I divested myself of all scales but 1/60th(25mm-28mm) long before my sight became an issue.
BattleTech was the first to go when I sold two full Battalions plus a Company of Mechs with their supporting infantry/AFVs and Auro-space support.
Next out the door was my Ogre/Gev collection (to someone on TMP as a matter of fact:D)
Then Mech-Warrior Dark-age(four armies worth)sold to a single buyer and then a tiny force of Epic Space Marine stuff(just bought it really, to see if I could convert and scratch build in 6mm. I did and they turned out really nice but did not hold my interest)
I tried 15mm many decades ago with some ECW miniatures but the sculpts were very dumpy and thick. Now I think I wish I had been more patient with 15mm models as they have gotten way, way better over the years. Now I am just to well vested in 28s to go back and I have zero desire to do multiple scales.
The only thing I kept that is not 1/60th are my original CAVs from Reaper as they are pretty large and I love the older version of the game. Those and my Epic scale GW Titans. The Eldar Titans got drafted into my Craft-world armies as Wraithlord Dreadnoughts and my Imperial Titans found new lives as assault and fire support Cyborgs for 1/60th scale science fiction games, mostly Kryomek.
I still have the 20 mm Franco-Prussian war stuff my dad and brother did plus the WWII Armies he did and I added to. None of them have been out of boxes for many decades other then for me looking at them. I hope someday to find them happy homes as I don't do historical war gaming anymore.(sort of to many not so happy memories there)
Anyway, that seems a very long answer to the OP question, but ….there it is. :)