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.
18 years of age or older.
Presence of some intact visual cortical areas (other than primary visual cortex) in the damaged brain hemisphere. This assessment will be made from MRI or CT scans of the subject's head, which will be obtained via standard release from their neurologist.
First ever ischemic or hemorrhagic stroke with damage to primary visual cortex, and rendered blind over a portion of their visual field.
Ischemic stroke patients will be either subacute (within 6 months of their stroke) or chronic (more than 6 months)
No evidence of damage to the primary visual cortex.
Visual cortex damage as a result of a subsequent stroke (not primary).
Total cortical blindness, covering both left and right visual fields.
Unable to fixate visual targets precisely or unable to perform the visual training exercises as directed.