FuturePundit contemplates degeneration and repair as they pertain to our eyes: "Some people are content to grow old and even try to justify the changes which happen to our bodies as the various pieces break down. But this all seems like loss to me and with no compensating upside. The tiny muscles in your irises become less able to adjust pupil sizes and so your pupils can't dilate as far and as quickly to let in more or less light as needed. As far as I'm concerned this is yet another argument for treating the development of rejuvenation therapies as an urgent matter deserving a massive research push. ... Some labs are working on designs of artificial replacement lenses. Also, other labs are working on ways to grow natural replacement lenses using cells and tissue engineering. One way or another we'll some day be able to replace aged lenses with lenses as young as those of a baby. But we need much more in order to do eye rejuvenation. ... Further on down the road we'll eventually witness the development of tissue engineering technologies so advanced that they can grow whole organ replacement parts. Replacement eyeballs will then provide much more thorough and comprehensive solutions to the problems of aging eyes."