Abstract
People with low vision, especially those with Central Field Loss (CFL), need magnification to read. The flexibility of Electronic Vision Enhancement Systems (EVES) offers several ways of magnifying text. Due to the restricted field of view of EVES, the need for magnification is conflicting with the need to navigate through text (panning). We have developed and implemented a real-time gaze-controlled system whose goal is to optimize the possibility of magnifying a portion of text while maintaining global viewing of the other portions of the text (condition 1). Two other conditions were implemented that mimicked commercially available advanced systems known as CCTV (closed-circuit television systems)—conditions 2 and 3. In these two conditions, magnification was uniformly applied to the whole text without any possibility to specifically select a region of interest. The three conditions were implemented on the same computer to remove differences that might have been induced by dissimilar equipment. A gaze-contingent artificial 10° scotoma (a mask continuously displayed in real time on the screen at the gaze location) was used in the three conditions in order to simulate macular degeneration. Ten healthy subjects with a gaze-contingent scotoma read aloud sentences from a French newspaper in nine experimental one-hour sessions. Reading speed was measured and constituted the main dependent variable to compare the three conditions. All subjects were able to use condition 1 and they found it slightly more comfortable to use than condition 2 (and similar to condition 3). Importantly, reading speed results did not show any significant difference between the three systems. In addition, learning curves were similar in the three conditions. This proof of concept study suggests that the principles underlying the gaze-controlled enhanced system might be further developed and fruitfully incorporated in different kinds of EVES for low vision reading.
Highlights
Age-related Macular Degeneration (AMD), a severe maculopathy, is the most common cause of low vision and often causes dramatic Central Field Loss (CFL) among elderly people who are constrained to use eccentric viewing [1]
The clear and interesting pattern is that using closedcircuit televisions (CCTVs) with reformatting encourages subjects to magnify text more often: in this mode, all subjects spend more than 50% of the time with a magnification level that is above the initially displayed character size
In terms of reading speed, our results show a modest advantage for the gazecontrolled system with respect to the improved CCTV and no difference when compared with the CCTV with reformatting system
Summary
Age-related Macular Degeneration (AMD), a severe maculopathy, is the most common cause of low vision and often causes dramatic Central Field Loss (CFL) among elderly people who are constrained to use eccentric viewing [1]. This scotoma in the center of the visual field dramatically disrupts reading performance [2,3]. Reading speed is a key performance measure.
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