Visual Field Defect Homonymous Bilateral

Visual field defects are a common consequence of acquired brain injuries and affect people of all ages. These vision problems make everyday life more difficult-for example, when reading, driving, or moving around safely. However, there is currently no effective therapy to improve visual field defects. Previous training methods have focused on maximizing brain activity during a task. However, new findings show that the best performance is achieved when the brain is already in a state of high communication before the task. Our research shows that people can learn to increase communication between brain regions through neurofeedback. Studies have shown that neurofeedback can help people after a stroke: it improves the coordination of brain areas that are important for movement, thereby helping to increase mobility. Building on these findings, this study investigates whether EEG neurofeedback can support the visual centers in the brain to improve vision in patients with chronic visual field defects. The main objective of the study is to evaluate the effectiveness of neurofeedback in improving visual field defects. More specifically, the investigators are investigating the development of visual ability (expansion of the visual field, contrast sensitivity).

This is a randomized, pilot interventional study in participants with visual field deficit (VFD) caused by cortical lesion. Damage to the primary visual cortex (V1) causes a contra-lesional, homonymous loss of conscious vision termed hemianopsia, the loss of one half of the visual field. The goal of this project is to elaborate and refine a rehabilitation protocol for VFD participants. It is hypothesized that visual restoration training using moving stimuli coupled with noninvasive current stimulation on the visual cortex will promote and speed up recovery of visual abilities within the blind field in VFD participants. Moreover, it is expected that visual recovery positively correlates with reduction of the blind field, as measured with traditional visual perimetry: the Humphrey visual field test or an eye-tracker based visual perimetry implemented in a virtual reality (VR) headset. Finally, although results will vary among participants depending on the extent and severity of the cortical lesion, it is expected that a bigger increase in neural response to moving stimuli in the blind visual field in cortical motion area, for those participants who will show the largest behavioral improvement after training. The overarching goals for the study are as follows: Group 1a will test the basic effects of transcranial random noise stimulation (tRNS) coupled with visual training in stroke cohorts, including (i) both chronic/subacute ischemic and chronic hemorrhagic VFD stroke participants, and (ii) longitudinal testing up to 6 months post-treatment. Group 1b will test the effects of transcranial tRNS coupled with visual training on a Virtual Reality (VR) device in stroke cohorts, including both chronic/subacute ischemic and chronic hemorrhagic VFD stroke participants. Group 2 will examine the effects of tRNS alone, without visual training, also including chronic and subacute VFD stroke participants and longitudinal testing.

The investigators will develop and test different configurations of high-power prisms to expand the field of vision of patients with visual field loss to assist them with obstacle detection when walking. The study will involve multiple visits (typically four) to Schepens Eye Research Institute for fitting and testing with the prism glasses. The overall objective is to determine best designs and fitting parameters for implementation in prism devices for future clinical trials.