Assessing Visual Processing Deficits

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Description

Cerebral (cortical) visual impairment (CVI) is the leading cause of pediatric visual impairment in developed countries. Despite this clear public health concern, our understanding of the functional visual profile and underlying neurophysiology of this condition remain poorly understood. In the setting of early neurological injury, children with CVI typically show deficits associated with higher order visuospatial processing such as finding a target of interest within a complex scene. Beyond standard ophthalmic testing, it remains unknown how manipulating task demands and other environmental factors influence visual search performance in this population. To address this gap, we have developed a series of novel and naturalistic virtual reality (VR) based search tasks combined with eye tracking. We find that CVI is associated with decreased search efficiency and worsening performance with increased visual task demands when compared to neurotypical controls. Finally, neuroimaging using diffusion based techniques has shown that CVI is associated with a dramatic alteration in white matter connectivity, particularly with respect to visual pathways implicated with the dorsal (i.e. spatial) visual processing stream. This novel VR based approach allows for the assessment of visuospatial abilities in CVI with a high degree of behavioral relevance, ecological validity, and participant engagement, and may also have important clinical applications in assessing environmental factors that affect functional visual processing in CVI.

Participants will:

Recognize the complex profile of visual processing impairments in CVI
Recognize the value of virtual reality in assessing visual search abilities
Recognize information provided by brain imaging in helping to better understand the nature of visual processing deficits in CVI

This session is presented by Lotfi B. Merabet, OD, Ph.D., MPH.

Contributors

Lotfi B. Merabet, OD, Ph.D., MPH

Lotfi Merabet is a clinician-scientist investigating how the brain adapts to visual impairment. He completed his doctorate degree in neuroscience (University of Montréal) and clinical doctorate in optometry (New England College of Optometry). He then continued his post-doctoral training at Harvard Medical School, Boston University, and the MGH Martinos Center for Biomedical Imaging. This was followed by a Master’s degree in Public Health (Harvard). In 2010, he joined the clinical and research faculty of the Massachusetts Eye and Ear and his work is currently supported by the NIH/National Eye Institute. He also serves on the Education and CVI Steering Committees of the Perkins School for the Blind, and is a member of the Board of Trustees for the Carroll Center for the Blind and the National Braille Press.