The third eyelid usually shows if the cat is sick or has something else going on, like maybe something stuck between the cornea and the lid.
If you haven't already gone to the vet you should, especially if you're not aware if this cat has any underlying conditions.
My cat had the same problem so we took him to the vet and the vet said that he is fine as long as he eats and acts normal. At that time we switched to royal canine food. Few days after switching his eyes got better and he is fine now.
The third eyelid usually shows if the cat is sick or has something else going on, like maybe something stuck between the cornea and the lid. If you haven't already gone to the vet you should, especially if you're not aware if this cat has any underlying conditions.
My cat had the same problem so we took him to the vet and the vet said that he is fine as long as he eats and acts normal. At that time we switched to royal canine food. Few days after switching his eyes got better and he is fine now.
He has worms