"Stormin Mormon" fired this volley
in :

Do glasses change their focusss over the years? Does the focuss
change, if glasses are in storage?

No, Stormy, not unless they're plastic, and you get them _really_ hot...
and then they "warp"; they don't change focus 'gracefully'.

There are a lot of vision defects besides gross focus that might be at
play. You might have a very minor astigmatism. You may have a slight
clouding of the vitreous humor or the onset of cataracts. You might have
dried out corneae that makes looking at things like looking through
crinkled cellophane. You might have slight retinal damage from some
bright light or UV incident in the past.

You may also just be a victim of the fact that the eye itself changes
focus slightly during the day, and from times of good hydration to
dehydration.

The humors of the eye are 99.9% water. Reduce the water in your body,
and you change the concentration of water vs. proteins in the humors.
They change pressure, volume, transparency... and you "see" it as
glasses that aren't "strong enough".

I've found that most eye tests end up recommending a lens that is just a
bit too 'strong'. When the image you see goes from clear to SHARP and
more contrasty than before, the correction is too strong. That puts a
burden on the lens muscles. Whatever loss of flexibility you have in the
lens from age is then over-taxing those muscles even harder. They get
fatigued, and you "lose focus" both optically and mentally.

I go from doing long-range work with fireworks to close-up machining, to
CAD, to reading. The only solution I've found that handles all the tasks
well is a pair of glasses for each situation.

LLoyd