Corneal Dystrophy
Corneal dystrophy and corneal degeneration are diseases of the cornea characterized by white, opaque mineral (either cholesterol or calcium) deposits within the cornea (the clear front part of the eye). The size, shape, and density of the areas of mineral deposits vary. Although these affected areas can be highly visible, they rarely cause blindness.
Corneal dystrophy may be an inherited trait in several breeds, including the Shetland Sheepdog, Siberian Husky, Beagle, American Cocker Spaniel, Miniature Schnauzer, and Airedale Terrier. Corneal dystrophy affects both eyes and occurs in dogs of any age. It has been reported to occur in dogs with high levels of cholesterol or calcium in their blood. Routine blood work can be performed to evaluate for these possible changes.
Corneal degeneration can affect one or both eyes, and may occur in areas of the cornea that have suffered a traumatic incident or chronic disease process. It is not an uncommon finding at the center of the cornea in our geriatric patients.
Corneal dystrophy and corneal degeneration can lead to corneal ulcers (superficial to deep), ocular infections, and corneal scarring and vascularization arising from continuous sloughing of the mineral deposits. Severe cases can cause visual impairment.
Treatment
Our goal in treating corneal dystrophy and corneal degeneration with topical medication is to improve the health of normal cells overlying the corneal minerals. We may also treat these diseases through dietary management (low-fat, high-fiber diets).
Some patients may be candidates for treatment with a topical acid treatment (TCA), which helps to dissolve the mineral. This treatment may be performed once or multiple times and is often effective in improving comfort, reducing the mineral and preventing further ulcers.
In cases of severe progression and discomfort, we can remove the mineral deposits through superficial keratectomy, a surgery in which the outer layer of the cornea and the mineral is removed; however, scar tissue may remain present instead of the mineral deposits. If a deep ulcer is found as a result of the degeneration, a grafting procedure may be necessary to allow the cornea to heal. Although most corneal dystrophy patients do not require surgical intervention, some pets will, and their owners should be aware of potential complications. Any surgical procedure can introduce complications, including potential anesthetic risks. Surgical procedures that involve the cornea seldom give rise to complications, which occur in less than five percent of these cases. Nevertheless, potential complications include, but are not limited to…
- Inflammation of the pink tissue (conjunctivitis)
- Breakdown of the tissue or suture (wound dehiscence/graft retraction/rejection)
- Infections at the surgical site, which may extend to other internal and/or external areas of the eye (intraocular/extraocular infections)
- Corneal ulcerations (superficial to deep)
- Corneal scarring, vascularization, or mineralization
- Rupture of the eye, secondary to ulceration
- Inflammation inside the eye (uveitis)
- High pressure within the eye (glaucoma), secondary to uveitis
- Retinal detachment or degeneration, secondary to uveitis or infection
- Ocular or orbital pain, secondary to uveitis, glaucoma or infection
- Eyelid rubbing
- Bleeding inside the eye (hyphema)
- Excessive tearing
- Lens luxation, secondary to uveitis, glaucoma or infection
Some of these complications can lead to blindness.
