Facts About Corneal Endothelial Degeneration

 

What is corneal endothelial degeneration?

          Corneal endothelial degeneration is a disease that affects the outer clear window of the eye, or the cornea. The inner surface of the cornea is lined by a single layer of cells called endothelial cells. The main function of these cells is to pump water (or aqueous humor) that leaks into the cornea back into the front chamber of the eye (the anterior chamber). If the endothelial cells lose their pump like ability, then the cornea becomes cloudy due to water accumulation. This is referred to as corneal edema, and edema is the main sign of corneal endothelial degeneration.

          Endothelial degeneration typically occurs in middle-aged or older dogs and can affect one or both eyes. The exact cause for endothelial cell dysfunction is unknown. It can occur in any dog breed, but there is a predilection for the Boston Terrier and the Chihuahua to be affected. In these latter breeds where there is presumably a genetic (or inherited) basis for the disease, it is also called corneal endothelial dystrophy. The human counterpart to this disease is called Fuch's dystrophy. A similar condition occurs in the Manx cat.

 

What are the symptoms of Corneal Endothelial Degeneration?

          The first symptoms of corneal endothelial degeneration are slight cloudiness, or edema, of the eyes usually at the outside corner of the eyes. Over a period of many weeks, months, or sometimes years, the edema usually progresses to affect the entire cornea. Progressive edema is associated with decreased vision and redness (or conjunctivitis) of the eyes. In advanced cases, fluid pockets, called bullae (pronounced bully) form on the surface of the cornea. These bullae can rupture to the surface resulting in defects, or ulcers, in the cornea. Corneal ulcers result in discomfort to the dog and mark the point where the disease changes from a non-painful to a potentially painful disorder.

 

What is the treatment for Corneal Endothelial Degeneration?

          Corneal endothelial degeneration is one of the most frustrating eye diseases of dogs that we routinely encounter at the eye clinic because treatment options are limited. Medical treatment is started using a salt preparation with the intent of reducing the fluid accumulation in the cornea. Salt preparations (or sodium chloride) intended for use on the eye can be purchased over-the-counter at any drug store and can be obtained as a 5% suspension or ointment. AS common brand name is Muro-128. The ointment may be more effective. A topical cortisone treatment may also be used to reduce irritation of the eyes.

          Surgery may be indicated in certain patients. In people, this condition is treated by corneal transplant surgery (penetrating keratoplasty), but this is a rarely performed procedure in animals, Corneal transplant can be considered, but donor corneal tissue is not readily available, the surgery is relatively expensive, and the results are variable. In dogs that are experiencing corneal ulceration and recurrent pain, a less invasive procedure called thermokeratoplasty may be performed. In this latter procedure, multiple burns are made on the surface of the eye with the intent of producing moderate scar tissue. The scar tissue reduces the tendency for recurrent corneal ulceration, but in most instances, the cornea will continue to be cloudy.

 

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