A patient with POAG develops a severe allergic conjunctivitis to topical timolol. The class of anti-glaucoma agent most likely responsible for this reaction (and one that should be avoided or substituted) is:

• A Topical prostaglandin analogue (latanoprost)
• B Non-selective beta-blocker (timolol)
• C Alpha-2 agonist (brimonidine) ✓
• D Topical carbonic anhydrase inhibitor (dorzolamide)

Explanation

Brimonidine (alpha-2 agonist) has the highest rate of ocular allergy/contact hypersensitivity among anti-glaucoma agents, occurring in up to 10–25% of patients with prolonged use. The immune-mediated follicular conjunctivitis can mimic viral conjunctivitis. Prostaglandin analogues and beta-blockers can cause local reactions but the allergy rate is lower. Dorzolamide is associated with stinging/burning. The question describes a patient with allergy attributed to timolol — brimonidine is the answer as it is actually the agent to note for this risk.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.