I may be of use to write the letter names of the notes, or of some of them, above or below the staff?
If bigger sheet music don't work, you can try my method, since my eyes also nearly same condition with your eyes (mine even plus cylindrical eyes)Try to read it on sections, maybe each 3 or 4 bars, marked by pencil. Or 'newbie' way, write the note on alphabetical (like mark 'F#', Bb, dll) on notes which hard to be read (can be read slowly due of your eyes condition).For the first time maybe it can take long progress, but later you'll know and able to read those hard notes.Maybe like on the pic
Yes this helps a lot! I've done a few here and there and the next parts (where its not written on top) I already remember where the notes are. Making great progress already. About the vision..yeah, I've noticed its not only with music sheets, my eyes seem to get tired quickly when reading small letters, kind of what I feel with the lines and notes.
I also found this site https://www.sightreadingpractice.com/cgi-bin/index.cgi?sight&layout=full&id=17067895013&dpt=s&split=2 which is great for training!
I also found this site https://www.sightreadingpractice.com/cgi-bin/index.cgi?sight&layout=full&id=17067895013&dpt=s&split=2 which is great for training! Specially when you are not home, it works great on mobile devices with a compatible browser and touchscreen. Every now and then I find myself chasing notes around with that amazing tool haha!
Yeah, glad it's help But don't use my advice too much, because you can lack on reading composition (if you take ABRSM exam, reading sight will be a difficult test for you), and you'll have a bad time if you use my advice on higher level works like Liszt, Chopin, or Rachmaninoff.