AOA Ocular Pharmacology 2 — Questions and Answers
Question 1: Which class of drugs is specifically contraindicated with topical pilocarpine due to risk of cholinergic toxicity?
- Systemic cholinesterase inhibitors (e.g., echothiophate iodide) (Correct answer)
- Topical beta-blockers
- Systemic carbonic anhydrase inhibitors
- Topical prostaglandin analogs
Correct answer: Systemic cholinesterase inhibitors (e.g., echothiophate iodide)
Echothiophate (an irreversible cholinesterase inhibitor) combined with pilocarpine produces additive muscarinic stimulation; echothiophate also prolongs succinylcholine-induced apnea in surgery.
Question 2: Brimonidine (alpha-2 agonist) lowers IOP through which dual mechanism?
- Decreasing aqueous production AND increasing uveoscleral outflow (Correct answer)
- Increasing trabecular outflow only
- Decreasing uveoscleral outflow only
- Blocking muscarinic receptors in ciliary body
Correct answer: Decreasing aqueous production AND increasing uveoscleral outflow
Brimonidine stimulates alpha-2 adrenergic receptors to both decrease aqueous production (reduced cAMP) and increase uveoscleral outflow, achieving a 20–25% IOP reduction.
Question 3: Topical corticosteroids used for ocular inflammation can cause which serious ocular complication with prolonged use?
- Posterior subcapsular cataracts and elevated IOP (steroid-induced glaucoma) (Correct answer)
- Corneal neovascularization and thinning
- Retinal detachment and macular hole
- Optic nerve drusen and pseudopapilledema
Correct answer: Posterior subcapsular cataracts and elevated IOP (steroid-induced glaucoma)
Long-term topical steroid use induces posterior subcapsular cataracts and increases IOP in susceptible 'steroid responders' by reducing trabecular outflow facility.
Question 4: Which mydriatic agent is preferred for fundus examination in pediatric patients due to its shorter duration?
- Tropicamide 0.5–1% (Correct answer)
- Atropine 1%
- Scopolamine 0.25%
- Phenylephrine 10%
Correct answer: Tropicamide 0.5–1%
Tropicamide has a short duration (4–8 hours) making it practical for routine dilation, while atropine's 7–14 day effect is reserved for cycloplegic refraction when needed.
Question 5: Systemic side effects of topical phenylephrine 10% include:
- Hypertension and tachycardia due to systemic absorption (Correct answer)
- Bradycardia and bronchospasm
- Hypoglycemia and sedation
- Urinary retention and constipation
Correct answer: Hypertension and tachycardia due to systemic absorption
Phenylephrine 10% can be absorbed systemically via nasolacrimal drainage, stimulating alpha-1 receptors to cause hypertension, sometimes severe, especially in elderly patients.
Question 6: Topical antihistamine-mast cell stabilizer combinations (e.g., olopatadine) are first-line treatment for:
- Allergic conjunctivitis (Correct answer)
- Bacterial conjunctivitis
- Viral keratoconjunctivitis
- Fungal keratitis
Correct answer: Allergic conjunctivitis
Dual-acting antihistamine/mast cell stabilizers like olopatadine block H1 receptors and prevent mast cell degranulation, providing rapid and sustained relief from allergic conjunctivitis symptoms.
AOA Ocular Pharmacology 2
Which class of drugs is specifically contraindicated with topical pilocarpine due to risk of cholinergic toxicity?