A 72-year-old man with Fuchs endothelial corneal dystrophy and early corneal guttae is started on topical dorzolamide for mild glaucoma. Over several weeks he develops increasing corneal oedema and blurred vision. The most likely mechanism is:

• A Drug-induced activation of latent herpes simplex keratitis
• B Benzalkonium chloride induced destruction of corneal stem cells at the limbus
• C Impairment of corneal endothelial pump function due to carbonic anhydrase inhibition in the endothelium ✓
• D Osmotic dehydration of the stroma causing folds in Descemet membrane

Explanation

Corneal endothelium uses carbonic anhydrase in its fluid transport pump to maintain deturgescence. Topical carbonic anhydrase inhibitors can compromise this pump, so dorzolamide is avoided or used cautiously in patients with compromised endothelium such as Fuchs dystrophy or corneal grafts. Herpes reactivation is a described but unrelated adverse event, and preservative toxicity does not selectively produce endothelial decompensation in this pattern.

Reference: American Academy of Ophthalmology Basic and Clinical Science Course, Glaucoma Section, 2023 ed.

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Written and medically reviewed by the StethoPrep medical team.