ABO Cornea and External Disease 2 — Questions and Answers
Question 1: A soft contact lens wearer who rinses lenses with tap water has severe pain out of proportion to exam findings and radial perineuritis. What is the most likely organism?
- Pseudomonas aeruginosa
- Acanthamoeba species (Correct answer)
- Fusarium solani
- Herpes simplex virus
Correct answer: Acanthamoeba species
Radial perineuritis with pain out of proportion in a contact lens wearer exposed to water is classic for early Acanthamoeba keratitis.
Question 2: Which genetic abnormality is most commonly associated with late-onset Fuchs endothelial corneal dystrophy?
- TGFBI R124H mutation
- CHST6 mutation
- CTG trinucleotide repeat expansion in TCF4 (Correct answer)
- ZEB1 mutation
Correct answer: CTG trinucleotide repeat expansion in TCF4
A CTG repeat expansion in an intron of TCF4 is found in most patients with late-onset Fuchs dystrophy.
Question 3: Corneal stromal deposits in granular corneal dystrophy type 1 stain most characteristically with which stain?
- Masson trichrome (Correct answer)
- Congo red
- Alcian blue
- Colloidal iron
Correct answer: Masson trichrome
Granular dystrophy deposits are hyaline and stain bright red with Masson trichrome.
Question 4: Which corneal stromal dystrophy is inherited in an autosomal recessive pattern and is caused by CHST6 mutations?
- Lattice corneal dystrophy type 1
- Granular corneal dystrophy type 2
- Schnyder corneal dystrophy
- Macular corneal dystrophy (Correct answer)
Correct answer: Macular corneal dystrophy
Macular corneal dystrophy is autosomal recessive and results from abnormal keratan sulfate production caused by CHST6 mutations.
Question 5: An elderly patient has a painful peripheral corneal ulcer with an overhanging central edge and no scleritis or systemic disease after a full workup. What is the most likely diagnosis?
- Terrien marginal degeneration
- Mooren ulcer (Correct answer)
- Staphylococcal marginal keratitis
- Rheumatoid peripheral ulcerative keratitis
Correct answer: Mooren ulcer
Mooren ulcer is an idiopathic, painful peripheral ulcer with an undermined leading edge and no associated scleritis or systemic disease.
Question 6: Which topical agent is FDA-approved for moderate-to-severe (stage 2 and 3) neurotrophic keratitis?
- Cyclosporine 0.05%
- Lifitegrast 5%
- Cenegermin (recombinant human nerve growth factor) (Correct answer)
- Autologous serum 20%
Correct answer: Cenegermin (recombinant human nerve growth factor)
Cenegermin, a recombinant human nerve growth factor, is FDA-approved for neurotrophic keratitis.
Question 7: What is the preferred chelating agent for removing visually significant calcific band keratopathy?
- Disodium EDTA (Correct answer)
- Penicillamine
- Deferoxamine
- Dimercaprol
Correct answer: Disodium EDTA
After epithelial debridement, topical disodium EDTA chelates the calcium deposited in Bowman layer.
ABO Cornea and External Disease 2
A soft contact lens wearer who rinses lenses with tap water has severe pain out of proportion to exam findings and radial perineuritis.
What is the most likely organism?