
I had the same worry with a large litter of Yorkshire Terriers a couple of years ago. One pup opened eyes on day 13, 2 on day 14, and 2 on day 15. I started getting really concerned when the 6th pup did nothing. I made an appointment to see the vet on day 17.
By this time I had all sorts going on in my head. The eyes weren't gummed up - and I thought "what if there are no eyes?"
I had (in my mind) decided that I would ask the vet if pup should be PTS. Arrived home from work, all ready to go to the vet. Picked pup up and looked at his sweet face with sadness. He quite blatantly opened his eyes - blinked hard and fast, and said "Gotcha!" :-)
He didn't really speak! :-)