A newly launched mobile eye-test device could lead to prescription virtual-reality screens. After five years of development and about 40,000 tests worldwide, the smartphone-powered eye-test devices developed by MIT spinout EyeNetra is coming to hospitals, optometric clinics, optical stores, and even homes nationwide. But on the heels of its commercial release, EyeNetra says it’s been pursuing opportunities to collaborate with virtual-reality companies seeking to use the technology to develop “vision-corrected” virtual-reality displays.“As much as we want to solve the prescription glasses market, we could also bring virtual reality to the masses,” says EyeNetra co-founder Ramesh Raskar, an associate professor of media arts and sciences at the MIT Media Lab who co-invented the device.
The device, called Netra, is a plastic, binocular-like headset. Users attach a smartphone, with the startup’s app, to the front and peer through the headset at the phone’s display. Patterns, such as separate red and green lines or circles, appear on the screen. The user turns a dial to align the patterns and pushes a button to lock them in place. After eight interactions, the app calculates the difference between what the user sees as “aligned” and the actual alignment of the patterns. This signals any refractive errors, such as nearsightedness, farsightedness, and astigmatism. The app then displays the refractive powers, axis of astigmatism, and pupillary distance required for eyeglasses prescriptions.
In April, the startup launched Blink, an on-demand refractive test service in New York, where employees bring the startup’s optometry tools, including the Netra device, to people’s homes and offices. In India, EyeNetra has launched Nayantara, a similar program to provide low-cost eye tests to the poor and uninsured in remote villages, far from eye doctors. Both efforts used EyeNetra’s suite of tools, now available for eye-care providers worldwide. According to the World Health Organization, uncorrected refractive errors are the world’s second-highest cause of blindness. EyeNetra originally invented the device for the developing world specifically, for poor and remote regions of Africa and Asia, where many people can’t find health care easily. India alone has around 300 million people in need of eyeglasses.But the United States has offered the best market, in terms of adoption, Raskar says. “The consumerization of health is happening much faster here in the U.S. than in the developing world,” he says. “If you’re to play that role of smartphone-based personalized health solutions, then we have an amazing lead over anyone else.”
Over the past six months, EyeNetra has been in discussion with virtual-reality companies to integrate the technology into virtual-reality displays, Raskar says. The idea, he says, is to use the startup’s technology to develop custom screens to fit a user’s eyeglass prescription. Prescription screens could make virtual-reality devices more form-fitting for a more immersive and comfortable experience, Raskar says, Right now, devices are built with extra space on the viewing end for people wearing glasses. But it could also help solve a larger issue which is aligning the eye lens, prescription lens, and the virtual-reality screen. “All three have to be aligned in the right way for you to enjoy the experience,” Raskar says. If the glasses shift, for instance, optical aberrations disrupt the viewing, potentially causing headache, fatigue, and nausea. EyeNetra’s technology measures how a user’s optical refractive errors will affect how they see patterns on a digital display in an environment very similar to a virtual-reality headset, Raskar says. Therefore, companies could use these precise measurements to display images that are pre-corrected to a user’s specific refraction errors. “It’s personalized correction,” Raskar says. “Your [vision] correction is built into the headset.”
The device was designed as an inverse of a traditional Shack-Hartmann wavefront sensor machine, which shines a laser into the patient’s eye and measures the refracted light with a photon sensor to find optical aberrations that affect eyesight. Essentially, Netra replaces the expensive sensor with a smartphone display. Because the red and green light goes through different parts of the eye, aligning the two colors similarly demonstrates any optical aberrations.
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