Cornea and Sclera Part I Flashcards
what is the corneal epithelium?
stratified nonkeratinized squamous epithelium
what makes up 90% of the corneal thickness?
corneal stroma
what is corneal dystrophy?
axial lipid deposition
what is pigmentary keratitis?
pigment from limbal stem cells
what makes up the fibrous tunic of the eye?
cornea
sclera
limbus
what is thee limbus?
junction between cornea, sclera, conjunctiva
what innervates the cornea?
ophthalmic branch of trigeminal nerve: CN V
concentrated in epithelium and just below
is corneal epithelium hydrophobic or hydrophilic?
hydrophobic
how thick is the corneal epithelium in a dog or cat?
25-40 micrometers
what are the layers of the corneal epithelium?
single layer of basal cells
2-3 layers of intermediate cells
2-3 layers of superficial cells
what is the life cycle of basal cells?
transform, migrate, sloughed in 7-10 days
what are the three components of thee corneal stroma?
cells: mostly keratocytes
ground substance
collagen fibrils
what does ground substance do?
regulate hydration
maintain collagen spacing
what are collagen fibrils arranged for in corneal stroma?
to limit light scatter
how thick is descemet’s membrane?
10-15 micrometers
thickens with age
what are the junctions between cells in corneal endothelium?
macula occludens
what regulates corneal hydration?
active maintenance of osmotic gradient between corneal stroma and aqueous
can corneal endothelium divide and replicate?
no
is fluoroscein staining hydrophobic or hydrophilic?
hydrophilic and lipophobic
what filter should you use for fluoroscein staining?
cobalt blue filter
what will fluoroscein staining not stain?
descemet’s membrane
epithelium
edematous tissue
melting tissue
what does rose bengal staining stain?
areas with insufficient tear film
what is a dermoid?
congenital
normal tissue growing in abnormal area
what does edema look like?
white lesion
mottled appearance
diffuse/indistinct borders
when does corneal dystrophy show up?
early in life
who commonly gets endothelial degeneration/decompensation?
older small-breed dogs
pit bulls
what is pigmentary keratitis a response to?
chronic irritation
what is pannus?
chronic superficial keratitis
bilateral
does pannus usually respond well to treatment?
yes
what is pathognomonic of feline herpetic keratitis?
dendritic corneal lesions
what does feline eosinophilic keratoconjunctivitis look like?
fleshy infiltrates
white caseous plaques
how are feline corneal sequestrums treated?
keratectomy +/- graft
medical management usually unrewarding
