The possible causes for your cat’s eye staying consistently closed range quite significantly.
The problem could be as simple as a foreign object that has entered the eye, just like what happens to humans.
On the other hand, it could be a sign of a more severe and complicated pause.
Just like humans, older cats sometimes suffer from cataracts. This is often due to the onset of a disease like diabetes. It also usually features inflammation of the uvea, which contains the iris part of the eye.
Cat eye infections are relatively common. They can be caused by bacteria and result in conditions like conjunctivitis. You may need to consult a vet because the condition could also be viral.
Corneal ulcers sound painful and are a slightly more involved condition. The corneal layers of the eye have been depleted, and further damage may be caused by trauma.
Keratoconjunctivitis sicca (KCS), or dry eye, is an unfortunate condition where your cat’s eyes are not producing enough tears to clean the eye routinely and naturally.