Hemianopsia

Evaluate the efficiency of audiovisual stimulation in virtual reality for improving the visual perception of children, adolescents, and young adults with hemianopia resulting from pediatric brain tumors. These individuals can lose up to 50% of their visual field, significantly impacting their independence, mobility, and daily lives.

In patients with hemianopsia following stroke or brain injury, we will determine if stimulating the visual field with images from a PowerPoint slide set can increase the visual field.

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 purpose of this research is to better understand the impact of cortically-induced blindness (CB) and the compensatory strategies subjects with this condition may develop on naturalistic behaviors, specifically, driving. Using a novel Virtual Reality (VR) program, the researchers will gather data on steering behavior in a variety of simulated naturalistic environments. Through the combined use of computer vision, deep learning, and gaze-contingent manipulations of the visual field, this work will test the central hypothesis that changes to visually guided steering behaviors in CB are a consequence of changes to the visual sampling and processing of task-related motion information (i.e., optic flow).

Brain malignancies are the most common cause of death from cancer in the pediatric population and a major source of morbidity amongst survivors. Many children with a brain tumour often suffer from visual field defects (hemianopia) dramatically impacting their daily life with poorer social interaction, difficulties learning, playing sports and engaging with peers. Practically, they bump into people and objects and have problems in finding their way in unfamiliar places and in detecting incoming objects in their blind field. There is growing recognition of the diverse and deep impact of hemianopia on physical and mental health, quality of life, and social outcomes of the affected individuals and their family. However, despite the frequent impact of brain tumours on the visual function and functional vision, ophthalmologic evaluations are not standard of care for all brain tumour patients and there are no standardized protocols of vision loss management in the pediatric population with hemianopia. There is an unmet need of restoring perception in the blind field in individuals with hemianopia consecutive to pediatric brain tumor. Our laboratory has developed a visual rehabilitation procedure based on the combination of adaptative audio and visual target tracking in a 3D environment in virtual reality. Participants perform audiovisual stimulation at home in a headset, with remote control from the laboratory. Preliminary on data on paediatric patients with hemianopia consecutive to a brain tumour indicate feasibility and potential effectiveness of a 6-week Re:Vision program on visual fields, visual perception and quality of life. Our objective is to evaluate the effectiveness of Re:Vision, an 8-week visual telerehabilitation program, on visual perception in 50 individuals aged 10-40 years old with hemianopia consecutive to a pediatric brain tumor in a phase IIa/b multi-centric clinical study across Canada. This intervention provides more equitable access to individuals, with the ability to receive rehabilitation therapy at home without supervision by a healthcare professional, meaning that Canadians living outside urban centres could take advantage of specialized therapies with remote supervision. This is the first study that could lead to a major change in the management of these patients. It could open the door for visual rehabilitation strategies to other population of visually impaired children, significantly impacting public health strategies.