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Modification of a Head-Mounted Tablet Device for Reading in Low Vision
Published 2021 by Rebecca Deffler
Co-Author(s): Prathibha Srikantan, San-San Cooley, Gregory Hopkins, Brad Henry, Howell McCullough, Bradley Dougherty
Program Number: 215173
Article Type: Scientific Program
PURPOSE
The RealWear HMT-1[TM] is a head-mounted tablet with a camera and micro-display mounted to an adjustable arm, currently primarily used in industry settings. By modifying certain features, it may be useful for visually impaired people. The purpose of this study was to evaluate a modified version of the HMT-1 for reading with low vision.
METHODS
The HMT-1 camera and software allow for magnification and image enhancement. A custom Android application (Industrial Badger App[TM]) was used to modify the system, allowing increased magnification capability and text-to-speech conversion of printed reading material. Visual acuity and contrast sensitivity were measured with habitual correction and with the HMT-1. Critical print size with correction for test distance was compared to that with the device. A previously validated 300-word passage reading and comprehension test was performed with habitual reading aids, the HMT-1 with magnification, and the HMT-1 text-to-speech function. Subjects completed survey items on perceived benefits of the device. Paired t-tests were used for comparison.
RESULTS
Fourteen visually impaired subjects participated in reading testing. Mean habitual better-eye visual acuity with ETDRS by-letter scoring was 51 ± 10 (approximately 20/100), and improved to 80 ± 8 (approximately 20/25) when using the HMT-1 for magnification (p < .001 ). Average log contrast sensitivity was 1.47 ± 0.25, but decreased somewhat to 1.31 ± 0.27 when using the HMT-1 (p = .001 ). Critical print size with standard near correction was 3.1 ± 1.2 M-units and improved to 1.8 ± 0.7 with the HMT-1 (p < .001 ). Mean passage reading time was 162 ± 64 seconds with habitual device versus 290 ± 139 seconds for the HMT-1 camera (p =.001 ). Comprehension scores were worse with the HMT-1 camera compared to habitual and text-to-speech conditions. 77% of subjects reported the device to be useful, and 62% of subjects reported they would use the HMT-1 in real life.
CONCLUSION
An existing head-mounted tablet was modified for use by people with low vision. General acceptance and improvement in critical print size, despite increased reading times for long passages, supports use for spotting tasks. The size of the display is likely a limiting factor for prolonged reading, and additional modification of contrast may be required. Modifications developed may be beneficial to the visually impaired population in the industrial settings where RealWear HMT-1 is currently used, especially if maintaining working distance, peripheral vision, and mobility is important.
The RealWear HMT-1[TM] is a head-mounted tablet with a camera and micro-display mounted to an adjustable arm, currently primarily used in industry settings. By modifying certain features, it may be useful for visually impaired people. The purpose of this study was to evaluate a modified version of the HMT-1 for reading with low vision.
METHODS
The HMT-1 camera and software allow for magnification and image enhancement. A custom Android application (Industrial Badger App[TM]) was used to modify the system, allowing increased magnification capability and text-to-speech conversion of printed reading material. Visual acuity and contrast sensitivity were measured with habitual correction and with the HMT-1. Critical print size with correction for test distance was compared to that with the device. A previously validated 300-word passage reading and comprehension test was performed with habitual reading aids, the HMT-1 with magnification, and the HMT-1 text-to-speech function. Subjects completed survey items on perceived benefits of the device. Paired t-tests were used for comparison.
RESULTS
Fourteen visually impaired subjects participated in reading testing. Mean habitual better-eye visual acuity with ETDRS by-letter scoring was 51 ± 10 (approximately 20/100), and improved to 80 ± 8 (approximately 20/25) when using the HMT-1 for magnification (p < .001 ). Average log contrast sensitivity was 1.47 ± 0.25, but decreased somewhat to 1.31 ± 0.27 when using the HMT-1 (p = .001 ). Critical print size with standard near correction was 3.1 ± 1.2 M-units and improved to 1.8 ± 0.7 with the HMT-1 (p < .001 ). Mean passage reading time was 162 ± 64 seconds with habitual device versus 290 ± 139 seconds for the HMT-1 camera (p =.001 ). Comprehension scores were worse with the HMT-1 camera compared to habitual and text-to-speech conditions. 77% of subjects reported the device to be useful, and 62% of subjects reported they would use the HMT-1 in real life.
CONCLUSION
An existing head-mounted tablet was modified for use by people with low vision. General acceptance and improvement in critical print size, despite increased reading times for long passages, supports use for spotting tasks. The size of the display is likely a limiting factor for prolonged reading, and additional modification of contrast may be required. Modifications developed may be beneficial to the visually impaired population in the industrial settings where RealWear HMT-1 is currently used, especially if maintaining working distance, peripheral vision, and mobility is important.
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