Magnification on Headsets Challenges Visually Impaired

Laird Harrison

May 08, 2020

First-generation headsets helped magnify objects and increase contrast for people with impaired vision, but they also encouraged head movements that degraded visual performance and prompted motion sickness.

A redesign by IrisVision of its commercially available headset is aimed at fixing these problems, but new research suggests that the path to success will not be straightforward as patients adjust.

The concept of head-mounted devices dates back to the 1990s, but many products have recently come onto the market to assist people with low vision. "Since the entertainment industry has taken on the virtual-reality systems, hardware components have dropped in price," explained Ashley Deemer, OD, from Johns Hopkins University in Baltimore. "Small cameras have improved. That's what spurred the resurgence."

The Samsung virtual reality software that is part of the IrisVision headset allows a virtual bioptic telescope to create a circle of magnification — a bubble — in the center of the field of view. This means that the user can look at magnified objects against a background without magnification in the center of a 57.4° field of view. The previous version of the device magnified the full field of view, reducing it to 33.0°.

Deemer presented interim data from the first phase of the eLVES crossover study — looking at whether people with low vision would use the magnification bubble feature of the head-mounted device — at the virtual Association for Research in Vision and Ophthalmology 2020 Annual Meeting,

The new feature expands the field of view provided by the device, but it might have made it less intuitive, said Deemer.

"What I suspect is that sometimes when patients are a little bit older, they might be averse to some of the technological advances, and when they put it on, they may be hesitant to use some of the more advanced modes," she told Medscape Medical News.

Further training might result in greater use of the advanced features, she suggested.

eLVES Crossover Study

In the study cohort, best-corrected visual acuity (BCVA) was less than 20/64 in the better-seeing eye of the study participants, and mean age was 62 years. There was no difference in age or BCVA between the 19 people randomly assigned to the low-vision enhancement system with the bubble feature and the 20 who were assigned to a legacy version of the device without the bubble feature.

After 30 to 45 minutes of training, participants were sent home and encouraged to use their devices in their daily activities for 2 to 4 weeks. A sensor tracked usage.

On average, participants in the bubble group used their devices less than those in the legacy group, although the difference was not significant (P = .145). And most use in the bubble group did not involve the magnification bubble.

Both devices were most commonly used in "scene" mode, which provides a simple magnification of the field of view. However, average daily duration of use in scene mode was significantly shorter in the bubble group than in the legacy group (5.76 vs 27.17 min; P = .016).

Participants rarely used the regular "reading" mode, which magnifies black letters on a white background, or the "snapshot" mode, which freezes an image, allowing users to scan the image at their own pace.

In the ongoing eLVES study, 100 participants will crossover from one device to the other, which could reveal whether a handful of outliers skewed the results in favor of the legacy device.

I think with time they will become smaller, they will become lighter, they will become sexier, and they will become cheaper.

When Deemer and her colleagues asked participants about overall satisfaction, 26% said they would definitely use a device (enhanced or legacy) in an anonymous public gathering, and 33% said they would perhaps use it.

In contrast, 54% said they would definitely use it in an intimate private gathering, and 26% said they would perhaps use it.

In addition, 72% would definitely recommend the device to a friend, and 23% would perhaps recommend it.

The bubble offers a real advantage, but Walter Wittich, PhD, from the University of Montreal, said he can see why some people don't embrace this feature immediately.

"At the edges of the bubble, you have this transition area where you go from the magnified area inside the bubble to the unmagnified periphery," he told Medscape Medical News. "So you have a little bit of image distortion around the bubble, and as you move the camera, or vision, direction, it creates a perception of movement inside this distortion."

"It takes a bit of time to get used to," he explained.

In a previous analysis Deemer was involved in, the magnification bubble was shown to significantly improve the ability of users to carry out tasks of daily living, such as cooking a meal and managing finances.

However, because the device changes the entire field of vision, it is not suitable for use while walking or driving.

"That's an ongoing challenge for many of these devices," Wittich said. "In a perfect world, you would have one device that you can use everywhere. We're not there yet."

But the technology is rapidly improving and there are already valuable tools for people with many low-vision conditions.

"I think with time they will become smaller, they will become lighter, they will become sexier, and they will become cheaper," Wittich said.

Association for Research in Vision and Ophthalmology (ARVO) 2020 Annual Meeting.

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