Antiglaucoma Medications

Glaucoma & IOP Targets - Eye Pressure Primer

• Glaucoma: Optic neuropathy: progressive RGC death, characteristic VF loss.
• Aqueous Humor (AH) Dynamics:
  • AH Production: Ciliary body (active secretion, ultrafiltration).
  • AH Outflow: Trabecular (80-90%), Uveoscleral (10-20%).
• Target IOP: ↓ 20-30% from baseline or specific target. Goldmann: $P_o = (F/C) + P_v$.

⭐ The two main mechanisms for IOP elevation are increased resistance to aqueous outflow (most common in POAG) or impaired access of aqueous to the drainage system (as in angle-closure glaucoma).

Prostaglandin Analogs - Lash Lengthening Lotions

• MOA: ↑ uveoscleral outflow. Bimatoprost: also minor ↑ trabecular.
• Drugs: 📌 'Lashes Long & Pretty'
  • Latanoprost, Travoprost, Bimatoprost, Tafluprost (PF).
  • Latanoprostene bunod (Latanoprost + NO).
• Side Effects (SE):

  • Common: Hyperemia, irreversible iris hyperpigmentation, eyelash growth, PAP (PG-associated periorbitopathy), skin hyperpigmentation.

  • Serious: CME (at-risk eyes, e.g., aphakic/pseudophakic), herpetic keratitis reactivation.

• Dose: 1x daily (evening).
• Pearls: 💡 Generally first-line for POAG.

⭐ Achieve greatest IOP ↓ (approx. 25-33%) among topical monotherapies for glaucoma., image_search_query="Eyelash growth and iris hyperpigmentation with prostaglandin analogs"

Beta-Blockers - Hearty Eye Helpers

• Mechanism: ↓ aqueous humor production (ciliary epithelium β-receptor blockade). 📌 Beta-Blockers Beat down aqueous Production.
• Types & Drugs:
  • Non-selective: Timolol, Levobunolol, Carteolol (ISA).
  • β1-selective: Betaxolol (safer in lung disease).
• Systemic SE: Bradycardia, hypotension, bronchospasm (non-selective), fatigue, masks hypoglycemia.
• Ocular SE: Stinging, dry eyes, allergy.
• Dosage: Timolol 0.5% BID. Tachyphylaxis possible.

⭐ Systemic absorption of topical beta-blockers is significant; nasolacrimal occlusion reduces this.

Alpha Agonists & CAIs - Dual Action Drops

📌 'ABC' for aqueous suppressants: Alpha agonists, Beta-blockers, CAIs.

Alpha-Adrenergic Agonists:

• Mechanism:
  • Brimonidine (α2): Dual action - ↓ aqueous production & ↑ uveoscleral outflow.
  • Apraclonidine (α2): Primarily ↓ aqueous production.
• Key Drugs: Brimonidine (0.1%, 0.15%, 0.2%); Apraclonidine (0.5%, 1% - short-term).
• Side Effects:
  • Allergic conjunctivitis (esp. Brimonidine), dry mouth, fatigue.
  • ⚠️ Brimonidine: CI in children <2 years (CNS depression/apnea).
  • Apraclonidine: Tachyphylaxis common.

Carbonic Anhydrase Inhibitors (CAIs):

• Mechanism: ↓ aqueous production (inhibits ciliary carbonic anhydrase).
• 
• Topical vs. Systemic CAIs:

  Type	Drugs (Examples)	Key Side Effects
  Topical	Dorzolamide (2%), Brinzolamide (1%)	Stinging, burning, SPK, bitter taste.
  Systemic	Acetazolamide, Methazolamide	Paresthesias, metallic taste, acidosis, hypokalemia, renal stones, aplastic anemia (rare). ⚠️ CI: Sulfa allergy.

⭐ Brimonidine: Potential neuroprotection (RGCs); clinical significance debated.

Miotics & Osmotics - Pupil Power Players

• Miotics (e.g., Pilocarpine 0.5-4%): 📌 "Mi PULLs" ciliary muscle, ↑ trabecular outflow.
  • Uses: Acute angle-closure glaucoma (AACG) after initial IOP ↓.
  • Side effects: Miosis (dim vision), accommodative spasm (brow ache). ⚠️ Retinal detachment risk.
• Hyperosmotic Agents: 📌 "Osmo DRAWS" water from vitreous via ↑ blood osmolality, rapidly ↓ IOP.
  • Mannitol (IV): 1-2 g/kg (20% sol).
  • Glycerol (Oral): 1-1.5 g/kg (50% sol). ⚠️ Caution: Diabetics.
  • Uses: Emergency IOP ↓ (AACG).

⭐ Pilocarpine in AACG only after IOP < 40-50 mmHg; ischemic iris may not respond or worsen closure.

High‑Yield Points - ⚡ Biggest Takeaways

• Prostaglandin analogs (Latanoprost): First-line; ↑ uveoscleral outflow. Key side effect: iris hyperpigmentation.
• Beta-blockers (Timolol): ↓ aqueous production. Contraindicated: asthma, heart block.
• Alpha-agonists (Brimonidine): Dual mechanism (↓ production, ↑ outflow). Risk: tachyphylaxis.
• CAIs (Dorzolamide): ↓ aqueous production. Systemic: sulfa allergy caution.
• Miotics (Pilocarpine): ↑ trabecular outflow. Cause miosis, accommodative spasm.
• Hyperosmotics (Mannitol): For acute angle-closure glaucoma; rapidly ↓ IOP.
• Netarsudil (Rho kinase inhibitor): Newest class; ↑ trabecular outflow.