Cornea and External Disease Flashcards
7 cards from real ABO practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Cornea and External Disease flashcards as text
In standard epithelium-off (Dresden protocol) corneal collagen crosslinking for keratoconus, what is the irradiation source?
Answer: Ultraviolet A at about 365-370 nm, 3 mW/cm2 for 30 minutes
The Dresden protocol uses riboflavin drops with UVA at about 370 nm and 3 mW/cm2 for 30 minutes (5.4 J/cm2).
A patient with keratoconus has sudden corneal edema and decreased vision. What is the underlying cause of acute hydrops?
Answer: A break in Descemet membrane
Acute hydrops occurs when Descemet membrane ruptures, which lets aqueous enter the stroma; it is usually managed conservatively.
A line of keratic precipitates moving across the donor endothelium after penetrating keratoplasty, with stromal edema behind it, indicates what?
Answer: Endothelial graft rejection (Khodadoust line)
A Khodadoust line is the hallmark of endothelial rejection and calls for intensive topical corticosteroids.
Compared with DSAEK, which statement about DMEK is most accurate?
Answer: DMEK has a lower rejection rate but a higher rebubbling rate
DMEK gives faster, better visual recovery and less rejection, but graft detachment needing rebubbling is more common.
Inferior peripheral corneal thinning 1-2 mm from the limbus, with the protrusion above the thinned band and a 'crab claw' topography, suggests which diagnosis?
Answer: Pellucid marginal degeneration
Pellucid marginal degeneration causes inferior band thinning with ectasia above it and a 'kissing doves' or crab-claw topography pattern.
A middle-aged woman has unilateral corneal edema, corectopia, and a 'hammered silver' endothelium. What is the most likely diagnosis?
Answer: Iridocorneal endothelial syndrome
ICE syndrome is typically unilateral and occurs in middle-aged women, with abnormal endothelium, iris changes, and secondary glaucoma.
Which donor history is an absolute contraindication to using corneal tissue for transplantation?
Answer: Creutzfeldt-Jakob disease
Prion diseases such as Creutzfeldt-Jakob disease have been transmitted by corneal grafts and are an absolute exclusion.