A 62-year-old Indian male with newly diagnosed primary open-angle glaucoma is being counselled about management options. His IOP is 28 mmHg, and optic disc shows mild cupping with early superior arcuate visual field defect. Regarding medical management of POAG, all of the following statements are true EXCEPT:

Explanation

## Medical Management of Primary Open-Angle Glaucoma ### Why Beta-Blockers Are NOT Contraindicated **Key Point:** Beta-blockers (timolol 0.5%) are NOT contraindicated in all patients with POAG. They remain a safe and effective first-line agent in many patients, particularly those without systemic contraindications (asthma, COPD, bradycardia, heart block, decompensated heart failure). **High-Yield:** Beta-blockers are among the most widely used and cost-effective agents in POAG management globally, especially in resource-limited settings. While they have systemic side effects (bronchospasm, bradycardia, fatigue), these are manageable and do not apply universally. ### Pharmacological Agents in POAG: Mechanism and Efficacy | Agent Class | Mechanism | IOP Reduction | Role | Notes | |---|---|---|---|---| | Prostaglandin analogs | ↑ Uveoscleral outflow | 25–35% | **First-line** | Latanoprost, travoprost, bimatoprost; once daily; darkens iris/lashes | | Beta-blockers | ↓ Aqueous production | 20–25% | First-line (selective use) | Timolol; systemic side effects in susceptible patients; NOT contraindicated universally | | Carbonic anhydrase inhibitors (topical) | ↓ Aqueous production | 15–20% | Adjunctive/combination | Dorzolamide, brinzolamide; useful in combination therapy | | Alpha-2 agonists | ↓ Aqueous production + ↑ uveoscleral outflow | 15–25% | Adjunctive | Brimonidine; tachyphylaxis may develop; useful in combination | | Rho kinase inhibitors | ↑ Conventional outflow + ↓ aqueous production | 20–30% | Newer first-line | Netarsudil; emerging agent with dual mechanism | **Clinical Pearl:** The "stepladder" approach in POAG: start with prostaglandin analog monotherapy; if target IOP not achieved, add a second agent (beta-blocker, CAI, or alpha-2 agonist); consider laser or surgery if medical therapy fails. ### Treatment Algorithm for POAG ```mermaid flowchart TD A[POAG Diagnosed]:::outcome --> B[Define target IOP] B --> C{Contraindications to PGA?}:::decision C -->|No| D[Start PGA monotherapy]:::action C -->|Yes| E[Start beta-blocker or CAI]:::action D --> F{IOP at target?}:::decision E --> F F -->|Yes| G[Maintain monotherapy]:::action F -->|No| H[Add second agent]:::action H --> I{IOP at target?}:::decision I -->|Yes| J[Continue combination]:::action I -->|No| K[Add third agent or laser/surgery]:::urgent ``` **Mnemonic for POAG Drug Classes:** **"ABCARN"** - **A**lpha-2 agonists (brimonidine) - **B**eta-blockers (timolol) - **C**arbonic anhydrase inhibitors (dorzolamide) - **A**nalogs (prostaglandin) - **R**ho kinase inhibitors (netarsudil) - **N**one = osmotic agents (for acute angle closure, not POAG) ### Why Beta-Blockers Remain Useful **Warning:** Do not confuse "systemic side effects exist" with "contraindicated in all patients." Beta-blockers are contraindicated only in patients with specific conditions (asthma, COPD, symptomatic bradycardia, 2nd/3rd degree heart block). In patients without these contraindications, beta-blockers remain safe, effective, and cost-effective.