Your eternal loop theory is addressed in Lee Strobel's book by experts. Have you taken the time to read that one book, or are you simply grabbing at esoteric theories so you can simply argue with scientific facts?
Bad eyes have existed in all animals for centuries. So it appears that natural selection has failed throughout the animal kingdom for centuries. Decay in vision is the product of aging, not natural selection. I have worn glasses since I was about 13. Over the years my eye have gotten worse and then for a period of time they actually improved since the perscription for my glasses was weakened and then a couple of years later strenghthened.
Is natural selection reducing the gene pool, or are those genes simply becoming recessive genes and are still available? You cannot show your statement to be true. Have you ever seen a rose bush revert to the colors it was developed from? I have, it happens when a patented rose gets older. The same bush will produce roses of different colors, so the recessive colors become dominate in one or two blossoms on the same stem.