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Ashley Deemer, James Deremeik, Robert W Massof, Chris Bradley, Kyoko Fujiwara, Frank S Werblin, Bonnielin K Swenor; Evaluation of a Virtual Bioptic Telescope and Virtual Projection Screen for Low Vision Patients. Invest. Ophthalmol. Vis. Sci. 2018;59(9):2563. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Magnification is used in low vision rehabilitation to compensate for reduced visual acuity. Using digital image processing, we tested the effectiveness and utility of two innovative approaches to magnification: a virtual bioptic telescope and a virtual projection screen in a head-mounted display (HMD) equipped with a high-resolution video camera and head trackers (Iris Vision, Visionize LLC). The aim of our study was to determine if these new image processing approaches to magnification are beneficial to low vision patients for performing everyday activities.
A total of 30 participants with best corrected visual acuity <20/100 in the better-seeing eye and bilateral central scotomas were recruited. The participants were trained on the HMD system in-clinic, then completed a 7-10 day in-home trial, but instructed not to wear the device for mobility. The Activity Inventory (AI) was administered before and after the home trial to measure the effect of system use on self-reported visual function. A simulator sickness questionnaire and a system-use survey were administered. Baseline and follow-up AI results were analyzed using Rasch analysis.
Significant improvements were seen in visual ability measures estimated from goal difficulty ratings (Cohen’s d=0.79, p <0.001), as well as reading (d=1.28, p<0.001) and visual information (d=1.11, p<0.001) functional ability estimated from difficulty ratings of corresponding subsets of tasks. There was no improvement in visual motor function or mobility. Five patients (17%) reported headaches and four (13%) reported symptoms of nausea while using the system. Twenty-three (77%) suggested the battery life could be improved and 11 (37%) suggested the touchpad controls could be improved. Ten (33%) suggested a rectangular rather than a circular magnification window, especially for reading. In assessment of willingness to pay, 75% of patients would not exceed $2500. The average patient rating of the system’s utility on a scale of 1 to 10 was 7.14.
Based on the AI results, we conclude that use of the system results in functional vision improvements in reading and visual information processing (i.e. seeing faces, watching television). The lack of improvement in mobility and visual motor function is most likely due to limited field of view (70ox40o), poor depth perception and lack of binocular disparity from the cyclopean view.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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