I'm curious if the vet has any idea what caused the vision loss.

Having a vision impaired kitty in the house will be new for you, Gary. At least, I think so; can't recall you ever writing about having one. I know for dogs, they learn their way starting from the water bowl. That is their reference point. So guardians of vision impaired dogs are advised not to relocate the water bowl. Should the dog ever get 'turned around,' it just makes its way to the water bowl, and starts off again. I'm not familiar with how this works for a cat. Perhaps you will want to search online.

The more obvious thing is not to move furniture. As she adapts, she will be back to jumping up on chairs and such. For some people, decorating for Christmas involves moving furniture. (Making room for a tree). Anyway, redecorating, relocating furniture, should be kept to a minimum.

Also keep the litter boxes where they have always been.

It's nice that she has lived with you when she could see well. This means she is already familiar with everything.