Simplicity is often the key to a great invention, and that's at the core of this idea from a retired physics professor: Adaptive eye-glasses that are easily tweaked to suit the wearer.
Joshua Silver's invention has flexible liquid-filled layered lenses instead of conventional solid glass or plastic ones. When being "fitted" to a particular wearer the attached syringe is used to insert just the right amount of optical liquid into the flexible sack inside each lens. This changes its shape, adjusting the focal-length of the whole lens assembly so it properly corrects an individual's poor vision. The syringe is then removed, and the glasses act exactly like conventional ones.
The frames are toughened to resist bumps and knocks the glasses will likely suffer in their target market: developing nations, where finding an optician in remote areas is difficult, or requires travelling long distances to a city. A trial project has been successful, and now the scheme is ready to be rolled out properly: first in India. The ultimate aim is to reach 100 million people with poor sight each year.