The World Health Organization estimates that over half a billion people around the world need vision correction, but have minimal access to trained eye-care specialists and affordable eyeglasses. The majority of these people live in the developing world, on less than two dollars a day. The educational and economic impact of uncorrected vision is profound, limiting people’s ability to read, write, learn, work, and participate actively in daily life. In 1996, Joshua Silver, a physicist at the University of Oxford, created AdSpecs to offer low-cost corrective eyewear to underserved patients, who can “fill” their own prescription without the need for expensive optical equipment. A few years later, Silver introduced a prototype of his self-adjustable glasses, which he developed for small-scale mass production. In 2007, he added a lens power scale, an important feature to allow a user to know their prescription.
The glasses’ technology is simple: as the curve of the lens changes, so does its refractive power. Silver created fluid-filled lenses—a clear, circular sac of silicone oil, which has a high refractive index, is sandwiched between two clear and durable plastic membranes. The lenses are connected to a tube and a small syringe fitted with a dial, which wearers use to adjust the amount of liquid in each sac, custom forming each lens’s curvature to their prescription. Once adjusted, the sacs are sealed off with a small valve and the syringes are removed. The technology can correct nearsightedness and farsightedness, but not astigmatism, and the lenses can only be circular. Currently priced at $19 a pair, the glasses demonstrate how a low-tech solution can bring costs down and allow for easy deployment of a health device. Silver hopes that with his self-refraction approach, half a billion people will be wearing the eyeglasses they need by 2020.Location: united kingdom