Ocular Pharmacology and Therapeutic Management
Pharmacology items test mechanism, contraindication, and monitoring rather than memorized dosages.
Glaucoma agents
Prostaglandin analogs increase uveoscleral outflow; side effects include iris darkening, eyelash growth, and periorbital fat atrophy, and they are avoided in active uveitis and pregnancy. Beta blockers reduce aqueous production but are contraindicated in asthma, COPD, and heart block. Alpha-2 agonists cause fatigue and dry mouth and must be avoided in young children because of CNS depression. Topical carbonic anhydrase inhibitors are sulfonamide-related; systemic forms cause paresthesias and hypokalemia. Pilocarpine causes miosis and brow ache and is used after IOP is lowered in angle closure.
Other classes
Cycloplegics: tropicamide is short-acting for dilation; cyclopentolate is used for cycloplegic refraction in children; atropine is longest and used for penalization and uveitis. Phenylephrine dilates without cycloplegia. Topical steroids vary in potency and raise IOP; taper rather than stop abruptly. Fluoroquinolones are first-line for bacterial keratitis; avoid long-term aminoglycosides. Preservative toxicity from benzalkonium chloride worsens with frequent dosing and soft lens wear.
Principles
Start one agent, allow four to six weeks for effect, then add or switch. Teach punctal occlusion to reduce systemic absorption. Pediatric dosing requires weight-based calculation and caution with combination drops.
Worked example
A 70-year-old with asthma and IOP of 26 needs treatment. Reasoning: avoid timolol because of reactive airway disease. Start latanoprost at bedtime, check IOP in four to six weeks, and if the target is unmet add dorzolamide or brimonidine rather than a beta blocker. Document the asthma in the record so future prescribers see it.
Traps
Prescribing a beta blocker to an asthmatic; using brimonidine in a toddler; missing steroid-induced pressure rise; and treating a dendritic ulcer with a steroid.