Reading with magnifiers

Abstract

The design of low vision aids for partially sighted people, such as magnifiers, is evaluated theoretically in order to identify meaningful directions of research for improving these aids. Both reading with and without a magnifier involves alternating sequences of locating and recognizing textual information. Little is known, however, about these processes in magnifier reading. On the basis of an extensive review of the literature, two topics are identified that stand out as being in need of experimental investigation: (1) the relationship between the (typo)graphical characteristics of printed text and the location and recognition of textual information, and (2) the interplay of location and recognition processes in magnifier reading, including the role of non-visual factors, such as movements of the hand, trunk, head and eyes in this interplay. With regard to the first topic, it is expected that the visibility and, hence, the recognition of textual information by partially sighted people can be improved by matching the fundamental spatial frequencies of graphical structures with the spatial contrast sensitivity of partially sighted people. With regard to the second topic, it is argued that persistent problems in the design of the magnifiers, such as the optimal window size, can only be resolved by studying reading with a magnifier as a (multimodal) perceptual-motor activity.

Reading With Optical Magnifiers: Page Navigation Strategies and Difficulties

“…We did find a modest correlation between vertical field of view and retrace errors (narrower field, more errors), suggesting that the vertical magnifier field is important in the retrace phase of navigation; however, vertical field was measured for only 20 of the 43 participants. Navigation errors might be better predicted by other factors that we did not evaluate in this study, in particular motor skills including hand-eye coordination 3,19 and manual dexterity. 20 The relationships among visual impairment, manipulative skills, hand-eye coordination, and page navigation skills is an important area for future investigations.…”

The Influence of Manual Dexterity on Reading Speed with a Hand-held Magnifier

“…7 Nonvisual factors include the patient's reading comprehension, 8 and training or practice with the task. 9 The roles of physical and mental abilities in magnifier use have not been studied, although den Brinker and Beek 10 suggested investigation of the effects of eye-hand coordination on magnifier reading. It was therefore the purpose of this study to investigate the effects of manual dexterity on the successful use of the hand-held magnifier.…”

Evidence-Based Practice and Trends in Visual Rehabilitation for Patients with Age-Related Macular Degeneration

“…When reading with a hand-held magnifier, the magnifier has to move along the line and at the same time keep a constant distance from the text to ensure a clear image [62].…”