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T. Georgi, D. Ivastinovic, M. Rüther, K. Pirker, R. Hornig, M. Velikay-Parel; A Novel Technique to Analyse Scanning via Head Movement Whilst Walking Through the Graz Mobility Test. Invest. Ophthalmol. Vis. Sci. 2008;49(13):1781. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
It has been postulated that visual scanning via head movement can double the spatial frequency information in prosthetic vision. So far head movement recordings were only obtained from persons sitting at a computer screen. We report our initial experience with a novel technique to record and assess scanning via head movement whilst walking in standardized motion conditions for low vision patients with reduced peripheral visual field.
A people tracking system with an integrated trajectory projection system was established to record horizontal and vertical scanning movements of people whilst walking through the Graz mobility test; this was based on a video from multiple synchronized and calibrated cameras with overlapping fields of view. A customized computer program was designed to assess the amount and degree of head movement. 3 comparable low vision Retinitis pigmentosa patients were tested repeatedly in 1, 2 and 3 month time intervals.
Passage time, walking speed, number of contacts, frequency of scanning movements and average scanning angle were successfully recorded and assessed. In repeated testing significant changes were observed once the patients became familiar with the mobility test. The maximum learning effect expressed by the passage time was achieved within the first test session and was never exceeded in the following sessions. However further changes in the remaining parameters were observed in each patient, displaying behavioural changes correlating to the level of comfort during the task performance.
Our novel technique can objectively identify various coping strategies for mobility performance in low vision RP patients.
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