Joshua Silver makes low-cost eyeglasses ($19) with self-adjusting lenses.
The glasses work on the principle that the more liquid pumped into a thin sac in the plastic lenses, the stronger the correction. Silver has attached plastic syringes filled with silicone oil on each bow of the glasses; the wearer adds or subtracts the clear liquid with a little dial on the pump until the focus is right. After that adjustment, the syringes are removed and the "adaptive glasses" are ready to go.
Silver hopes that his glasses will help those in developing countries who cannot afford glasses with ground lenses. (thx, owen)
