What is the recommended first‑line therapy for an adult with primary open‑angle glaucoma and no other comorbidities?

First-Line Therapy for Primary Open-Angle Glaucoma

Prostaglandin analogs are the recommended first-line medical therapy for adults with primary open-angle glaucoma and no comorbidities, as they provide the most effective IOP reduction with once-daily dosing and superior tolerability. 1

Target IOP Reduction

The initial treatment goal is to reduce IOP by 20-30% below baseline levels to slow disease progression and preserve visual function. 1, 2 This target should be adjusted based on disease severity and progression during follow-up. 1

Why Prostaglandin Analogs First

• Most efficacious: Prostaglandin analogs provide superior IOP-lowering compared to other medication classes 1
• Best tolerability profile: Fewer systemic side effects than alternatives 1
• Convenient dosing: Once-daily administration improves adherence 1
• Evidence-based: Clinical trials demonstrate that lowering IOP reduces risk of developing POAG and slows progression 1

Alternative First-Line Options

If prostaglandin analogs are contraindicated, refused, or not tolerated, topical beta-adrenergic antagonists (such as timolol) are the next consideration. 1

Beta-Blocker Considerations:

• Provide 15-20% IOP reduction 1
• Avoid nighttime dosing: Associated with limited efficacy and may contribute to visual field progression via nocturnal blood pressure reduction 1
• Contraindicated in asthma/COPD: Non-selective beta-blockers can cause bronchospasm 1, 2
• If beta-blocker needed in pulmonary disease: Consider cardioselective betaxolol, which targets beta-1 receptors and minimizes pulmonary effects 1, 2

Other Medical Options

Additional medication classes include: 1

• Alpha-2 adrenergic agonists
• Topical carbonic anhydrase inhibitors (brinzolamide, dorzolamide)
• Rho kinase inhibitors (netarsudil)
• Oral carbonic anhydrase inhibitors (for short-term use)

When to Consider Laser or Surgery

Laser trabeculoplasty and surgical interventions are reserved for inadequate medical response, not as first-line therapy. 2

• Laser trabeculoplasty: 30-38% IOP reduction 2
• Trabeculectomy: 46-60% IOP reduction but higher surgical risks 2

Essential Baseline Documentation

Before initiating therapy, obtain: 1, 2

• Gonioscopy to confirm open angles
• Central corneal thickness measurement
• Baseline optic nerve imaging (OCT of optic nerve head, RNFL, and macula)
• Visual field testing with standard automated perimetry
• Multiple IOP measurements to establish baseline

Critical Pitfalls to Avoid

• Normal-tension glaucoma: Nearly 40% of POAG patients have "normal" IOP during office measurements but still require treatment and benefit from IOP reduction 1, 2
• Medication adherence: Up to 45% of patients take less than 75% of prescribed doses—emphasize importance at every visit 2
• High-risk populations: African Americans and Latinos/Hispanics have 3-fold higher POAG prevalence and warrant more aggressive monitoring 2
• Avoid systemic corticosteroids when possible in patients with family history of glaucoma due to steroid-responsiveness risk 2

Monitoring Strategy

Regular follow-up assessment must include: 1

• IOP measurement at each visit
• Optic nerve examination
• Visual field testing (frequency based on disease severity)
• Imaging of optic nerve head, RNFL, and macula to detect progression