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Gregoire Cosendai, Maura Arsiero, Stephanie Patnode, Robert J. Greenberg, Argus II Study Group; Longitudinal Functional Vision Ability Improvements in ArgusTM II Retinal Prosthesis System Subjects Using the Massof Activity Inventory. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4968.
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© ARVO (1962-2015); The Authors (2016-present)
To monitor longitudinal changes in functional vision ability in blind subjects who received and used the Argus II Retinal Prosthesis System in their daily lives. The evaluation was done using the Massof Activity Inventory instrument.
The Massof Activity Inventory (AI) is an adaptive questionnaire which assesses the self-reported difficulty of Tasks (T) nested under Goals (G) all relating to four different domains of activities: Orientation and Mobility (O&M), Visual Information (VI), Visual Motor (VM), and Reading (R). It aims to quantitatively measure the subject’s functional ability in objectives of daily living, social interactions and recreation. Subjects are asked to rate the importance of each Goal, the difficulty of that Goal, and then difficulty of Tasks associated with that Goal. Thirty subjects with severe vision loss (bare light perception or worse) due to retinitis pigmentosa received the retinal prosthesis system. The questionnaire was administered at baseline and after 6, 12, 18 and 24 months (M) of use with the Argus II. For each time point, we reported the logit by finding the maximal likelihood for a Rasch distribution with an Andrich rating model for the cohort, and reported changes from baseline to each longitudinal time, matching subjects.
The results show a steady improvement of Goals, starting at 6M, becoming significant at 12M, further improving to a very significant +0.5 logit at 24M. The Tasks first show no effect to 18M and show small improvement at +0.2 logit at 24M. The breakdown of Tasks shows that most benefit was gained on VM, following the same pattern of improvement of Goals. O&M, VI and R show no significant change.
Results from the Massof AI show that subjects report functional visual tasks becoming easier after starting to use the Argus II Retinal Prosthesis System. The improvement is steady and becomes very significant at 24 months. This improvement can be explained by the improvement on visual motor tasks, which is consistent with the visual function gains expected with the system.
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