On slit-lamp examination, a follicle differs from a papilla in that a follicle:
- A Has a central fibrovascular core with vessels reaching its apex
- B Is a lymphoid aggregation whose centre is avascular, with vessels passing around its periphery ✓
- C Occurs only on the bulbar conjunctiva
- D Represents hypertrophy of the epithelial layer alone
Correct answer: B. Is a lymphoid aggregation whose centre is avascular, with vessels passing around its periphery
Explanation
A follicle is a subepithelial lymphoid aggregation with germinal centres; its centre is avascular and the conjunctival vessels course around its periphery, giving a pale centre with a vascular rim. A papilla, by contrast, is formed by hyperplastic epithelium thrown into folds around a central fibrovascular core with a vessel reaching its apex, which is exactly what option A describes. Follicles dominate in viral and chlamydial infections, papillae in allergic and bacterial disease.
Reference: Parsons' Diseases of the Eye, 23rd ed.
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Written and medically reviewed by the StethoPrep medical team.