AOA Ocular Pharmacology 1 — Questions and Answers
Question 1: Prostaglandin analogs (e.g., latanoprost) lower intraocular pressure by:
- Increasing aqueous outflow through the uveoscleral pathway (Correct answer)
- Decreasing aqueous production by the ciliary body
- Increasing conventional trabecular outflow only
- Constricting the pupil to open the drainage angle
Correct answer: Increasing aqueous outflow through the uveoscleral pathway
Prostaglandin analogs primarily enhance uveoscleral (non-conventional) aqueous outflow by remodeling the ciliary body extracellular matrix, reducing IOP by 25–35%.
Question 2: Topical beta-blockers such as timolol lower IOP by:
- Decreasing aqueous humor production by the ciliary body (Correct answer)
- Increasing uveoscleral outflow
- Constricting pupil diameter to widen the drainage angle
- Decreasing episcleral venous pressure
Correct answer: Decreasing aqueous humor production by the ciliary body
Beta-blockers block beta-2 adrenoceptors on the ciliary epithelium, reducing cyclic AMP and thereby decreasing aqueous humor secretion by 20–35%.
Question 3: Which topical anesthetic is most commonly used for tonometry in optometric practice?
- Proparacaine 0.5% (Correct answer)
- Cocaine 4%
- Lidocaine 2%
- Tetracaine 1%
Correct answer: Proparacaine 0.5%
Proparacaine 0.5% is the most widely used topical ophthalmic anesthetic due to its rapid onset, short duration, and minimal stinging compared to other agents.
Question 4: Atropine 1% eye drops cause cycloplegia and mydriasis by:
- Blocking muscarinic receptors in the iris sphincter and ciliary body (Correct answer)
- Stimulating alpha-1 adrenergic receptors in the iris dilator
- Blocking beta receptors in the ciliary epithelium
- Activating nicotinic receptors in the extraocular muscles
Correct answer: Blocking muscarinic receptors in the iris sphincter and ciliary body
Atropine competitively blocks muscarinic (M3) receptors, preventing acetylcholine from stimulating the iris sphincter (causing mydriasis) and ciliary muscle (causing cycloplegia).
Question 5: Fluorescein dye in optometric practice is used primarily for:
- Applanation tonometry and contact lens fitting evaluation (Correct answer)
- Dilating the pupil for fundus examination
- Constricting the pupil before laser procedures
- Treating bacterial corneal ulcers
Correct answer: Applanation tonometry and contact lens fitting evaluation
Fluorescein sodium is a vital dye that fluoresces yellow-green under cobalt blue illumination, used to assess the tear film, fit RGP lenses, and measure IOP by applanation.
Question 6: The mechanism of action of carbonic anhydrase inhibitors (e.g., dorzolamide) in glaucoma treatment is:
- Inhibiting carbonic anhydrase II in the ciliary epithelium to reduce aqueous production (Correct answer)
- Increasing uveoscleral outflow by relaxing ciliary muscle
- Blocking alpha-2 receptors to reduce episcleral venous pressure
- Stimulating beta-1 receptors to increase trabecular outflow
Correct answer: Inhibiting carbonic anhydrase II in the ciliary epithelium to reduce aqueous production
CAIs inhibit carbonic anhydrase type II in the non-pigmented ciliary epithelium, reducing bicarbonate and sodium transport that drives aqueous secretion.
AOA Ocular Pharmacology 1
Prostaglandin analogs (e.g., latanoprost) lower intraocular pressure by: