Lecture 4/5 2/4/25 and 2/6/25 Flashcards
(36 cards)
What is pigmentary keratitis?
corneal changes that occur with chronic trauma/irritation that manifests as corneal pigmentation, vascularization, and scarring
What are the etiologies of pigmentary keratitis?
-keratoconjunctivitis sicca
-trichiasis/aberrant dermis
-nasal fold trichiasis
-pagoda lid/ectropion
-lagophthalmia
-entropion
-pannus
What is pannus?
immune-mediated, vascularized, pigmented lesion of the cornea
What are the etiologic factors of pannus?
-immune-mediated disease
-genetic factors
-UV radiation
Which breed is predisposed to pannus?
german shepherds
How is pannus diagnosed?
-appearance
-signalment
-lymphocytes and plasma cells on cytology
How is pannus treated?
-topical dexamethasone or prednisone
-cyclosporine or tacrolimus (maintenance)
-strontium radiation in severe cases
What are the possible differentials for white-looking corneal lesions?
-scars
-corneal/lipid dystrophy
-corneal/lipid/calcific degeneration
-corneal edema
-corneal stria
What do corneal scars result from?
-abnormal alignment of corneal stromal lamella
-secondary to ulceration or chronic disease
How are corneal scars diagnosed?
-grey irregular opacity appearance +/- vessels and pigment
-fluorescein negative
What is corneal/lipid dystrophy?
-primary, bilateral, inherited disorder of the cornea
-not accompanied by corneal inflammation of systemic disease
What is the etiology of corneal/lipid dystrophy?
-inherited condition of abnormal corneal metabolism
-most common in shetland sheepdogs, beagles, huskies
What is the appearance of corneal dystrophy?
-bilateral and symmetrical
-oval white/grey glittery refractile opacity
-no vessels
What is the treatment for corneal dystrophy?
-typically not indicated
-low fat diet may help
-potential for response to cyclosporine
-may improve with treatment for Cushing’s or hypothyroidism if disease is concurrent
What is corneal/lipid degeneration?
-deposition of lipid and/or calcium secondary to some other ocular disease
-can occur secondary to chronic topical steroid use
What is the appearance of lipid degeneration?
-white grey glittery appearance
-possible to have vessels and pigmentation
What is the treatment for lipid degeneration?
-typically not indicated
-low fat diet may help
-potential for response to cyclosporine
-may improve with treatment for Cushing’s or hypothyroidism if disease is concurrent
What are the characteristics of calcific keratopathy?
-deposition of mineral (calcium) in the cornea
-appears as short spicules of white, chalky looking material
-may be primary disease in geriatric dogs
What is the treatment for calcific keratopathy?
severe disease can be treated with topical EDTA in artificial tears; chelates calcium
What are the causes of corneal edema?
-glaucoma
-ulceration
-anterior uveitis
-endothelial dystrophy
-lens luxation
Which mechanisms typically prevent corneal edema?
-endothelial Na-K ATPase pumps
-corneal epithelium acting as a physical barrier; keeps tears out of stroma
What are the characteristics of endothelial dystrophy?
-progressive dysfunction of endothelial cells
-seen in middle to older age dogs
-results in axial or temporal focus of corneal edema; eventual progression to involve entire cornea
-can lead to formation of bullae/blisters within cornea
What are the characteristics of endothelial degeneration?
-can occur with anything that traumatizes, touches, or negatively affects corneal endothelium
-aging can be a cause due to loss of complement of endothelial cells
-endothelial cells cannot replace themselves because they are post-mitotic; cell loss can lead to edema in old age
What is the treatment for corneal edema?
NaCl ophthalmic ointment that reduces edema and prevents formation of bullae
