Well, several companies have been growing diamonds with some success, so maybe we'll have diamond lenses one day. I wouldn't want to open the wallet for it though. Then we'll have the problem of how much resolution our brains can see
"As methods for growing diamond, both at high pressure and by chemical vapor deposition, improve, and as science finds ways to take advantage of diamond's properties, the potential applications of diamond's superlative properties appear boundless. From super electronics, to indomitable optical windows, to unscratchable surfaces - maybe the next watch bezel - diamond is an obvious choice."