6 links have been added on 2 ideas about #seeing.
  1. The lenses can break easily so I suggest reading this first

  2. You can do this with some frame types but it depends on the design. Here is a guide to the types that allow you to do so.

  3. Took years but I think these are on their way to the market now.

  4. Been patented, not sure if the idea has been done, especially to allow your glasses to focus on whatever your eyes are focussing on.