Fuchs' endothelial corneal dystrophy affects primarily the corneal endothelium. The MECHANISM of corneal oedema in this condition is:

• A Increased aqueous humour production overwhelming the endothelial pump
• B Increased stromal keratan sulphate concentration causing osmotic swelling
• C Dysfunction of the tight junctions between epithelial cells
• D Loss of endothelial cells causing failure of the active Na-K ATPase pump, allowing aqueous to passively enter the stroma ✓

Explanation

Fuchs' dystrophy results from progressive loss of corneal endothelial cells due to deposition of collagen in Descemet's membrane (guttae). The endothelium normally maintains corneal dehydration via an active metabolic pump (Na-K ATPase and carbonic anhydrase). When endothelial cell density falls below ~500 cells/mm², the pump fails to compensate for osmotic water entry, leading to stromal and eventually epithelial (bullous keratopathy) oedema. Stromal GAG composition is secondary. Epithelial tight junctions are intact.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.