Ocular Pharmacology and Therapeutics
Core framework
Organize ophthalmic drugs by class and mechanism: anti-infectives, anti-inflammatories (steroids and NSAIDs), glaucoma agents, mydriatics/cycloplegics, anesthetics, and dry-eye/lubricant therapies. For each, know indication, key adverse effect, and contraindication.
Concepts to know cold
- Glaucoma agents: prostaglandin analogs (increased pigmentation, eyelash growth, periorbital fat atrophy), beta-blockers (bronchospasm, bradycardia; avoid in asthma), alpha-agonists (apraclonidine allergy, brimonidine fatigue), carbonic anhydrase inhibitors (sulfa allergy, metabolic acidosis), and pilocarpine (miosis, induced myopia).
- Mydriatics vs cycloplegics: phenylephrine dilates without cycloplegia; tropicamide and cyclopentolate cause cycloplegia. Atropine is longest-acting. Avoid anticholinergics in narrow angles.
- Steroids: know the risk of steroid-induced IOP rise, cataract, and infection masking. Taper chronic use.
- Anesthetics: topical proparacaine for procedures only, never for home use (corneal toxicity).
Traps
Questions test contraindications more than mechanisms. Remember beta-blockers and asthma, and sulfa allergy with CAIs. Distinguish additive IOP lowering from duplication of the same class.
Rule of thumb
For any new topical drug, ask: does it affect pupil size, accommodation, or systemic adrenergic/beta pathways? That single question resolves most side-effect items.
Worked example
A patient on timolol develops wheezing. Timolol is a nonselective beta-blocker; even topical dosing reaches systemic circulation and can bronchoconstrict. Answer: discontinue and switch class (e.g., prostaglandin analog).