How should primary open‑angle glaucoma be initially managed in an adult patient?

Initial Management of Primary Open-Angle Glaucoma

Begin treatment immediately with a prostaglandin analog (latanoprost, bimatoprost, or travoprost) as first-line monotherapy, targeting a 20-30% reduction in intraocular pressure from baseline. 1, 2

First-Line Medication Selection

• Prostaglandin analogs are the optimal initial choice due to superior IOP-lowering efficacy (20-35% reduction), once-daily dosing that improves adherence, and minimal systemic side effects 2, 3

• Among prostaglandin analogs, bimatoprost demonstrates the greatest IOP reduction (5.61 mmHg), followed closely by latanoprost (4.85 mmHg) and travoprost (4.83 mmHg), though these differences are small and may not be clinically meaningful 3

• Beta-blockers like timolol are less effective (3.70 mmHg reduction) and carry contraindications in patients with asthma, COPD, or bradycardia 2, 3

• Alpha-2 agonists (brimonidine) and carbonic anhydrase inhibitors (dorzolamide, brinzolamide) are third-line options with lower efficacy 2, 3

Target IOP Setting

• Set initial target IOP at 20-30% below baseline measurement 1

• For a patient with baseline IOP of 30 mmHg, the initial target range would be 21-24 mmHg 2

• This target applies even to normal-tension glaucoma patients, as lowering IOP is beneficial regardless of baseline pressure 1

• Adjust target downward if disease progression occurs despite achieving initial target 1

Baseline Documentation Requirements

• Perform gonioscopy to confirm open anterior chamber angles and exclude secondary causes 1

• Document optic nerve head and RNFL status using both clinical examination and imaging (OCT or stereoscopic photography provide complementary information) 1

• Obtain baseline visual field testing with standard automated perimetry 1

• Look specifically for: disc rim notching at inferior/superior poles, RNFL thinning, disc hemorrhages, beta-zone parapapillary atrophy, and asymmetry between eyes 1

When Initial Monotherapy Is Insufficient

• Add a second medication from a different drug class (typically a beta-blocker if no contraindications, or a carbonic anhydrase inhibitor) 2

• Consider fixed-combination therapy (prostaglandin analog + timolol) which is more effective than either component alone 4

• Evaluate for selective laser trabeculoplasty as adjunctive or alternative therapy 2

Initial Combination Therapy Scenarios

• Consider starting with combination therapy (prostaglandin analog + beta-blocker) in specific situations: stage II-III disease with high baseline IOP, inability to ensure regular follow-up due to social/economic factors, or when rapid IOP control is critical 5

• Initial combination achieves target IOP faster (1.5 visits vs 2.5 visits) and in more patients (64% vs 59%) compared to stepwise monotherapy 5

Monitoring Schedule

• Reassess IOP, optic nerve structure, and visual fields regularly to detect progression 1

• Adjust target IOP downward if any deterioration in structure or function occurs despite meeting initial target 1

• Monitor for medication side effects: conjunctival hyperemia (3-15% with prostaglandin analogs) and permanent iris color change (2-9%) 4

Critical Pitfalls to Avoid

• Do not delay treatment while awaiting additional testing—early diagnosis and treatment prevent visual disability 1

• Do not assume normal IOP excludes glaucoma; nearly 40% of POAG patients have normal-range IOP measurements 1

• Do not prescribe beta-blockers without screening for asthma, COPD, bradycardia, or heart block 2

• Do not accept poor adherence—once-daily prostaglandin analogs specifically address this issue 2

• Do not fail to educate patients that this is a chronic, progressive disease requiring lifelong treatment and monitoring 1