The idea that light behaves differently when passing through different media, and that this could be used to influence vision positively, is not a new one. As early as 1000 AD, glass spheres were being used as magnifying lenses. That said, it should be noted that early experimenters with optical devices in direct contact with the eye were not primarily interested in correcting defective vision, but were concerned with noting either the effects of different media upon light, or the different mechanisms of human vision such as focusing.
The first proposals which did involve correcting eyesight included that of Rene Descartes, whose idea of liquid-filled test tubes placed directly on the cornea (the domed part of the eye) sadly did not take into account the necessity of blinking. Two hundred years later, Sir John Herschel (lauded for his contributions to astronomy, optics and photography) noted the likeliness of impressing the shape of a cornea onto a transparent medium as a plausible method for ocular improvement. It then took only fifty years for this suggestion to be realised in the form of glass lenses.
Such lenses were heavy and uncomfortable and could be worn for no more than a couple of hours at a time. They did not make full contact with the eye, but rested on the less sensitive whites of the eye, the gap between the lens and the cornea being filled with a suitable solution such as tears. These types of lenses are still used today as a necessity for some eye conditions and for film or television use (to make cool effects such as turning your eyes all white or all black, and all the variations in-between).
It wasn’t until the late 40s that the first corneal mounted lenses appeared, helped by the development of plastics, but it took another ten years before soft contact lenses could be developed. All the types of lenses mentioned in this article initially suffered from their lack of oxygen permeability but over the past few decades the materials sciences have largely eradicated this problem.
Plans for the future include the development of the so-called bionic lens, which features integrated circuitry that can deliver a ‘heads-up display’ onto the lens and thus provide graphics layovers for our vision. That Google are already displaying prototype glasses with this type of feature (though of course not built in remotely the same way) would seem to indicate that such refinements are merely a matter of time and the basic idea has been implemented and tested with positive results. Such devices would also take advantages of the eye’s natural blind spots and use such areas to integrate more circuitry.