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Natalie Yee-Guan Chan, Taku Fujiyama, Gary S Rubin; Investigating the Relationship between Public Transport Difficulty and Life-Space for people with Age Related Macular Degeneration and Glaucoma. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):501.
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This project aims to assess the impact of Age-related Macular Degeneration (AMD) and Glaucoma on mobility in public transport environments. We hypothesize that a single underlying latent trait of transport difficulty exists and that both groups will report greater transport difficulty leading them to travel less widely than people of similar age with normal vision.
Focus groups were used to design a self-assessment instrument to measure the difficulty of public transport navigation tasks. Rasch analysis was used to validate the questionnaire, calculate difficulty ratings for each transport item and ability levels for each participant. Principal component analysis of the residuals (PCAR) was used to test for the presence of sub dimensions. The study sample comprised 414 people, 325 with AMD, 30 with glaucoma, and 61 with normal vision. Difficulty ratings were calculated for each transport item and transport difficulty scores calculated for each participant. Differential Item Functioning (DIF) analysis was used to investigate differences between patients with AMD and glaucoma. Regression analysis was used to explore the impact of vision loss on transport difficulty and the relationship between transport difficulty and the extent and frequency of travel (Life Space Scores).
Twenty two items were identified that fit the Rasch model of a single unidimensional latent trait which we termed 'transport difficulty'. PCAR indicated that there were no other significant dimensions being measured. DIF did not exist according to eye condition. Regression analysis showed that Transport Difficulty and Life Space Scores did not differ according to eye condition but were associated with self-reported vision level (p<0.001).
This study is the first to investigate the effect of low vision on transport difficulty and Life Space scores. The results show that people with vision loss from AMD or glaucoma experience greater difficulty using public transportation and that the pattern of difficulty for individual tasks and the impact of this difficulty on Life Space scores is similar for both patient groups.
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