A cat's eyes, which lend charm and personality, are also subject to several diseases.
Congenital eyelid disorders may include the absence of an upper eyelid or entropion : inward turning of the eyelid causing the eyelashes to scratch the cornea and creating lesions. Surgery is required to correct these conditions. Blepharitis, infection of the eyelids, is caused by bacteria or fungi (ringworm).
The eyes are lubricated by tears. Insufficient tear production can lead to serious eye conditions, such as keratoconjunctivitis sicca.
Tears drain from the eyes through narrow lacrimal canaliculi (ducts), which sometimes become plugged as the result of infection or a congenital deformity. If tears do not drain properly, they flow down the sides of the nose leaving brownish markings.
Conjunctival diseases are common in cats. They are often one of the symptoms of a more general disease and are one of the early symptoms of chlamydiosis. The herpesvirus of infectious rhinotracheitis is responsible for a mucuslike, pussy discharge as well as keratitis punctata or serious corneal ulcerations, either during the acute stage of the illness or as a chronic condition following the primary infection.
Cat's sometimes develop corneal lesions that are unique to the feline species, such as corneal sequestrum, characterized by the formation of a blackish plaque on the corneal surface.
Uveitis causes the coloration of the iris to change. The iris becomes dull and pinkish, and the surface becomes hazy and rough. There are three types of uveitis specific to cats. They are part of the clinical presentation of feline leukemia, feline immunodeficiency virus, and feline infectious peritonitis. Uveitis may also appear in cases of toxoplasmosis, trauma, or eye infections.
Glaucoma, an elevation of intraocular pressure beyond normal levels, increases the volume of the eye and causes extreme pain.
The integrity of the retina is essential to good vision. Hemorrhages within the retina and retinal detachment may appear following trauma or serious illness. These two conditions are also complications of uveitis. Retinal degeneration caused by taurine deficiency is no longer an issue, since commercial foods now contain adequate quantities of this essential amino acid. Dog food does not contain sufficient quantities of taurine, therefore it is not appropriate to feed cats dog food.
Finally, cats may also suffer from four nervous disorders affecting the eyes: Strabismus, third eyelid prolapse, Horner's syndrome (contraction of the pupil in one eye and prolapse of the third eyelid), dilated pupil syndrome, and feline dysautonomia.
Prolapse of the Third Eyelid: The cat has a third eyelid located at the inner corner of the eye. It helps protect the eye and distribute tears to protect the cornea. Sometimes, this third eyelid remains continuously visible for a variety of reasons:- Mechanical causes related to the condition of the eye - microphthalmos (abnormally small eye) or atrophy of the eyeball, extreme weight loss, tumors, or trauma to retractor muscles caused by a scratch.- Neurological causes irritating the area or disrupting equilibrium, an overactive parasympathetic system, or following an abdominal condition.- Lesion of the cervical sympathetic nerves caused by a variety of conditions, including a herniated disc, otitis, a tumor, an abscess, or trauma.
In cats, most cases of prolapsed third eyelid follow an abdominal disorder. This is why the veterinarian is particularly interested in the health of the cat's digestive tract and often prescribes a laxative (for hairballs), a dewormer (undetected dipylidium tapeworm infections often produce this type of symptoms), or an intestinal antiseptic.
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