Dogs don’t compare himself/herself with other dog, and the past and current.
When I see a full-vision dog’s behavior such as catching a tossed treat, running happily, and holding/playing a toy with giving other dog a proud look, I feel what it means to have adequate vision.
Even now I’m still sometimes sorry for my blind dog Nono and feel sad because she has what she can do and enjoy fewer than full-vision dogs. So I assume that people feel really helpless or give up hope when they know that their dog went blind or will go blind.
But don’t forget that the feelings is your own feelings. Your dog doesn’t think so, and feel so.
Dogs don’t compare himself/herself with other dog, and the past and current. They might not want to be pitied. Your dog just want to enjoy the current moment!
If you can notice that, you might find out what you should focus on and do. We can help our dogs enjoy life whether they are blind or not.