Father's Dementia

Well, my father's brain seems to be shrinking, or something.
He chooses to be completely out of touch with the world- will not watch the news or change the channel off of animal planet with no sound. He will however read science magazines and enjoy talking about their contents still, but I think that his eyesight may be going. I cannot imagine not being able to eat, see, or hear very well.
He stays holed up in his new small room, rarely venturing outside and when he does he's always surprised at how nice the fresh ocean air is.
I try to encourage him to go outside and sit but he comes up with an excuse and I don't press.
He has gotten a lot more feeble in the past few months-mostly because of just sleeping the days away I guess.