ABO Ocular Pharmacology and Therapeutics 2 — Questions and Answers
Question 1: Which systemic condition is a contraindication to topical timolol?
- Type 2 diabetes mellitus
- Systemic hypertension
- Bronchial asthma (Correct answer)
- Hyperlipidemia
Correct answer: Bronchial asthma
Nonselective beta-blockers like timolol can cause bronchospasm through beta-2 blockade, so they are contraindicated in asthma.
Question 2: Brimonidine is contraindicated in infants and children under 2 years mainly because of which risk?
- Severe allergic follicular conjunctivitis
- CNS depression and apnea (Correct answer)
- Paradoxical IOP elevation
- Corneal endothelial decompensation
Correct answer: CNS depression and apnea
Brimonidine readily crosses the blood-brain barrier in infants, which can cause somnolence, hypotonia, bradycardia, and apnea.
Question 3: Long-term oral acetazolamide therapy is most closely associated with which adverse effect?
- Metabolic alkalosis
- Hyperkalemia
- Calcium phosphate nephrolithiasis (Correct answer)
- Hypoglycemia
Correct answer: Calcium phosphate nephrolithiasis
Carbonic anhydrase inhibition causes metabolic acidosis, reduced urinary citrate, and alkaline urine, which favor calcium phosphate stones.
Question 4: What is the main mechanism by which latanoprost lowers intraocular pressure?
- It reduces aqueous production by the ciliary epithelium
- It contracts the ciliary muscle to open the trabecular meshwork
- It inhibits carbonic anhydrase
- It increases uveoscleral outflow (Correct answer)
Correct answer: It increases uveoscleral outflow
Prostaglandin F2-alpha analogs remodel the ciliary muscle extracellular matrix through matrix metalloproteinases, which increases uveoscleral outflow.
Question 5: Why is pilocarpine often ineffective early in acute angle-closure with IOP above 50 mm Hg?
- Pressure-induced ischemia of the iris sphincter (Correct answer)
- Rapid drug inactivation by aqueous esterases
- Downregulation of muscarinic receptors
- Corneal epithelial edema blocking all drug penetration
Correct answer: Pressure-induced ischemia of the iris sphincter
Very high IOP causes ischemic paralysis of the iris sphincter, so it cannot respond to miotics until pressure is lowered by other means.
Question 6: Which pair of ocular side effects is characteristic of netarsudil?
- Iris darkening and eyelash growth
- Conjunctival hyperemia and corneal verticillata (Correct answer)
- Follicular conjunctivitis and dry mouth
- Bradycardia and bronchospasm
Correct answer: Conjunctival hyperemia and corneal verticillata
The Rho kinase inhibitor netarsudil often causes conjunctival hyperemia and a whorl-like corneal verticillata that is usually benign.
Question 7: Which patient faces the greatest risk from IV mannitol given for acute IOP reduction?
- A patient with a sulfa allergy
- A patient with well-controlled hypothyroidism
- A patient with congestive heart failure (Correct answer)
- A patient taking a topical prostaglandin analog
Correct answer: A patient with congestive heart failure
Mannitol expands intravascular volume and can precipitate pulmonary edema in patients with heart failure or renal failure.
ABO Ocular Pharmacology and Therapeutics 2
Which systemic condition is a contraindication to topical timolol?