Allow me one sentiment before answering the technical part of his question. As a concerned client with a sick pet, it is always good to ask questions, no matter how foolish you may think the questions are. If something puzzles or bugs you, then get that resolved by the person who put that concern into you.
Now on to your question. It is common to use artificial lenses in human cataract surgery, but not so in animals, particularly dogs. The canine immune reaction is much stronger in any ophthalmic surgery then it is in human beings. Scarring is a major concern to the the vet eye surgeon, and if an artificial lens were placed, the very real possibility of blindness brought on by surgical scarring is manifest.
Certainly in the future there will be material improvement in artificial lenses that would allow implantation without scarring, but we are not there yet. Dogs do not rely on fine focusing such as is required in reading, threading a needle, etc. Dogs rely on movement and intermediate field of focus. Distance and close vision is good, but not essential. Ever notice how dogs are very keen on dealing with rabbits,deer,cats/etc/ whenever these are flushed from cover, and how the dog will pursue them? And yet that same dog will easily pass by a still little beastie that may or may not be hidden.
Once the lens is removed, this leaves the dog with intermediate field of focus. Your dog will still be able to fetch a ball, and this has been demonstrated in many eye patients post-operatively. Now it is not realistic to think that your dog can fetch a small ball thrown half a kilometer, but certainly five to ten meters.
Reminds me of the old joke: the patient asks his doctor, "Doc, can I play guitar after the shoulder surgery?" Doc answers, "Sure, why not?", patient answers, "Because, Doc, I couldn't play anything before".
Dr. Van Lienden
Dr. Raymond Van Lienden DVM
The Animal Clinic of Clifton
12702 Chapel Road, Clifton
Virginia, U.S.A. 20124