Daniel H Baker1, Mathieu Simard2, Dave Saint-Amour2, Robert F Hess3. 1. Department of Psychology, University of York, Heslington, York, United Kingdom. 2. Department of Psychology, Université du Québec à Montréal, Montréal, Canada. 3. McGill Vision Research, Department of Ophthalmology, McGill University, Montréal, Canada.
Abstract
PURPOSE: Visual deficits in amblyopia are neural in origin, yet are difficult to characterize with functional magnetic resonance imagery (fMRI). Our aim was to develop an objective electroencephalography (EEG) paradigm that can be used to provide a clinically useful index of amblyopic deficits. METHODS: We used steady-state visual evoked potentials (SSVEPs) to measure full contrast response functions in both amblyopic (n = 10, strabismic or mixed amblyopia, mean age: 44 years) and control (n = 5, mean age: 31 years) observers, both with and without a dichoptic mask. RESULTS: At the highest target contrast, the ratio of amplitudes across the weaker and stronger eyes was highly correlated (r = 0.76) with the acuity ratio between the eyes. We also found that the contrast response function in the amblyopic eye had both a greatly reduced amplitude and a shallower slope, but that surprisingly dichoptic masking was weaker than in controls. The results were compared with the predictions of a computational model of amblyopia and suggest a modification to the model whereby excitatory (but not suppressive) signals are attenuated in the amblyopic eye. CONCLUSIONS: We suggest that SSVEPs offer a sensitive and objective measure of the ocular imbalance in amblyopia and could be used to assess the efficacy of amblyopia therapies currently under development. Copyright 2015 The Association for Research in Vision and Ophthalmology, Inc.
PURPOSE:Visual deficits in amblyopia are neural in origin, yet are difficult to characterize with functional magnetic resonance imagery (fMRI). Our aim was to develop an objective electroencephalography (EEG) paradigm that can be used to provide a clinically useful index of amblyopic deficits. METHODS: We used steady-state visual evoked potentials (SSVEPs) to measure full contrast response functions in both amblyopic (n = 10, strabismic or mixed amblyopia, mean age: 44 years) and control (n = 5, mean age: 31 years) observers, both with and without a dichoptic mask. RESULTS: At the highest target contrast, the ratio of amplitudes across the weaker and stronger eyes was highly correlated (r = 0.76) with the acuity ratio between the eyes. We also found that the contrast response function in the amblyopic eye had both a greatly reduced amplitude and a shallower slope, but that surprisingly dichoptic masking was weaker than in controls. The results were compared with the predictions of a computational model of amblyopia and suggest a modification to the model whereby excitatory (but not suppressive) signals are attenuated in the amblyopic eye. CONCLUSIONS: We suggest that SSVEPs offer a sensitive and objective measure of the ocular imbalance in amblyopia and could be used to assess the efficacy of amblyopia therapies currently under development. Copyright 2015 The Association for Research in Vision and Ophthalmology, Inc.
Authors: Nicholas A Badcock; Petroula Mousikou; Yatin Mahajan; Peter de Lissa; Johnson Thie; Genevieve McArthur Journal: PeerJ Date: 2013-02-19 Impact factor: 2.984
Authors: Annegret Hella Dahlmann-Noor; John A Greenwood; Andrew Skilton; Daniel Baker; Siobhan Ludden; Amanda Davis; Hakim-Moulay Dehbi; Steven C Dakin Journal: BMJ Open Date: 2022-05-24 Impact factor: 3.006