Free ABO Cornea and External Disease Questions and Answers

Question 1

A 25-year-old patient with progressive myopic astigmatism is examined. On downgaze, the lower eyelid is pushed forward into a 'V' shape by the conical cornea. What is this clinical sign called?

Accepted Answer

Munson's sign

Answer

Munson's sign is the V-shaped indentation of the lower eyelid on downgaze, caused by an advanced conical cornea in keratoconus. It is a classic clinical sign indicating significant corneal ectasia.

Question 2

A patient presents with a red, painful eye and foreign body sensation. Slit-lamp examination after fluorescein staining reveals a linear, branching epithelial lesion. This finding is pathognomonic for which condition?

Accepted Answer

Herpes simplex keratitis

Answer

A dendritic ulcer, which appears as a branching, tree-like lesion with terminal bulbs that stain with fluorescein, is the classic presentation of epithelial herpes simplex keratitis. It represents active viral replication within the corneal epithelium.

Question 3

A 60-year-old female complains of blurry vision that is worse in the morning. Slit-lamp examination reveals corneal guttae and stromal edema. The primary pathology in this condition involves which corneal layer?

Accepted Answer

Endothelium

Answer

Fuchs' endothelial dystrophy is characterized by the progressive loss of corneal endothelial cells. This leads to the formation of guttae (excrescences on Descemet's membrane) and a breakdown of the endothelial pump function, resulting in corneal stromal and epithelial edema.

Question 4

A 22-year-old who sleeps in their soft contact lenses presents with severe eye pain, discharge, and a corneal infiltrate with an overlying epithelial defect. Which organism is most notoriously associated with this clinical scenario?

Accepted Answer

Pseudomonas aeruginosa

Answer

Pseudomonas aeruginosa is a gram-negative bacterium commonly associated with contact lens-related infectious keratitis, particularly with overnight wear. It can be highly virulent, causing rapid corneal destruction and perforation if not treated aggressively.

Question 5

A patient with Fuchs' dystrophy and significant corneal edema but a clear stroma is a candidate for a corneal transplant. Which procedure would be most appropriate to selectively replace the diseased tissue?

Accepted Answer

Descemet's Membrane Endothelial Keratoplasty (DMEK)

Answer

Descemet's Membrane Endothelial Keratoplasty (DMEK) is a type of partial-thickness corneal transplant that replaces only the patient's diseased endothelium and Descemet's membrane. It is the preferred procedure for isolated endothelial dysfunction like Fuchs' dystrophy as it offers faster visual recovery and lower rejection rates compared to full-thickness transplants.

ABO - American Board of Ophthalmology Practice Test

ABO - American Board of Ophthalmology Practice Test

Free ABO Cornea and External Disease Questions and Answers