Psychophysics of Reading—XIV. The Page Navigation Problem in Using Magnifiers

Abstract

Most people with low vision require magnification to read. A magnifier's field of view often contains only a few letters at a time. Page navigation is the process by which the reader moves the magnifier from word to word, and from the end of one line to the beginning of the next line. Page navigation takes time and reduces reading speed. The major questions addressed in this paper are: (1) What role does page navigation play in limiting reading speed? and (2) Are the window width requirements for reading (number of characters in the field for a criterion performance level) increased by the need for page navigation? We measured the reading speeds of three normal-vision and seven low-vision subjects in two ways: with drifting-text requiring no page navigation, and with a closed-circuit TV (CCTV) magnifier which required page navigation. We built special hardware to record the location of the CCTV's magnified field in the text. These recordings were used to separate forward-reading time (left-to-right movement through the text) from retrace time (navigational movement). For normal-vision subjects, forward-reading and retrace times were about equal. For low-vision subjects, retrace times were shorter than forward-reading times, indicating that the forward-reading performance was limited by visual, not navigational, demands. The retrace time did have an impact, however, ranging from 17 to 50% of the overall time. The window requirements for reading with page navigation (CCTV) were larger than those for reading without page navigation (drifting-text). The difference was more than a factor of three for normal-vision subjects and close to a factor of two for low-vision subjects (10 characters for CCTV vs 5.2 characters for drifting-text for 85% of maximum reading speed.

Short-Term In-Office Practice Improves Reading Performance with Stand Magnifiers for People with AMD

“…2,17,67,73,74 The "practice stand" introduced these impediments to reading-reduced field of view, the requirement for manipulation of a stand, and navigation across the text during reading-and thus simulated reading with an STM but without the optical limitations such as aberrations. Therefore, it was surprising that our results did not support the hypothesis that large print reading practice with the stand would provide a faster improvement in STM reading rate than large print practice without the stand.…”

“…[1][2][3][4][5][6]12 The maximum reading rate for people with normal vision is faster than that for subjects with low vision even when the print size is enlarged. [13][14][15][16][17][18] Introduction of a magnifier for people with faster reading rates is likely to result in more obvious reductions in reading rate compared with people with slower reading rates.…”

Reading With Optical Magnifiers: Page Navigation Strategies and Difficulties

“…Previous studies of magnifier movements have either used fullysighted participants reading with optical magnifiers 3,4 or visually impaired participants reading with closed-circuit television (CCTV) systems 5,6 ; to our knowledge magnifier movements of visually impaired readers using optical magnifiers have not been investigated. Optical magnifiers tend to be prescribed more commonly than CCTVs 7,8 and the method of using an optical magnifier is very different from that of a CCTV.…”

“…The primary aim was to provide an objective quantification of page navigation performance in terms of magnifier movement patterns, navigation times, and navigation errors. The navigation movements necessary to read a paragraph can be divided into two phases 6 : the forward phase during which the magnifier is moved from left to right as the user reads along each line (reading English), and the retrace phase when the magnifier is moved to the left from the end of one line to the start of the next line. We expected that the primary navigation movement in the forward phase would be in the horizontal direction (along the line) with little vertical displacement, while in the retrace phase the navigation movement would include both vertical and horizontal components to return the magnifier to the start of the next line.…”

Avaliação de Sistema de Leitura Portátil (SLP) para baixa visão desenvolvido no Brasil

“…Tabela 1 Análise descritiva da amostra em relação à idade, ocupação, patologia ocular e eficácia de leitura auxílios ópticos é o grande desafio, para melhorar o aproveitamento do resíduo visual (8,9) . O SLP permitiu a leitura de palavras com até oito letras simultaneamente com tamanho de fonte doze, possibilitando melhor visualização e reduzindo as perdas de linha de leitura.…”