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AR Bowers, JE Lovie-Kitchin, AM Y Cheong; The Effect of Passage Width on Page Navigation With Optical Magnifiers . Invest. Ophthalmol. Vis. Sci. 2002;43(13):4786.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: In order to read efficiently with an optical magnifier, the magnifier has to be navigated correctly during the forward (left to right) and retrace (right to left) phases of reading. The results of an earlier study (1) suggested that page layout might have a significant effect on retrace time. In this study we investigated the effect of passage width on forward and retrace navigation performance with optical magnifiers. Methods: Magnifier movements (X, Y and Z) were recorded using a 3SPACE Isotrak system whilst 20 visually impaired subjects read short stories (90 words) in two passage widths (5cm and 15cm) using their habitual hand-held or stand magnifier. Forward and retrace navigation times were determined and navigation errors were quantified for equivalent passage lengths (same total number of characters) in the two passage formats. Results: Total navigation time was significantly less (p = 0.02) and reading rate significantly faster (by 8%) for the 5cm than the 15cm passage. Total forward navigation time was significantly shorter (p < 0.001), but total time for retrace was significantly longer (p = 0.008) for the 5cm passage than the 15cm passage. Hence the percentage of total time devoted to retrace was significantly higher for the 5cm than the 15cm passage (30% cf. 18%, p = 0.001). There was no significant difference in the total number of navigation errors for the two passage widths. Conclusion: Our results suggest that, for users of optical magnifiers, it may be beneficial to provide reading material in narrow columns, similar to newspaper format. Although reading rate was faster for the narrower passage width (due to the reduction in forward navigation time), the total time for retrace was longer. In the ideal world, the most efficient reading with optical magnifiers would be achieved using a paragraph layout that minimised both retrace and forward navigation time. 1. Bowers A. R., Lovie-Kitchin J. E. and Woods R. L. (2001) Eye movements and reading with large print and optical magnifiers in macular disease. Optom. Vis. Sci. 78, 325-334. Research supported by small grant from Department of Vision Sciences, Glasgow Caledonian University.
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