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    Corneal Dystrophy

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    What Is Corneal Dystrophy?

    Dystrophy is any disorder due to defective or faulty nutrition. Corneal dystrophy is an inherited eye disease characterized by the development of gray-white or silver crystalline opacities in or around the central area of the cornea. The preferred veterinary term for this condition is Crystalline Corneal Opacities (CCOs). The opacities are produced by cone-shaped crystals that form in the cornea and spread across the surface of the eye, potentially interfering with the dog’s vision. The symmetrical opacities are almost always present in the same area of both eyes with no accompanying inflammation or systemic illness.

    Dystrophies differ from corneal degenerations because they usually affect both eyes as in bilateral cataracts (though not simultaneously or to the same degree in every incidence), appear in certain breeds, do not have inflammation, often affect connective and supportive tissue constituting the thickest layer of the cornea (stroma) and rarely cause blindness.

    Classifications, Causes & Treatment

    Epithelial & basement membrane

    Usually present as non-healing ulcers and can be initiated by slight trauma to the epithelial surface of the eye.

    Stromal deposits of lipids

    Commonly seen as an inherited condition in several breeds; these deposits often cause swelling of the cornea. Stromal dystrophies seldom lead to loss of vision, except in middle-aged Airedale Terriers and aged Siberian Huskies. Treatment is usually unnecessary.

    Endothelial dystrophy

    It is usually associated with progressive corneal edema (abnormal fluid accumulation in tissues or body cavities that appears as swelling), which can lead to corneal ulcers. Unless the edema becomes severe enough to cause ulceration, the disease is non-painful.

    Treatment with hyperosmotic 5% sodium chloride ointment applied 4 times a day daily may reduce edema. A surgical procedure called “thermokeratoplasty” may be beneficial in advanced cases. It involves the creation of multiple superficial corneal burns to create superficial corneal fibrosis that leads to the formation of a scar.2

    If the dystrophy affects the deepest layer of the cornea, as it does in Boston Terriers, Chihuahuas and Dachshunds, it can lead to blindness. Most dystrophies are more superficial, such as those seen in Siberian Huskies, Beagles and King Charles Spaniels. Affected dogs should not be bread to avoid perpetuating the effect.

    Video Credits: VetVid
    Image Credits: Joe Mills, Wikipedia

    References

    1. Cooley et al. – Corneal Dystrophy In The Dog And Cat
    2. David J. Maggs, Paul E. Miller, Ron Ofri, Douglas H. Slatter. – Slatter’s Fundamentals of Veterinary Ophthalmology
    3. Heidi Featherstone, Elaine Hol – Small Animal Ophthalmology: What’s Your Diagnosis

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