n developed countries, getting glasses is a simple matter: Visit an optometrist, get a prescription and have it filled at a corner store. Not so in the developing world, where there are few optometrists and little money for luxuries like eyeglasses.
Enter Joshua Silver, an atomic physicist at Oxford with a penchant for tinkering. “I like to experiment,” he said. “Take things apart and figure out how they work.”
In the 1980s, he began a do-it-yourself project making lenses whose focusing power could be changed by the user. He designed and built a liquid-filled packet made of two flexible transparent membranes — a liquid lens. Adding or draining liquid changes the curvature, making the lens stronger or weaker.
“I realized after a few months that I could make a very good lens — good optically, but not for glasses,” Dr. Silver said. “I started some dialogue with the World Health Organization and found the director of the program for the prevention of blindness. I asked him how many people in the world needed glasses and don’t have them. He said it was about a billion.”
Working with a British government grant, Dr. Silver developed a practical pair of adjustable eyeglasses. The two lenses are filled with clear silicone fluid, and there is a dial on each arm. The user puts on the glasses and then twists each dial until vision in both eyes is satisfactory.
The glasses do not correct for astigmatism, Dr. Silver said. “Many people, if you just correct their spherical refractive error, you get vision good enough to function.”
The glasses are not beautiful. The thick frames resemble those worn by Jean-Paul Sartre. But the dial and pump can be removed after adjustment. More than 30,000 pairs are in use by adults worldwide, and a study financed by the World Bank is testing a version for use by teenagers.
Dr. Silver is director of the Center for Vision in the Developing World, and his goal is to see a billion people wearing the eyeglasses they need by 2020. “We are trying to reduce the cost both by design and increased volume,” he said.
