1. [via Eurekalert EPFL] An estimated 285 million people are visually impaired worldwide. Age-related macular degeneration alone is the leading cause of blindness among older adults in the Western world. But this week at the AAAS Annual Meeting in San Jose, California, Eric Tremblay from EPFL in Switzerland unveils a new prototype of his telescopic contact lens–the first of its kind–giving hope for better, stronger vision. The optics specialist also debuts complementary smart glasses that recognize winks and ignore blinks, allowing wearers of the contact lenses to switch between normal and magnified vision.
The conference Abstract for the Smart Glasses and Telescopic Contact Lenses for Macular Degeneration is here. They plan to shortly enter clinical trials.
Inside the lens
The first iteration of the telescopic contact lens–which magnifies 2.8 times–was announced in 2013. Since then the scientists behind the DARPA-funded project have been fine-tuning the lens membranes and developing accessories to make the eyewear smarter and more comfortable for longer periods of time, and thus more usable in every day life.
The contacts work by incorporating a very thin reflective telescope inside a 1.55mm thick lens. Small mirrors within bounce light around, expanding the perceived size of objects and magnifying the view, so it’s like looking through low magnification binoculars.
Wink-controlled glasses
The researchers have also developed a novel method to electronically switch the wearer’s view between normal, or unmagnified vision and telescopic. This switching functionality is crucial for the lenses to be widely useful for non-AMD sufferers who will be able to have magnification “on demand”. In the system debuted at AAAS, electronic glasses use a small light source and light detector to recognize winks and ignore blinks. The wearer will wink their right eye for magnification, and left eye for normal vision.
There are glasses already on the market for people with AMD that have mounted telescopes, but they tend to look bulky and interfere with social interaction. They also do not track eye movement, so you have to position your eyes and tilt your head to use them.
The combination of the telescopic contact lenses and optional blink-controlled eyewear represent a huge leap in functionality and usability in vision aid devices and a major feat for optics research.
Retinal degeneration leads to blindness due to gradual loss of photoreceptors. Information can be reintroduced into the visual system by patterned electrical stimulation of the remaining retinal neurons. Photovoltaic subretinal prosthesis directly converts light into pulsed electric current in each pixel, stimulating the nearby inner retinal neurons. Visual information is projected onto the retina by video goggles using pulsed near-infrared (~900nm) light. This design avoids the use of bulky implants with power supplies, decoding electronics and wiring, thereby greatly reducing the surgical complexity. Optical activation of the photovoltaic pixels allows scaling the implants to thousands of electrodes, and multiple modules can be tiled under the retina to expand the visual field.
Subretinal arrays with 70μm photovoltaic pixels provide highly localized stimulation: retinal ganglion cells respond to alternating gratings with the stripe width of a single pixel, which is half of the native resolution in rat retina (~30μm). Similarly to normal vision, retinal response to prosthetic stimulation exhibits flicker fusion at high frequencies (over 20 Hz), adaptation to static images, and non-linear summation of subunits in the receptive fields. In rats with retinal degeneration, the photovoltaic subretinal arrays restore visual acuity up to half of its normal level, as measured by the cortical response to alternating gratings. If these results translate to human retina, such implants could restore visual acuity up to 20 / 250. With eye scanning and perceptual learning, human patients might even cross the 20 / 200 threshold of legal blindness. Ease of implantation and tiling of these wireless modules to cover a large visual field, combined with high resolution opens the door to highly functional restoration of sight.
Entirely new electronics have appeared in recent years, from epidermal electronic systems (EES) to soft and biocompatible micro robots to devices that dissolve in the body. These developments are still in their infancy, however, and can exhibit less than perfect performance. The Wearable Computing Lab is focusing on systems on plastic (SoP), which are deformable and implantable, energetically autonomous (zero-power), communicate wirelessly, and have numerous applications for sight and vision.
SOURCES – EPFL, AAAS, Stanford, Eurekalert
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