My grannys dog barkes at his owner when he is out side and he barks at people in the house as well bun they think he might have bad eyesight can u do any think for a dog that has bad eyesight can the vet look at his eyes or what ?

Yes the vet can look at his eyes.
How old is he?
Does he also bump into things?
Or walk slower as if he doesn't quite know where to go?
Or is it only that he is barking at people?

The vet can look at his eyes to tell you if his eyesight is bad, but there's nothing that the vet can do to correct bad eyesight.

Older dogs often start to lose their vision, just like people. But, unlike people, they can't get glasses, or contacts, or have lasik surgery.

Most dogs learn to work with their failing eyesight.