Our patio door has a dog door built in. When he's locked out, Eddy will somtimes come check the door to see if he can get in. If I stay perfectly still he can't see me. I can be standing right next to the door and he just looks right past me if I stand still.
I know he isn't going blind because he'll chase a cricket and can see bird hiding in the grass outside his fence. He's just a weirdo.
Re: Also, my dog is a T-rex
I think the reflection hides me unless I move.