It is very interesting to me that none of your vets are recognizing this condition. My 8-9 year old Golden Retriever had the same thing occur earlier this year. It started merely as seeing the flash of his inner or 3rd eyelid, until I realized that he was not blinking one of his eyes. He too would walk around with his eyes shut, clearly because it was annoying to him. He makes a very irritated groan when he's tired and I try to play with him, etc. and he started making that annoyed groan and then walking around with his eyes closed, sleeping more because of that, etc. 

Vet said - and was correct - that it was actually the entire left side of his face was numb. One of two things: 1) Hooper's Syndrome - which is just what the first sentence said. Not problematic, not resolveable, won't hurt him, but he might just lose muscle function in part of his face. 2) Bad Inner-Cochial Ear Infection. This is what it turned out to be. The drops he was giving and regular cleanings resolved the problem within weeks and he regained full control and returned to a normal blinker.