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Kemi Adeyemo, Pamela E Jeter, Collin Rozanski, Amelie-Francoise Nkodo, Gislin Dagnelie, ; Comparison of retinal prosthesis wearers to individuals with severe vision loss in the development of an Ultra-Low Vision questionnaire.. Invest. Ophthalmol. Vis. Sci. 2014;55(13):1838.
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© ARVO (1962-2015); The Authors (2016-present)
To assess whether a small group of individuals whose vision has been partially restored with an Argus II retinal prosthesis system provides ratings similar to individuals with minimal remaining natural vision or individuals whose natural vision is no longer useful.
A 149 item questionnaire addressing the difficulty of visually performing tasks with minimal visual requirements was administered to 6 Argus II wearers, 53 minimally-sighted, and 22 formerly-sighted individuals. Minimally-sighted subjects self-reported having some vision whereas the formerly-sighted indicated they did not have any useable remaining vision. Items were rated as “not applicable”, “not difficult”, “moderately difficult”; “very difficult”; or “impossible to do visually”. A Rasch analysis was performed on the data, and the item score distribution for the Argus II group was compared to that of the other two groups.
The person measure scores for the Argus II prosthesis wearers were statistically significantly lower than for the minimally-sighted individuals, by 2.95 logits on average (95% CI: 1.4,4.5; p<0.001). However, Argus II wearers’ ratings were not statistically significantly different from those by the formerly-sighted individuals, with only a 0.79 logit mean difference (95% CI: -0.9,2.5; p=0.36) in the person measure. Analysis of differential item measures showed that none of the items was rated significantly differently by the two groups. The formerly-sighted individuals also had statistically significantly lower scores than the minimally-sighted individuals, by 2.16 logits on average (95% CI: 1.2,3.1; p<0.001). Four questions were rated significantly differently by the two groups, but not all in the same direction.
Argus II wearers and formerly-sighted individuals reported significantly more difficulty using their vision during activities requiring minimal visual function when compared to individuals reporting some remaining, minimal vision, but the differences did not significantly depend on items surveyed. This finding helps support the construct validity of using these questionnaire items to detect differences in self-reported visual function across a diverse group of individuals with ultra-low vision.
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