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Published on: October 18, 2018
Reading with optical magnifiers: page navigation strategies and difficulties
Alex Bowers1, Allen M Y Cheong, Jan E Lovie-Kitchin
1The Schepens Eye Research Institute, Harvard Medical School, Boston, MA 02114, USA. alex.bowers@schepens.harvard.edu
Summary
People with age-related macular degeneration (AMD) reading with magnifiers face challenges, especially during the retrace phase. Navigation difficulties are not well predicted by vision measures, suggesting a need for motor skills assessment and training.
Area of Science:
- Ophthalmology
- Low Vision Rehabilitation
- Human Factors Engineering
Background:
- Reading with magnifiers requires efficient page navigation, involving forward and retrace movements.
- Difficulties in page navigation are suspected to limit reading efficiency for individuals with visual impairments using magnifiers.
- Objective measurement of page navigation in this context has been lacking.
Purpose of the Study:
- To objectively quantify the page navigation strategies and difficulties encountered by individuals with age-related macular degeneration (AMD) while reading with handheld or stand magnifiers.
- To identify specific challenges in the forward and retrace phases of magnifier navigation.
- To explore the relationship between visual function and objective measures of page navigation performance.
Main Methods:
- Forty-three participants with AMD used their habitual magnifiers to read texts.
- Magnifier movements and navigation errors during reading were recorded using a 3SPACE Isotrak system.
- Visual acuity, visual fields, and subjective reports of navigation difficulties were collected.
Main Results:
- Forward navigation was significantly longer than retrace navigation (4:1 ratio).
- The most frequent navigation error involved incorrect magnifier positioning at the end of the retrace phase.
- Near word acuity correlated with forward and retrace times and forward errors; vertical visual field correlated with retrace errors.
- Subjective reports of navigation difficulty did not predict objective performance.
Conclusions:
- Page navigation, particularly the retrace phase, presents significant challenges for individuals with AMD using magnifiers.
- Current vision measures do not adequately predict navigation difficulties, highlighting the potential role of motor skills.
- Future research should explore motor skill influences and the efficacy of training or assistive devices to improve navigation performance.
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