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Thomas Georgi, Domagoj Ivastinovic, Ralf Hornig, Michaela Velikay-Parel; Usability Of The Graz Mobility Test For Artificial Vision. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4967.
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In a previous study we introduced a newly designed mobility test (GMT) for evaluation of visual function in Retintis pigmentosa patients with severe visual impairment and its future application for evaluating functional progress in artificial vision. For the documentation of progress in test- retest applications the GMT has to show consistency and reliability. Therefore our new study investigated the learning effects of the GMT in various time intervals. The hypothesis was that the subjects will reach their performance plateau in the first test and will never exceed it in retests.
Low vision patients (n=14) with visual acuity (VA) ranging from no light perception (NLP) to finger counting (FC) passed through a mobility test consisting of four different, structurally similar mazes with black obstacles. Each course was passed four to six times. The test was repeated after 1, 2, 3 and 6 months. Passage time and the number of contacts were measured. Two groups were formed according their visual acuity, group 1 (NLP and Light Perception (LP)) and group 2 (Handmotions (HM) - FC). Group 2 approximates the expected performance in artificial vision.
The average of the overall passage times of group 1 was significantly slower than group 2, and the number of contacts significantly higher. The passage time of each group differed significantly at all time intervals of group 2. The difference of the retests passage times at the various time intervals was not significant within each group (one way ANOVA Group1: F=0.648, p=0.6, Group2: F=0.533, p=0.712).
The GMT proved to be clinical relevant to significantly differentiate subjects with respect to VA levels during repeated testing. Learning effects are unlikely to confound assessment in artificial vision. Hence potential benefits of retinal prostheses could be evaluated by comparing pre- and postoperative values or results in an on and off mode.
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