50-year glasses

As anyone who wears glasses knows, vision changes over the years. Therefore, one has to have one's eyes rechecked and buy new glasses every couple years. I have two solutions to this problem: 1) A pair of glasses with two lenses per eye; one lense is fixed, the other can be adjusted like the zoom on a camera. 2) the glass/plastic lense is replaced with a transparent rubber-like material suspended on fine threads in the frame. This rubber lense is deformed, similar to the lense in a human eye, by turning a small knob on the side of the glasses which tightens the thread. In this way, the need for new glasses is eliminated, as one just turns the dial until the world can be seen clearly. These would also eliminate the need for reading glasses and the like, as you simply turn the dial knob back for reading, then forward again for everything else.