PRC Ocular Pharmacologist cheat sheet

Ocular Pharmacology

• Aqueous humor inflow: ciliary epithelium secretes via Na+/K+-ATPase, carbonic anhydrase, and Cl- channels; outflow via trabecular (pressure-dependent, ~80-90%) and uveoscleral (pressure-independent, ~10-20%) routes.

• Prostaglandin F2α analogs (latanoprost, travoprost, bimatoprost, tafluprost) lower IOP mainly by increasing uveoscleral outflow; adverse effects include iris hyperpigmentation, eyelash lengthening, and periorbital fat atrophy.

• Beta-blockers (timolol, betaxolol) reduce aqueous production via β2 receptors on ciliary epithelium; contraindicated in asthma, COPD, and second/third-degree heart block; betaxolol is β1-selective.

• Alpha-2 agonists (brimonidine, apraclonidine) reduce aqueous production and increase uveoscleral outflow; brimonidine causes follicular conjunctivitis and allergic blepharoconjunctivitis in up to 10-15% of patients.

• Carbonic anhydrase inhibitors (dorzolamide, brinzolamide, acetazolamide) inhibit HCO3- formation in ciliary epithelium, reducing aqueous secretion; topical forms avoid systemic acidosis and hypokalemia.

• Cholinergic agonists (pilocarpine) increase trabecular outflow via ciliary muscle contraction; side effects include miosis, induced myopia, and brow ache; contraindicated in acute iritis.

• Rho kinase inhibitors (netarsudil) increase trabecular outflow and reduce episcleral venous pressure; adverse effects include conjunctival hyperemia and cornea verticillata.

• Osmotic agents (mannitol IV, glycerol PO) draw water from vitreous and aqueous; used for acute angle-closure crisis; monitor for fluid overload and hyperglycemia.

• Fixed-combination drops (e.g., dorzolamide-timolol, brimonidine-timolol, latanoprost-timolol) improve adherence and reduce preservative exposure; avoid combining two prostaglandins.