New dog

It has been proven in studies that you can teach old dogs new tricks so teaching your dog to do his business outside can still be done. I know your new dog does not see very well but unless he has trouble physically moving he still needs his exercise. Dog's need guided exercise/walking to maintain their health. You can try to slowly walk him around the yard with a leash on. Wandering around an area without a purpose is not the same thing as my Vet had explained to me before. I also thought that a yard to play in was enough exercise for my dog too.