My opticians have always given me a microfiber whenever I got a set of glasses made, and last time I went I asked for a spare as well. Now I have the habit of having one in my pocket at all times so I don't have to devolve back to using the bottom of my tshirt.
Yeah, but the fabric of my shirt seemed noticeably worse at cleaning my glasses, so I stopped using that completely. Having a microfiber on hand at all times is very helpful for that
