Abstract
Cerebral visual impairment (CVI) classifies visual dysfunction in children arising from brain injury or developmental disorders, and is currently the leading cause of visual dysfunction in children in the developed world. CVI is more heterogenous than injury-induced vision loss in mature brains, is more ambiguous to characterize and treat, and commonly occurs alongside other sensory, cognitive, and motor deficits. Consequently, children with CVI often lack the ability to understand instructions or make the rational, volitional responses required by conventional tests of visual function typically used among high-functioning adults (e.g. acuity, contrast sensitivity, color vision, depth perception, visual fields). Diagnosis of CVI instead relies largely upon the neuroopthalmological examination, which is designed only to detect overt departures from ‘normal’ function and cannot provide the resolution needed to differentiate categories of CVI or precisely grade separate dimensions of visual ability. Here, we present evidence that comprehensive psychophysical assessments of visual function can still be conducted in children with CVI by carefully designing tasks that minimize the influence of cognitive, attentional, and communicative deficits. Our novel tasks leverage predictable spatiotemporal patterns in eye movements that are contingent on the visibility and behavior of particular visual stimuli. We have successfully deployed these tasks among brain-injured children to reliably measure contrast sensitivity (see Mooney et al., 2018), quantify the kinematics of saccades and pursuits, and map asymmetries and abnormalities in spatial visual fields. Our findings suggest that non-verbal, intuitive tests of visual function can be conducted among brain-injured populations without sacrificing the precision and efficiency of the best conventional volition-based tasks (e.g. forced-choice paradigms). In some cases, our tasks appear no less efficient—and potentially less tiresome—than standard vision tests currently used among otherwise healthy adults.
Acknowledgement: Blythedale Children’s Hospital