Interesting. I occasionally get something similar to that: I'll be watching tv and can hear and understand the words perfectly well, but don't understand the meaning of the sentences, even the short ones. Only lasts a few seconds, but I have to rewind to see what I missed.
Here's another pretty interesting article at that website about how the brain works.
I get that too. I have read about people having gone blind because of brain damage (where the optic nerve and eye are 100% functional) and report similar results.
I also think a lot of vision is subconscience. I am sure like me you have driven your car for miles and suddenly you look around and have no idea how you go to where you are.