Kelly E. Lusk

Peripheral Vision of Youths with Low Vision: Motion Perception, Crowding, and Visual Search

PURPOSE Effects of low vision on peripheral visual function are poorly understood, especially in children whose visual skills are still developing. The aim of this study was to measure both central and peripheral visual functions in youths with typical and low vision. Of specific interest was the extent to which measures of foveal function predict performance of peripheral tasks. METHODS We assessed central and peripheral visual functions in youths with typical vision (n = 7, ages 10-17) and low vision (n = 24, ages 9-18). Experimental measures used both static and moving stimuli and included visual crowding, visual search, motion acuity, motion direction discrimination, and multitarget motion comparison. RESULTS In most tasks, visual function was impaired in youths with low vision. Substantial differences, however, were found both between participant groups and, importantly, across different tasks within participant groups. Foveal visual acuity was a modest predictor of peripheral form vision and motion sensitivity in either the central or peripheral field. Despite exhibiting normal motion discriminations in fovea, motion sensitivity of youths with low vision deteriorated in the periphery. This contrasted with typically sighted participants, who showed improved motion sensitivity with increasing eccentricity. Visual search was greatly impaired in youths with low vision. CONCLUSIONS Our results reveal a complex pattern of visual deficits in peripheral vision and indicate a significant role of attentional mechanisms in observed impairments. These deficits were not adequately captured by measures of foveal function, arguing for the importance of independently assessing peripheral visual function.

The effects of various mounting systems of near magnification on reading performance and preference in school-age students with low vision

This single-subject study explored the effects of different mounting systems of prescribed near magnification (handheld, stand-mounted, spectacle-mounted, and electronic) on reading performance and preference in students with low vision. Participants included five students ranging from 3rd to 11th grade, and with various etiologies. Reading performance and preference varied widely with each mounting system, with no clear patterns across students. The differences in mounting systems did appear to be a determining factor in the reading performance and preference among students and should be taken into account when selecting and prescribing devices for students.

Management of Vision Impairment in Children

Although it is common for pediatric ophthalmologists to provide medical and surgical eye care for children with visual impairment, a treatment algorithm that addresses vision rehabilitation concerns is needed. Distance and near access to the visual environment is critical for children to acquire literacy skills. Defining all aspects of the child’s comprehensive visual function combined with referral for appropriate educational placement and programming provides the child with the best opportunity to function independently in the classroom and at home. Knowledge of basic magnification devices is a useful adjunct to any pediatric ophthalmology practice.