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Jasmine Junge, Deborah A Orel-Bixler; Critical spacing of contour interaction for children with Cerebral Visual Impairment (CVI). Invest. Ophthalmol. Vis. Sci. 2018;59(9):631.
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© ARVO (1962-2015); The Authors (2016-present)
Cerebral visual impairment (CVI) is the leading cause of vision loss in children in industrialized nations and results from an insult to the developing brain. While anecdotal information exists regarding visual functions in children with CVI, quantification of known visual challenges is still needed. Children with CVI have more difficulty with identifying symbols in the presence of contour interaction. The goal of this study was to determine the critical spacing of contour interaction in children with CVI as compared to a group of normally sighted children.
Binocular visual acuity was measured during a comprehensive vision examination for 21 children (ages 4-20 years; mean 9.6 years) presenting with a diagnosis of CVI and 37 normally sighted children (ages 3-11 years; mean 6.2 years). Single Lea symbols with contour flanker bars at 50%, 100%, and infinite (unflanked) spacing were presented in a two-alternative forced choice task using the apple and the house as the test optotypes.
For the children with CVI, visual acuity ranged from 0.0 to 1.38 logMAR. The mean difference in visual acuity was 0.24 logMAR for isolated vs. 50% spacing, 0.16 logMAR for 100% vs. 50% spacing and 0.08 logMAR for isolated vs. 100% spacing. In normally sighted children, the mean difference in visual acuity was 0.05 logMAR for isolated vs. 50% spacing, 0.03 logMAR for 100% vs. 50% spacing and 0.02 logMAR for isolated vs. 100% spacing. A two-line best-fit template was fit to the data for both groups.
The critical spacing for contour interaction in children with CVI is larger than that for normally sighted children. The effects of contour interaction may add to the visual difficulty of a given task for children with CVI. This information may be valuable when making recommendations on print size and spacing in educational materials for children with CVI.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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