Corneal Lipid

There are 3 main causes of canine corneal lipid deposition.

Corneal lipid keratopathy or corneal lipidosis
Corneal lipid dystrophy
Corneal lipid degeneration

Corneal Lipid Keratopathy/Corneal lipidosis

This occurs when the corneal lipid deposition is secondary to metabolic diseases such as hypothyroidism, pancreatitis, hypercholesterolemia, diabetes, hypercalcemic conditions , Cushings disease, and plasma lipid elevations. Determining the underlying abnormality is essential in controlling this condition as is measuring fasting triglycerides and cholesterol levels. Keratectomy of the lipid plaques is contraindicated until the hyperlidaemic state is resolved as post-operative keratitis may lead to lipid depositing in the surgical site. In addition dietary management can help reduce the amount of lipid deposition.

Corneal lipid Dystrophy

Corneal lipid dystrophies are conditions that are typically non-inflammatory, non-painful and hereditary. They commonly occur bilaterally but at different rates. Depending upon the breed, the age of onset and location of the lipid in the cornea can vary. Whilst they may be slow to progress in some breeds like the Siberian Husky and Cocker Spaniel, they can be more rapid in other breeds such as the Airedale. Unfortunately the mode of inheritance is unknown for most breeds, but it is autosomal recessive in the Siberian Husky.

Corneal lipid Degeneration/ Calcareous Degeneration

Limbal Melanocytoma: These tumours arise from limbal melanocytes and appear as smooth, usually round black swellings at the limbus. They extend into the cornea and back into the sclera for variable distances. Limbal melanocytomas are usually benign but can continue to grow and interfere with function of the eye.

Limbal Melanocytoma Treatment is surgical excision via keratectomy and sclerectomy. It is possible to completely resect the pigmented tissue in some cases. Adjunctive treatment of the base with cryotherapy, diode laser or Strontium 90 is necessary. If the growth is full thickness, the structure of the globe is maintained via autogenous grafting with third eyelid cartilage.