I have been periodically using something quite like an Optivisor (may even be an Optivisor brand unit) for about 15 years.

In my case it has been most valuable when soldering tiny SMDs on circuit boards.

While doing work on firearms, when I find that I need higher magnification I just put another pair of reading glasses ("cheaters") on over the ones that I am already wearing. That and bright light usually serve me well.