Ocular Pharmacology and Medication Instillation
Core concepts
Know drug classes and their mechanisms: mydriatics and cycloplegics (anticholinergics like tropicamide and atropine vs. sympathomimetics like phenylephrine), topical anesthetics, anti-infectives, anti-inflammatories (steroids and NSAIDs), and glaucoma agents (beta-blockers, prostaglandin analogs, alpha agonists, carbonic anhydrase inhibitors, cholinergic agonists). Understand duration of action-tropicamide is short, atropine is long-and which agents cycloplege (paralyze accommodation) versus merely dilate. Learn proper instillation technique: hand hygiene, pulling down the lower lid to form a cul-de-sac, avoiding contact with the tip, punctal occlusion to reduce systemic absorption, and spacing multiple drops by about five minutes.
Traps
A frequent trap is confusing a mydriatic that does not cycloplege (phenylephrine) with one that does (tropicamide, cyclopentolate, atropine). Another is forgetting that punctal occlusion reduces systemic side effects, not ocular efficacy. Watch for questions on which drops are contraindicated in narrow angles and on the order of instillation when multiple drops are prescribed (instill aqueous before suspensions, wait between drops).
Worked example / rule of thumb
Rule of thumb: wait about five minutes between different drops-shorter intervals risk washout of the first medication. If a patient reports a bitter taste after drops, suspect nasolacrimal drainage and recommend punctal occlusion.
Study focus
Memorize systemic side effects of common agents (e.g., beta-blockers causing bronchospasm and bradycardia) and remember to check for allergies and to record instillation in the patient record.