Some Vets are now specializing on Cataract surgery for dogs, much like it is for humans. They cut out the lens, and insert an artifical one. The only problem with older dogs is the danger of anesthesia. You would need to discuss the possibilities with your Vet.

Remarkably dogs can navigate a little with sensory perceptions from their whiskers.

P.S. You can still play puppy games through smell. It's called "hide the treat" game. The sense of smell for a dog lasts throughout its life.