kitten eyes

I foster mama with 7 kittens. They are 11 days old today and their eyes are still shut closed. All resources say their eyes should be wide open by day 10. I found that long-haired kittens open their eyes later 10-14 days. Well, mama is very shorthair, she is not even fluffy. The father of course could be longhair, who knows. Just wondering what is your experience with that matter?

I foster litters a lot.  I only worry if their eyes are not open by day 14- I've never followed a one week or 10 day rule.  This is based only on personal experience though, not veterinary or medical knowledge. I also worry slightly if all of their eyes have been open for several days and only one kitten has not opened theirs, but still usually take no action till day 14.

OK, thanks