Board Certified Ophthalmologist Cornea and External Disease Questions and Answers

Question 1

A 24-year-old soft contact lens wearer presents with severe right eye pain that is disproportionate to clinical signs. Slit-lamp examination reveals a stromal ring infiltrate and radial keratoneuritis. What is the most specific diagnostic modality to confirm the suspected diagnosis?

Accepted Answer

In vivo confocal microscopy

Answer

The clinical presentation of severe pain out of proportion to signs, a ring infiltrate, and radial keratoneuritis in a contact lens wearer is highly suggestive of Acanthamoeba keratitis. In vivo confocal microscopy is a rapid, non-invasive imaging technique that allows for the direct visualization of Acanthamoeba cysts and trophozoites within the corneal stroma, providing a highly specific and timely diagnosis. While corneal scraping for culture is a gold standard, it can have low sensitivity and takes a long time. PCR is sensitive but not as specific for direct visualization. Specular microscopy is used to evaluate the endothelium.

Question 2

Which of the following corneal dystrophies is characterized by an autosomal recessive inheritance pattern and the deposition of glycosaminoglycans (mucin) within the corneal stroma?

Accepted Answer

Macular Dystrophy

Answer

Macular Dystrophy is a classic autosomal recessive disorder caused by mutations in the CHST6 gene. This leads to the abnormal synthesis of proteoglycans and the accumulation of glycosaminoglycans (demonstrated by Alcian blue stain) in the stroma, keratocytes, and endothelium, causing diffuse corneal clouding and early vision loss. In contrast, Lattice (amyloid deposits) and Granular (hyaline deposits) dystrophies are typically autosomal dominant. Fuchs' dystrophy primarily affects the endothelium and is usually autosomal dominant or sporadic.

Question 3

A 35-year-old male presents with progressive, painless blurring of vision. Refraction reveals high against-the-rule astigmatism. Corneal topography shows a narrow band of inferior thinning from the 4 o'clock to the 8 o'clock position, located 1-2 mm from the limbus, with steepening of the cornea just superior to this band. The central cornea is of normal thickness. This presentation is most characteristic of which condition?

Accepted Answer

Pellucid Marginal Degeneration

Answer

This description is the classic presentation of Pellucid Marginal Degeneration (PMD). Key features are the peripheral band of inferior thinning (typically 4 to 8 o'clock) located 1-2 mm from the limbus, with the area of maximum protrusion occurring just superior to the thinned area, leading to high against-the-rule astigmatism. This creates a characteristic "crab claw" or "kissing doves" appearance on topography. Keratoconus typically involves central or paracentral thinning and protrusion, while keratoglobus involves global corneal thinning.

Question 4

A 30-year-old patient is diagnosed with active herpes simplex virus (HSV) epithelial keratitis, characterized by a well-defined dendritic ulcer with terminal bulbs that stains with fluorescein. Which of the following interventions is strictly contraindicated in the management of this patient?

Accepted Answer

Topical prednisolone acetate

Answer

The use of topical corticosteroids, such as prednisolone acetate, is absolutely contraindicated in active HSV epithelial keratitis. Steroids suppress the local immune response, which can lead to increased viral replication, enlargement of the epithelial defect into a "geographic ulcer," and a heightened risk of stromal melting and perforation. Management should focus on antiviral therapy, either topical (ganciclovir) or oral (valacyclovir), with debridement being an occasional adjunct.

Question 5

A 72-year-old patient is seen on postoperative day 1 after Descemet's Membrane Endothelial Keratoplasty (DMEK). The cornea is edematous, and a large, partially detached but correctly oriented graft is noted in the anterior chamber. What is the most appropriate next step in management?

Accepted Answer

Perform a rebubbling procedure with air or gas

Answer

A large, clinically significant graft detachment is the most common complication after DMEK and requires intervention. The standard of care is to perform a "rebubbling" procedure, which involves injecting an air or gas bubble into the anterior chamber to push the graft back into apposition with the host stroma. This is often successful and avoids the need for a more invasive procedure. Proceeding to PKP is overly aggressive. Observation or medical management alone is insufficient for a large mechanical detachment.

Board Certified Ophthalmologist Practice Test

Board Certified Ophthalmologist Practice Test

Board Certified Ophthalmologist Cornea and External Disease Questions and Answers