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Robert W Massof, Ashley Deemer, James Deremeik, Chris Bradley, Kyoko Fujiwara, Rob Chun, Frank Werblin; Comparison of visual performance measures with virtual bioptic vs full-field magnification in a head-mounted electronic low vision enhancement system (eLVES). Invest. Ophthalmol. Vis. Sci. 2020;61(7):934.
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© ARVO (1962-2015); The Authors (2016-present)
Several eLVESs based on repurposed virtual and augmented reality head-mounted display systems are commercially available. All employ user-controlled uniform magnification over the full field of view (FFOV). We developed a virtual bioptic telescope (VBT) that magnifies only a region of interest on the display, with the size of the region and amount of magnification controlled by the user (only IrisVision incorporates the VBT). Our aim is to compare visual performance with VBT to that with FFOV magnification.
Reading performance (correctly read words per minute of IReST passages), visual motor performance (time to accurately trace Japanese characters with a stylus), and performance of visual information processing (psychophysical measures of facial expression discrimination – d’ using Karolinska Directed Emotional Faces) were obtained from 50 low vision subjects (BCVA≤20/60), half of whom were randomly assigned to FFOV magnification and the other half to VBT magnification, after being trained on the assigned eLVES and given 2 weeks of ad libitum use of the system at home. Subjects set the magnification and VBT size in the eLVES to their individually preferred values.
Mean reading speed is significantly faster for VBT than for FFOV magnification (Cohen effect size [ES]=0.59; p=0.008). Visual motor ability measures, estimated by Rasch analysis of tracing speeds of 20 different characters, is faster, but not significantly so, for VBT than for FFOV magnification (ES=0.26; p=0.23). There is no difference between FFOV and VBT d’ distributions of facial expression discrimination (ES=0.11; p=0.73).
This study is preliminary to a pragmatic comparative effectiveness study of the benefits of different image processing strategies in an eLVES that can be customized to the patient’s impaired vision and demands of the vision-dependent activity. The results suggest that reading performance with patient-selected magnification is better with the VBT than FFOV, which may be due to unmagnified preview areas with VBT. Visual motor performance also is better with VBT, but the ES is less than half the ES for reading, which is not statistically significant given the small sample size. There is no difference in facial expression discrimination between the two magnification strategies.
This is a 2020 ARVO Annual Meeting abstract.
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