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L. daCruz, B. Coley, P. Christopher, F. Merlini, V. Wuyyuru, J. A. Sahel, P. Stanga, E. Filley, G. Dagnelie, Argus II Study Group; Patients Blinded by Outer Retinal Dystrophies Are Able to Identify Letters Using the Argus TM II Retinal Prosthesis System. Invest. Ophthalmol. Vis. Sci. 2010;51(13):2023.
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To test if patients blinded by outer retinal dystrophies and fitted with the Argus II Retinal Prosthesis System, can identify letters on a computer monitor.
Blind subjects (vision reduced to bare light perception or worse) fitted with the Argus II Retinal Prosthesis were asked to identify white letters on a black background, on an LCD computer monitor in a forced-choice closed-set test. For the test, 22 subjects were presented the letters L,T,E,J,F,H,I,U (group A); 11 subjects the letters A,Z,Q,V,N,W,O,C,D,M (group B) and 6 subjects the letters K,R,G,X,B,Y,S,P (group C). Letters were Power Point, Century Gothic, 600 point viewed at 12 inches. The letters were presented in random order, 4 times with the System on and 4 times with the System off. The time taken to identify the letter correctly was recorded.
The mean percent correct and standard deviations for all subjects tested were as follows. Group A 72.6 ± 24.2 % system on and 16.8 ± 10.0% system off, Group B 61.4 ± 30.0% system on and 9.5% ± 5.9% system off, and group C 63.5% ± 28.3% system on and 17.2% ± 1.7% system off. Using a Chi squared test there was a significant difference between systems on and off for each group (p < 0.001). The average time for the letters to be correctly identified was 44.8s group A, 62.3s Group B and 100.3s Group C with System on.
Blind patients fitted with the Argus II Retinal Prosthesis System were able to perform significantly better with the system on compared with off in a forced-choice, closed-set, letter identification task. This is the first time that a retinal prosthetic device has been shown to allow a large group of blind patients to successfully identify letters.
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