My big boy has his inner lids showing all the time. Is this a sign of illness? He's pretty active and still plays hard with his little buddy. It seems unusual to see that membrane so much.
Third eye lid showing often indicates some kind of stomach or intestinal upset. Have you changed his food lately? Noticed any appetite changes, or difference in the litter box?
Any discharge from his eyes? Has the vet been consulted?
Thanks everyone for your advice. I did take Clancy to the vet and he was suitably impressed by his size. I thought he weighed around 20 lbs but is "only" 16.4 lb.
His eyes are OK, he is healthy. I mentioned the inner lid and the vet says he's fine.
FWIW, I have a cat with visible third eyelids as well. His eyes also pale blue and he is wall-eyed (opposite of cross eyes). Also nothing wrong with him, just looks strange - danged weird colour point genes.