A glow-in-the-dark contact lens could help stave off blindness in the hundreds of millions of people who suffer from diabetes across the globe.The newly developed contact lens may be a potential solution for diabetic retinopathy.
Developed by Cook, along with a group of researchers from the lab of Yu-Chong Tai, Caltech’s Anna L. Rosen Professor of Electrical Engineering and Medical Engineering,the lens works by producing just enough light to reduce the retina’s night-time oxygen demand by giving the rod cells the faintest amount of light to look at while the wearer sleeps. The lenses thus reduce the metabolic demands of the retina.
Early testing of the lenses conducted in collaboration with Mark Humayun’s lab at the University of Southern California is showing promising results, with rod cell activity reduced by as much as 90 percent when worn in the dark
The vials, which are only the width of a few human hairs, are implanted in the lens in a radial pattern like the rays of a cartoon sun. The vials create a circle that is just big enough to fall outside of the wearer’s view when the pupils are constricted in lighted conditions. In the dark, the pupil expands, and the faint glow from the vials can illuminate the retina.
Until now,Diabetic retiniopathy was treated by using a laser to burn away the cells in the peripheral parts of the retina, so the oxygen those cells would have required can be used by the more important vision cells in the center of the retina. Another treatment requires injecting medication that reduces the growth of new blood vessels directly into the eyeball.
Cook hopes his contact lenses will offer a solution that patients will be more willing to try because of the minimal effort and side effects.
Like the laser treatment, the lenses reduce the metabolic demands of the retina, but in a different way. The rod cells present in the eyes provide vision in low-light conditions. The rod cells need and use a lot more oxygen in the dark than with light.
“Your rod cells, as it turns out, consume about twice as much oxygen in the dark as they do in the light,” Cook says.
For that reason, the contact lenses are designed to reduce the retina’s night-time oxygen demand by giving the rod cells the faintest amount of light to look at while the wearer sleeps.
“If we turn metabolism in the retina down, we should be able to prevent some of the damage that occurs,” he says.
To provide light to the retina throughout the night, the lenses uses technology from wristwatches that have glowing markers on their faces. The illumination is provided by tiny vials filled with tritium, a radioactive form of hydrogen gas that emits electrons as it decays. Those electrons are converted into light by a phosphorescent coating. This system ensures a constant light output for the lifetime of the contact lens.
Lighted sleep masks, used earlier showed poor results because patients had difficulty tolerating the masks and ignoring the light shining into their eyes as they slept.
The sleep mask light source is not affixed to the eye, so as the eye moves, the wearer sees a flicker and that’s very distracting as you’re trying to fall asleep, he says.
Cook says his lenses avoid that problem by placing the light source on the surface of the eye, so when the eye moves, the light source moves with it, and there is no flicker for the wearer to notice.
“There’s neural adaptation that happens when you have a constant source of illumination on the eye. The brain subtracts that signal from the vision and the wearer will perceive dark again in just a few seconds,” he says.
The contact lens design also ensures that the retina receives an appropriate dose of light throughout the night.
“As we sleep, our eyes roll back. For a sleep mask this means the eye is no longer receiving as much light, but the contact lenses move with the eye, so there is no such problem,” he says.
The team recently took their invention to TigerLaunch, an entrepreneurship competition hosted by Princeton University. Their work was recognized as the top medical technology, and the team came in third place overall.