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.
Diagnosed hemianopsia (> 18 months).
History of a diagnosis of brain tumour
Being stable for the tumour for >18 months (either on therapy or not)
Male and female
< 10 years old.
> 40 years old.
Ocular disease
Both eyes with media opacity that impairs microperimetry testing.
Crossover
Audiovisual stimulation
DeviceThe MOT IVR audiovisual stimulation task involves the 3D multiple-object-tracking paradigm composed of 6-8 high-contrast spheres which features are adapted to the visual ability of individuals with low-vision (luminosity = 80 nits, size = 1° to 3° visual angle). The spheres move for 20s. following random linear paths, bouncing on one another and on the walls of a virtual 3D cube when collisions occur. The participant, comfortably seated, is asked to track the moving cued target among moving distractors for 20s. A spatial sound is correlated to the movement of the cued target. After 20s., the movement stops and the participant is asked to select, using a laser pointer, the cued sphere among the distractors (mark-all procedure). Speed of the spheres is regulated by a staircase 1:1 procedure. The stimulation can here be stopped by the participant if required. After 3 blocks of 15x20s., the system stops and goes on stand-by mode until the next session. Data are collected in real time.
Binocular Visual Field
Difference in the number of points perceived in the Esterman binocular field test between intervention and non-intervention groups and pre/post-intervention
Patient-related Outcome Measures - National Eye Institute - Visual Function Questionnaire - 25
Difference in quality of vision questionnaire scores between intervention and non-intervention groups and pre/post-intervention. Scores are from 0 to 100. High scores represents better outcome.
Patient-related Outcome Measures - World Health Organization - Quality of Life questionnaire - BREF
Difference in quality of vision questionnaire scores between intervention and non-intervention groups and pre/post-intervention. Scores are from 0 to 100. High scores represents better outcome.
Reading Speed
Difference in the number of words per minute (at critical print size) between intervention and non-intervention groups and pre/post-intervention
Fixation Stability
Difference in fixation stability (BCEA 63%, degree square) between intervention and non-intervention groups and pre/post-intervention
Brain Activity - Visually-evoked potentials
Difference in brain activity (VEP EEG) between intervention and non-intervention groups and pre/post-intervention. Measures of N75, P100 and N175 latency (ms) and amplitude (microV) during monocular pattern reversal stimulation.
Retinal Integrity
Difference in retinal fiber layer thickness (RNFL) between intervention and non-intervention groups and pre/post-intervention
Brain imaging - Tractography
Measures of optic tract density will be performed by diffusion tensor MRI (DTI - fractional anisotropy, tractography) between intervention and non-intervention groups and pre/post-intervention
Brain imaging - Retinotopy
Retinotopic visual stimulation will be performed by visual stimulation at 4 different retinal positions and measured using population receptive field (voxels value) between intervention and non-intervention groups and pre/post-intervention
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University Health Network, Toronto
Lead sponsor
Alberta Children's Hospital
Collaborator
St. Justine's Hospital
Collaborator
The Hospital for Sick Children
Collaborator
British Columbia Children's Hospital
Collaborator
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