Eyes

Eye trouble that can occur in the Cavalier King Charles Spaniel:

RETINAL DYSPLASIA (RD)
Retinal dysplasia is an eye disease affecting the retina. It is usually a nonprogressive disease and can be caused by viral infections, vitamin A deficiency, or genetic defects. Retinal dysplasia is characterized by folds or rosettes (round clumps) of the retinal tissue.

Most cases of retinal dysplasia in dogs are hereditary. It can involve one or both retinas. Retinal dysplasia can be focal, multifocal, geographic, or accompanied by retinal detachment. Focal and multifocal retinal dysplasia appears as streaks and dots in the central retina. Geographic retinal dysplasia appears as an irregular or horseshoe-shaped area of mixed hyper or hyporeflectivity in the central retina. Retinal detachment occurs with complete retinal dysplasia, and is accompanied by blindness in that eye. Cataracts or glaucoma can also occur secondary to retinal dysplasia. Other causes of retinal dysplasia in dogs include infection with canine adenovirus or canine herpesvirus, or radiation of the eye in newborns.

ENTROPION
Entropion is a medical condition in which the eyelid (usually the lower lid) folds inward. It is very uncomfortable, as the eyelashes constantly rub against the cornea. Entropion is usually caused by genetic factors and may be congenital.[citation needed] Entropion can also occur secondary to pain of the eye (leading to self trauma, scarring of the eyelid, or nerve damage.) The upper or lower eyelid can be involved, and one or both eyes may be affected. When entropion occurs in both eyes, this is known as "bilateral entropion." Trachoma infection may cause scarring of the inner eyelid, which may cause entropion.

DISTICHIA
A distichia is an eyelash that arises from an abnormal spot on the eyelid. The mutation affects dogs. Distichiae usually exit from the duct of the meibomian gland at the eyelid margin. They are usually multiple and sometimes more than one arises from a duct. They can affect either the upper or lower eyelid and are usually bilateral. The lower eyelids of dogs usually have no eyelashes. Distichiae usually cause no symptoms because the lashes are soft, but they can irritate the eye and cause tearing, squinting, inflammation, and corneal ulcers and scarring. Treatment options include manual removal, electrolysis, electrocautery, cryotherapy, and surgery.

CATARACT
A cataract is a clouding that develops in the crystalline lens of the eye or in its envelope (lens capsule), varying in degree from slight to complete opacity and obstructing the passage of light. Early in the development of age-related cataract, the power of the lens may be increased, causing near-sightedness (myopia), and the gradual yellowing and opacification of the lens may reduce the perception of blue colors. Cataracts typically progress slowly to cause vision loss, and are potentially blinding if untreated. The condition usually affects both eyes, but almost always one eye is affected earlier than the other.

PROGRESSIVE RETINAL ATROPHY (PRA)
Progressive retinal atrophy (PRA) is a group of genetic diseases seen in certain breeds of dogs. Similar to retinitis pigmentosa in humans, it is characterized by the bilateral degeneration of the retina, causing progressive vision loss culminating in blindness. The condition in nearly all breeds is inherited as an autosomal recessive trait, with the exception of the Siberian Husky (inherited as an X chromosome linked trait) and the Bullmastiff (inherited as an autosomal dominant trait). There is no treatment.

CHERRY EYE
Cherry eye is the term used to refer to canine nictitans gland prolapse, a common congenital eye defect in various dog breeds where the gland of the third eyelid known as the nictitating membrane prolapses and becomes visible. Commnly affected breeds include the Bulldog, Chihuahua, Cocker Spaniel, Beagle, Pekingese, Neapolitan Mastiff, and Basset Hound. Cherry eye may be caused by a hereditary weakness in the connective tissue surrounding the gland. It is most common in puppies. It appears as a red mass in the inner corner of the eye, and is sometimes mistaken for a tumor. After gland prolapse, the eye becomes chronically inflamed and there is often a discharge. Because the gland is responsible for about 30% of the eye's tear production, the eye can eventually suffer from dryness (keratoconjunctivitis sicca). Dry eye may eventually occur in 30 to 40 percent of dogs that have the gland removed, yet it may affect about 20 percent of dogs that have the gland surgically replaced

DRY EYE/ KERATOCONJUNCTIVITIS (KCS)
Keratoconjunctivitis is inflammation ("-itis") of the cornea and conjunctiva. When only the cornea is inflamed, it is called keratitis; when only the conjunctiva is inflamed, it is called conjunctivitis.

Disorders of the conjunctiva and cornea are a source of eye complaints. The surface of the eye is exposed to various external influences and is especially susceptible to trauma, infections, chemical irritation, allergic reactions and dryness. The conjunctiva can become inflamed secondary to bacterial infection. The resultant condition is known as conjunctivitis and commonly referred to as pinkeye. Conjunctival irritation can occur for a wide variety of reasons including dry eye and overexposure to VOCs (Volatile organic compounds). With age, the conjunctiva can stretch and loosen from the underlying sclera, leading to the formation of conjunctival folds, a condition known as conjunctivochalasis.

CORNEA DYSTROFIE
Corneal endothelial dystrophy is an age-related change that affects the inner layer of the corneal, the endothelium. Leakage of fluid into the cornea causes edema, causing a bluish appearance. This will eventually involve the whole cornea. Bullous keratopathy (blisters in the cornea) may also form, leading to nonhealing and recurrent corneal ulceration. Hyperosmotic agents are sometimes used topically for treatment, but success with these medications is inconsistent and can cause irritation. Bad cases may require a corneal transplant or thermokeratoplasty, which is a grid of superficial burns to the cornea that causes anterior stromal fibers to contract and prevent fluid uptake by the stroma. The most commonly affected breeds are the Boston Terrier, Chihuahua, and Dachshund.