About 6 years ago I began to notice that from one day to the next the clarity
of my vision shifted.

Some days crystal clear. Other days, I might as well have not bothered
putting glasses on.

With the current pair of glasses (about 18 months old), the provider was very
generous. We had about 3-4 eye exams. Yet the glasses did not provide clear
vision. And the larger question remains, "what is the source of the variation?
"

I am not diabetic.
The night vision is crisp.
My father says he experiences the same thing.

I wore gas perm contacts until 4 years ago.

The question remains, "what is the source of the variation?"