What medications can lower intraocular pressure (IOP)?

Medications to Lower Intraocular Pressure (IOP)

Prostaglandin analogs should be used as first-line therapy for lowering intraocular pressure due to their superior efficacy, once-daily dosing, and favorable safety profile. 1

First-Line Treatment Options

Prostaglandin Analogs (PGAs)

• Most effective drug class for IOP reduction (20-35% reduction)
• Mechanism: Increase uveoscleral outflow of aqueous humor 2
• Options include:
  • Bimatoprost 0.03% (highest efficacy within class)
  • Latanoprost 0.005%
  • Travoprost 0.004%
  • Tafluprost (less commonly used)
• Advantages:
  • Once-daily dosing (typically at night)
  • No significant systemic side effects
  • Superior efficacy compared to other classes 1
• Common side effects:
  • Conjunctival hyperemia (redness)
  • Eyelash growth
  • Periocular skin darkening
  • Iris color change (permanent)

Second-Line/Adjunctive Treatments

If target IOP is not achieved with a prostaglandin analog, consider adding or switching to:

Beta-Blockers

• IOP reduction: 15-25%
• Mechanism: Decrease aqueous humor production
• Options include:
  • Timolol 0.25% or 0.5% (non-selective)
  • Betaxolol 0.5% (cardioselective)
• Dosing: Once or twice daily
• Contraindications: Asthma, COPD, heart block, bradycardia

Alpha-2 Adrenergic Agonists

• IOP reduction: 15-20%
• Mechanism: Decrease aqueous production and increase uveoscleral outflow 3
• Options:
  • Brimonidine 0.1%, 0.15%, or 0.2%
• Dosing: Two to three times daily
• Side effects: Ocular allergic reactions, dry mouth, fatigue

Topical Carbonic Anhydrase Inhibitors

• IOP reduction: 15-20%
• Mechanism: Decrease aqueous humor production
• Options:
  • Dorzolamide 2%
  • Brinzolamide 1%
• Dosing: Two to three times daily
• Side effects: Stinging, bitter taste, allergic reactions

Rho Kinase Inhibitors

• IOP reduction: 10-20%
• Mechanism: Increase trabecular outflow, decrease episcleral venous pressure
• Options:
  • Netarsudil 0.02%
• Dosing: Once daily
• Side effects: Conjunctival hyperemia, corneal verticillata

Combination Therapy

When monotherapy is insufficient, fixed-combination medications can improve efficacy and adherence 4:

• PGA + Timolol combinations (once daily)
• Dorzolamide + Timolol (twice daily)
• Brimonidine + Timolol (twice daily)

Comparative Efficacy

Direct comparisons show:

• Latanoprost reduces IOP more effectively than brimonidine (5.7 vs 3.1 mmHg reduction) 5
• Latanoprost reduces IOP more effectively than timolol (26.8% vs 19.9% reduction) 6
• Bimatoprost appears to have slightly greater efficacy than latanoprost (2.59-5.60% greater IOP reduction) 7

Clinical Pearls and Pitfalls

• Target IOP: Aim for at least 20% reduction from baseline IOP 1
• Adherence challenges: Consider once-daily medications (PGAs) to improve compliance
• Monitoring: Distinguish between medication effect and normal IOP fluctuations by comparing to multiple baseline measurements
• Side effect management:
  • Hyperemia tends to decrease over time with continued use
  • Instruct patients about potential iris color changes with PGAs
  • For patients with respiratory conditions, avoid beta-blockers
• Cost considerations: Generic latanoprost may be more affordable than newer PGAs with similar efficacy

Special Populations

• Normal tension glaucoma: PGAs (particularly latanoprost) have shown efficacy even in the lower IOP range typical of NTG 8
• Pregnancy: Consider risk/benefit - most glaucoma medications are FDA pregnancy category C
• Elderly patients: Be cautious with beta-blockers due to potential systemic effects

By following this evidence-based approach to IOP reduction, you can effectively manage ocular hypertension and glaucoma while minimizing side effects and maximizing patient adherence.