I've the same issue. My vision is bad enough that the diopter adjustment on Nikon bodies doesn't go far enough. There are diopter adjusters, though. I use an adapter to hold a round adjuster onto the square viewfinder. This lets me mount a rubber eyecup. When I go to shoot, I scoop my eyeglasses upwards onto my forehead, and see fine through the camera. When I'm done, I move the camera away from my face and shake my head so the glasses drop back down onto my nose.

If you have poor vision, particularly if you need bifocals or progressive lenses, consider that you do not need differing diopters to use the viewfinder: it's all at the same effective distance. This is obvious-ish if you have a mirrorless (EVF is all one screen), but also true for optical viewfinders.

So... if the diopter adjustment on your camera body works for you, consider getting an eyecup and start scooping. :-)