GERIATRIC CORNEAL DISEASES
- CORNEAL CALCIUM DEGENERATION
     ■ Calcium is deposited in the anterior to deep stroma of the cornea
     ■ Secondary to systemic disease or age
          • Hypercalcemia, Hyperphosphatemia, Hyperadrenocorticism, Uremia, Hypervitaminosis D
     ■ Complications to Calcium Degeneration
          • Pain when Calcium is exposed because of rough corneal surface
          • Progressive vision impairment
          • Sloughing of calcium
          • Neovascularization into calcific areas
     ■ Treatment for Calcium Degeneration
          • Topical EDTA (1-5%)
          • Trichlorcetic Acid
          • Superficial Keratectomy

- REFRACTORY CORNEAL ULCERS
     ■ Also known as:
          • Indolent ulcers, non-healing ulcers, Boxer ulcers, rodent ulcers, Recurrent corneal erosion syndrome, Spontaneous chronic corneal epithelial defects (SCCED)
     ■ Clinical Signs
          • Loosely adherent epithelium (lipping)
          • Blepharospasms
          • Neovascularization with chronicity
     ■ Underlying Pathophysiology
          • Absence of continuous basement membrane
          • Decrease in hemidesmosomes
          • Extracellular Matrix abnormalities
     ■ Complications of Refractory Ulcers
          • Chronic discomfort, Corneal infection, Corneal neovascularization, fibrosis, and vision loss
     ■ Treatment for Refractory Ulcers
          • Q-tip Debridement
               » 15-25% success rate
          • Linear Grid Keratotomy or Multiple Punctate Keratotomy
               » 95% success rate
          • Others (less than 50% success rate)
               » Contact lens, Third eyelid flap, Chemical cauterization, Topical growth factors

- CORNEAL ENDOTHELIAL DEGENERATION
     ■ Spontaneous, progressive corneal edema
     ■ Abnormal dystrophic endothelial cells
     ■ Prevalent breeds
          • Boston Terrier, Chihuahua, Dachshund, Poodle
     ■ Pathology of Endothelial Degeneration
          • 2500-2800 cell/mm² in the dog
          • Endothelial cells pump fluid from the cornea into the aqueous, keeping the cornea clear and dehydrated.
          • As cells become dystrophic and die, the remaining cells enlarge to compensate.
          • Once there are <500-800 cells/mm² , compensation is lost and fluid is not adequately pumped out of cornea.
     ■ Complications to Endothelial Degeneration
          • Epithelial microbullae formation, Corneal ulcers, Keratoconus, Bullous keratopathy, Vision loss
     ■ Treatment
          • Hyperosmotic Agents (5% sodium chloride ointment)
               » May decrease extent of epithelial bulla formation
               » Does not allow for significant cornea clearing
               » Decreases thickness of cornea
          • Thermokeratoplasty if chronic erosions
          • Penetrating Keratoplasty
               » Improve vision
               » Fresh donor cornea
               » Complication- graft rejection, dehiscence, infection