Board Certified Ophthalmologist FREE Board Certified Ophthalmologist Cornea and External Disease Questions and Answers 2 — Questions and Answers
Question 1: A 45-year-old contact lens wearer presents with a ring-shaped corneal infiltrate and severe pain. Culture reveals Acanthamoeba. What is the most appropriate initial treatment?
- Polyhexamethylene biguanide (PHMB) with propamidine (Correct answer)
- Topical fluoroquinolone monotherapy
- Oral acyclovir
- Topical natamycin alone
Correct answer: Polyhexamethylene biguanide (PHMB) with propamidine
Acanthamoeba keratitis is treated with dual therapy using a biguanide (PHMB or chlorhexidine) combined with a diamidine (propamidine) to target both trophozoites and cysts.
Question 2: Which layer of the cornea is most affected in Fuchs endothelial corneal dystrophy?
- Descemet membrane and endothelium (Correct answer)
- Bowman layer
- Epithelial basement membrane
- Stroma
Correct answer: Descemet membrane and endothelium
Fuchs dystrophy is characterized by progressive loss of endothelial cells and thickening of Descemet membrane with guttae formation.
Question 3: A patient with recurrent corneal erosion syndrome has failed conservative management with lubricants and bandage contact lenses. What is the next appropriate intervention?
- Anterior stromal micropuncture or epithelial debridement with diamond burr polishing (Correct answer)
- Penetrating keratoplasty
- Amniotic membrane transplantation
- Topical cyclosporine alone
Correct answer: Anterior stromal micropuncture or epithelial debridement with diamond burr polishing
Anterior stromal micropuncture or diamond burr polishing promotes stronger epithelial adhesion by disrupting the abnormal basement membrane.
Question 4: What is the hallmark finding on slit-lamp examination in lattice corneal dystrophy type I?
- Refractile branching lines in the anterior stroma (Correct answer)
- Central geographic iron deposits
- Dense white granular deposits in Bowman layer
- Diffuse posterior stromal haze
Correct answer: Refractile branching lines in the anterior stroma
Lattice dystrophy type I (TGFBI mutation) is characterized by refractile branching amyloid deposits in the anterior and mid-stroma.
Question 5: A 60-year-old presents with a chronic, non-healing corneal ulcer with a gray-white feathery border and satellite lesions. What is the most likely causative organism?
- Fusarium or Aspergillus species (Correct answer)
- Staphylococcus aureus
- Pseudomonas aeruginosa
- Herpes simplex virus
Correct answer: Fusarium or Aspergillus species
Feathery borders with satellite lesions are classic features of fungal keratitis, most commonly caused by filamentous fungi such as Fusarium or Aspergillus.
Question 6: Which surgical procedure selectively replaces the posterior corneal layers while preserving the patient's anterior stroma?
- Descemet membrane endothelial keratoplasty (DMEK) (Correct answer)
- Penetrating keratoplasty (PKP)
- Deep anterior lamellar keratoplasty (DALK)
- Phototherapeutic keratectomy (PTK)
Correct answer: Descemet membrane endothelial keratoplasty (DMEK)
DMEK transplants only the donor Descemet membrane and endothelium, providing faster visual recovery and lower rejection rates than full-thickness grafts.
Board Certified Ophthalmologist FREE Board Certified Ophthalmologist Cornea and External Disease Questions and Answers 2
A 45-year-old contact lens wearer presents with a ring-shaped corneal infiltrate and severe pain.
Culture reveals Acanthamoeba.
What is the most appropriate initial treatment?