Mobile emitter aside, does the Doctor only see through his holographically projected eyes? When he's in Sick Bay I would have assumed that there would be thousands of cameras and mics that he could see and hear through.
For that matter while I'm nitpicking the Doctor it seems wasteful to let him use the Holodeck solo. Activities involving him and others? Sure, fine. But anything renderable by the Holodeck can surely be simulated and streamed directly to his virtual brain (à la The Matrix) without needing to tie up the deck. In the ep where Tom and B'Elanna race the Delta Flyer the Doc traded a golf trip on the Holodeck with her and I got to wondering why the piece of software needs to be rendered expensively for solo activities.
For that matter while I'm nitpicking the Doctor it seems wasteful to let him use the Holodeck solo. Activities involving him and others? Sure, fine. But anything renderable by the Holodeck can surely be simulated and streamed directly to his virtual brain (à la The Matrix) without needing to tie up the deck. In the ep where Tom and B'Elanna race the Delta Flyer the Doc traded a golf trip on the Holodeck with her and I got to wondering why the piece of software needs to be rendered expensively for solo activities.