Board Certified Ophthalmologist FREE Cornea and External Disease Questions and Answers 2 — Questions and Answers
Question 1: A 45-year-old contact lens wearer presents with a rapidly progressive corneal ulcer and satellite lesions. Culture on Sabouraud agar grows filamentous organisms. Which antifungal agent is the most appropriate first-line treatment?
- Natamycin 5% ophthalmic suspension (Correct answer)
- Fluconazole 0.2% ophthalmic drops
- Amphotericin B 0.15% ophthalmic drops
- Oral itraconazole
Correct answer: Natamycin 5% ophthalmic suspension
Natamycin 5% is the preferred first-line topical antifungal for filamentous fungal keratitis such as Fusarium and Aspergillus species.
Question 2: Which layer of the cornea is most responsible for maintaining corneal deturgescence and transparency?
- Corneal endothelium (Correct answer)
- Bowman layer
- Corneal epithelium
- Descemet membrane
Correct answer: Corneal endothelium
The corneal endothelium actively pumps fluid out of the stroma via Na+/K+-ATPase, maintaining the relative dehydration essential for corneal transparency.
Question 3: A patient with rheumatoid arthritis develops progressive corneal thinning with an overlying epithelial defect in the peripheral cornea. What is the most likely diagnosis?
- Peripheral ulcerative keratitis (Correct answer)
- Mooren ulcer
- Terrien marginal degeneration
- Pellucid marginal degeneration
Correct answer: Peripheral ulcerative keratitis
Peripheral ulcerative keratitis (PUK) is strongly associated with systemic collagen vascular diseases, especially rheumatoid arthritis, and presents with peripheral stromal thinning and an overlying epithelial defect.
Question 4: A 30-year-old male presents with recurrent episodes of unilateral stromal keratitis with decreased corneal sensation. Examination reveals ghost vessels and stromal scarring. Which pathogen is most likely responsible?
- Herpes simplex virus type 1 (Correct answer)
- Varicella-zoster virus
- Acanthamoeba species
- Epstein-Barr virus
Correct answer: Herpes simplex virus type 1
HSV-1 stromal keratitis classically presents with recurrent unilateral inflammation, corneal hypoesthesia, ghost vessels, and progressive stromal scarring.
Question 5: During penetrating keratoplasty, the surgeon notes a positive Seidel test at one of the suture sites on the first postoperative day. The anterior chamber is well-formed. What is the most appropriate initial management?
- Application of a bandage contact lens (Correct answer)
- Immediate return to operating room for resuturing
- Observation without intervention
- Cyanoacrylate tissue adhesive application
Correct answer: Application of a bandage contact lens
A small wound leak with a well-formed anterior chamber can be managed conservatively with a bandage contact lens, which tamponades the leak and promotes epithelial healing over the suture track.
Question 6: Which corneal dystrophy is characterized by bilateral, progressive, asymmetric corneal ectasia with iron deposition in the epithelium forming a Fleischer ring?
- Keratoconus (Correct answer)
- Posterior polymorphous corneal dystrophy
- Fuchs endothelial corneal dystrophy
- Granular corneal dystrophy
Correct answer: Keratoconus
Keratoconus is defined by progressive corneal thinning and ectasia with classic signs including Vogt striae, Fleischer ring (hemosiderin deposits), and Munson sign.
Board Certified Ophthalmologist FREE Cornea and External Disease Questions and Answers 2
A 45-year-old contact lens wearer presents with a rapidly progressive corneal ulcer and satellite lesions.
Culture on Sabouraud agar grows filamentous organisms.
Which antifungal agent is the most appropriate first-line treatment?