensitivity. Primate models and human psychophysics indicate that stronger suppression is associated with greater deficits in amblyopic eye contrast sensitivity and visual acuity. We tested whether transcranial direct current stimulation (tDCS) of the visual cortex would modulate VEP amplitude and contrast sensitivity in adults with amblyopia. tDCS can transiently alter cortical excitability and may influence suppressive neural interactions. Twenty-one patients with amblyopia and twenty-seven controls completed separate sessions of anodal (a-), cathodal (c-) and sham (s-) visual cortex tDCS. A-tDCS transiently and significantly increased VEP amplitudes for amblyopic, fellow and control eyes and contrast sensitivity for amblyopic and control eyes. C-tDCS decreased VEP amplitude and contrast sensitivity and s-tDCS had no effect. These results suggest that tDCS can modulate visual cortex responses to information from adult amblyopic eyes and provide a foundation for future clinical studies of tDCS in adults with amblyopia.
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
authors.forename: Zhaofeng
authors.initials: Z
authors.lastname: Ding
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
authors.forename: Jinrong
authors.initials: J
authors.lastname: Li
authors.affiliation: McGill Vision Research, McGill University, Canada.|School of Optometry and Vision Science, University of Auckland, New Zealand.
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Spiegel
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
authors.forename: Zidong
authors.initials: Z
authors.lastname: Chen
authors.affiliation: School of Optometry, The Hong Kong Polytechnic University, Hong Kong, SAR, China.
authors.forename: Lily
authors.initials: L
authors.lastname: Chan
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
authors.forename: Guangwei
authors.initials: G
authors.lastname: Luo
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
authors.forename: Junpeng
authors.initials: J
authors.lastname: Yuan
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
authors.forename: Daming
authors.initials: D
authors.lastname: Deng
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
authors.forename: Minbin
authors.initials: M
authors.lastname: Yu
authors.affiliation: School of Optometry and Vision Science, University of Auckland, New Zealand.|School of Optometry and Vision Science, University of Waterloo, Canada.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Thompson
mesh_terms: D000328:Adult; D000550:Amblyopia / Q000175:diagnosis* / Q000503:physiopathology*; D000704:Analysis of Variance; D015350:Contrast Sensitivity; D005074:Evoked Potentials, Visual; D005260:Female; D006801:Humans; D008297:Male; D065908:Transcranial Direct Current Stimulation; D014792:Visual Acuity; D014793:Visual Cortex / Q000503:physiopathology; D055815:Young Adult