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Maura Arsiero, Lyndon da Cruz, Francesco Merlini, Jose A. Sahel, Paulo E. Stanga, Farhad Hafezi, Robert J. Greenberg, Argus II Study Group; Subjects Blinded By Outer Retinal Dystrophies Are Able To Recognize Shapes Using The Argus II Retinal Prosthesis System. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4951.
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To test if subjects blinded by outer retinal dystrophies and fitted with the Argus II Retinal Prosthesis System, can recognize geometrical shapes.
Blind subjects fitted with the Argus II retinal prosthesis were asked to identify geometrical shapes, in a forced-choice closed-set series of tests. The first test consisted of presenting to the subjects outlined white or gray shapes. In the second test we presented solid white or gray shapes. In the third test, at each presentation, we varied the shape’s size among 5 groups (XL= 22.6, L=14.3, M=9, S=5.6, XS=3.6 cm). In all cases, the 8 shapes were: square, triangle, circle, rectangle, pentagon, hexagon, cross, half circle. They were presented on an LCD computer monitor, in random order, on a black background. We measured the time and the success rate in identifying them with or without the use of the Argus II system.
In the first test (outlined shapes) with the system "on" the mean score across the population of tested subjects was 56.9 % (SD 24.8%) while it was 18.8 % (SD 9.4 %) with the system "off." In the first test for the gray outlined shapes it was 56.6 % (SD 24.3%) with the system "on" and 33.7 % (SD 15 %) with the system "off." In the second test (solid shapes) for the white solid shapes we got 30.8 % (SD 21.9%) with the system "on" and 12.5 % (SD 4.6 %) with the system "off." In the second test for the gray solid shapes the score was 32.7 % (SD 24.5%) with the system "on" and 13 % (SD 2.2 %) with the system "off". In the third test with the system "on" 36 % of the tested subjects are able to identify the shapes in all the 5 sizes.
Blind subjects fitted with the Argus II retinal prosthesis system are able to perform identification tasks better with the system on compared with off. Moreover, our results indicate that size of optotypes affects score differently for subgroups of subjects. The better results obtained in identifying outlined shapes with respect to the solid shapes indicates that the total illumination may play a role in the performance of the subjects.
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