I think heavy metals play a big part in this. As they do in MANY MANY other health issues.
I stopped using aluminum based deodorant almost a year ago, and my vision is eagle eye sharp now(floaters are also less noticeable).
Mind you.. I have a very aggressive supplement/vitamin/mineral regimen.
I believe that omegas and Vit d play a huge role also. As well as high dose magnesium + Iodine supplementation.