MCPHS ANTERIOR SEG: CORNEA EXAM QUESTIONS
AND ANSWERS WITH COMPLETE SOLUTIONS
VERIFIED
Corneal Innervation
Derived from ciliary nerves that penetrate cornea in deep peripheral stroma, lose myelination shortly
after entering cornea. Terminate in wing cells of epi
Cornea: Epithelium
surface layer, 55um, barrier function (block debris, bacteria, foreign), constantly regenerated + sloughed
Cornea: Bowman's Layer
Basement membrane, 5um, prevents forward corneal swelling
Cornea: Stroma
Majority of the cornea, 485um, strength + elasticity
Cornea: Dua's Layer
Newly discovered, 10-15um, Unknown fxn
Cornea: Descemet's Layer
Basement membrane, 10um, Endothelial cell health
, Cornea: Endothelium
Innermost layer, 5um (1 cell thick), barrier pump maintaining appropriate corneal hydration
Arcus Senilis
Degenerative change involving deposition of lipid in peripheral cornea. Gray/white arc progresses into a
ring w/ sharp peripheral border and diffsue central border. Limbal intervening zone.
Fish-Eye Disease
LCAT deficiency -- progressive arcus which begins in adolescence. May result in complete opacification.
Usually asymptomatic besides cosmesis.
Lipid Degeneration
Dense yellow-white opacity that may fan out with feathery edges. Deposits consist of cholesterol, fats,
phospholipids. Two types (primary + secondary)
Spheroidal Degeneration
Clear to yellow-gold spherules seen in subepithelium, within Bowmans, or in superficial corneal stroma.
They may darken with age. Three types (primary corneal involvement, corneal involvement 2^ to
underlying, conj involvement)
Amyloid Degneration
Groups of proteins with starch-like characteristics. Stains with Congo Red, birefingence in polarized light,
and dichromism in green light. Primary of secondary forms
Salzmann's Nodular Degeneration
AND ANSWERS WITH COMPLETE SOLUTIONS
VERIFIED
Corneal Innervation
Derived from ciliary nerves that penetrate cornea in deep peripheral stroma, lose myelination shortly
after entering cornea. Terminate in wing cells of epi
Cornea: Epithelium
surface layer, 55um, barrier function (block debris, bacteria, foreign), constantly regenerated + sloughed
Cornea: Bowman's Layer
Basement membrane, 5um, prevents forward corneal swelling
Cornea: Stroma
Majority of the cornea, 485um, strength + elasticity
Cornea: Dua's Layer
Newly discovered, 10-15um, Unknown fxn
Cornea: Descemet's Layer
Basement membrane, 10um, Endothelial cell health
, Cornea: Endothelium
Innermost layer, 5um (1 cell thick), barrier pump maintaining appropriate corneal hydration
Arcus Senilis
Degenerative change involving deposition of lipid in peripheral cornea. Gray/white arc progresses into a
ring w/ sharp peripheral border and diffsue central border. Limbal intervening zone.
Fish-Eye Disease
LCAT deficiency -- progressive arcus which begins in adolescence. May result in complete opacification.
Usually asymptomatic besides cosmesis.
Lipid Degeneration
Dense yellow-white opacity that may fan out with feathery edges. Deposits consist of cholesterol, fats,
phospholipids. Two types (primary + secondary)
Spheroidal Degeneration
Clear to yellow-gold spherules seen in subepithelium, within Bowmans, or in superficial corneal stroma.
They may darken with age. Three types (primary corneal involvement, corneal involvement 2^ to
underlying, conj involvement)
Amyloid Degneration
Groups of proteins with starch-like characteristics. Stains with Congo Red, birefingence in polarized light,
and dichromism in green light. Primary of secondary forms
Salzmann's Nodular Degeneration
