Usually ocular pain causes closed eye.This problem can be involved one or both eyes.There are so many problems but most usual are:
1- Conjunctivitis : inflammation of the conjunctiva. Conjunctiva is the internal sensitive layer of eyelids. Any viral or bacterial infection, irritant materials and allergy can cause conjunctivitis.
2- Foreign body : penetrating or non-penetrating foreign body causes ocular pain and closed eye.
3- Corneal ulcer: any trauma to cornea causes painful eye.Cornea is a transparent thin layer which covers the eye globe.
4- Keratitis : any bacterial or viral infection of cornea causes inflamed painful cornea.
5- Keratoconjunctivitis: as it’s name shows this includes inflammation of conjunctiva and cornea together.The source of inflammation can be infectious or noninfectious.
6- Uveitis: inflammation of the components of eye globe is named uveitis.This disease can be infectious or noninfectious disease.
7- Eyelid paralysis: paralysis of the nerve which supports upper eyelid movement causes closed eye.
Needless to say that eye is a sensitive tissue and paying attention to any its abnormality and referring your pet to your vet as soon as possible can prevent from disaster.