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Lyndon daCruz, Francesco Merlini, Maura Arsiero, Fatima Anaflous, Avi Caspi, 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 Outlined Shapes Using The Argus® Ii Retinal Prosthesis System: A Comparison With The Full Shapes Recognition Task. Invest. Ophthalmol. Vis. Sci. 2012;53(14):5507.
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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 outlined shapes, and to compare the results with the subjects’ ability to identify geometrical full shapes (Arsiero et al., 2011).
13 Blind subjects fitted with the Argus II retinal prosthesis were asked to identify geometrical outlined shapes in a forced-choice closed-set test. The test consisted of presenting outlined white or gray shapes on an LCD computer monitor, in random order, on a black background. At each set presentation, we varied the shape’s size among 5 groups (XL=22.6, L=14.3, M=9.0, S=5.6, XS=3.6 cm). The 8 shapes were: square, triangle, circle, rectangle, pentagon, hexagon, cross and half circle. We measured the time and the success rate in identifying them with or without the use of the Argus II system.
With the system "on" the mean score of correct answers across the population of tested subjects were the following (% correct answers):White Full ShapesXL: 31%, L: 32%, M: 34%, S: 27%, XS: 34%White Outlined ShapesXL: 47%, L: 41%, M: 46%, S: 34%, XS: 32%Gray Full ShapesXL: 37%, L: 37%, M: 35%, S: 27%, XS: 26%Gray Outlined ShapesXL: 39%, L: 42%, M: 29%, S: 27%, XS: 26%
Subjects fitted with the Argus II System show a better ability to perform outlined shapes identification task than full shapes identification task for most sizes of shapes tested. By design, the Argus II retinal prosthesis system offers a platform for different implementations of the conversion of an image to a stimulation pattern on the retina. The results of this study can be used to develop imaging processing tools such as edge detection in order to have more consistent benefit for all patients on the shapes recognition task.
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