What is the best approach to managing elevated intraocular pressure (IOP)?

Management of Elevated Intraocular Pressure

Prostaglandin analogs should be used as first-line medical therapy for elevated intraocular pressure (IOP) unless contraindicated due to their superior efficacy, once-daily dosing, and favorable side effect profile. 1

Initial Medical Therapy Selection

First-Line Therapy

• Prostaglandin analogs (PGAs) are the most efficacious and well-tolerated medications for lowering IOP:
  • Reduce IOP by 25-30% on average 2
  • Work by increasing uveoscleral and trabecular outflow
  • Once-daily evening dosing improves adherence
  • Examples: latanoprost 0.005%, travoprost 0.004%, bimatoprost 0.03%
  • Latanoprost's effect is proportional to untreated IOP above 16 mmHg 3

Second-Line Options

If PGAs are contraindicated or insufficient:

• Beta-adrenergic antagonists (e.g., timolol 0.5%)

  • Reduce IOP by 20-30% by decreasing aqueous production 4
  • Dosed once or twice daily
  • Avoid nighttime dosing due to reduced efficacy and potential systemic effects
  • Contraindicated in patients with asthma, COPD, heart block, or bradycardia

• Alpha-2 adrenergic agonists (e.g., brimonidine)

  • Useful for short-term IOP control and preventing IOP spikes after laser procedures 5

• Carbonic anhydrase inhibitors (topical or oral)

  • Decrease aqueous production
  • Useful as adjunctive therapy

Target IOP Determination

The goal of treatment is to maintain IOP at a level that prevents optic nerve damage and visual field loss:

• For glaucoma suspects or ocular hypertension: Target 20% reduction from baseline 1
• For established glaucoma: Target depends on disease severity, with lower targets for advanced disease
• Reassess target IOP periodically based on optic nerve status and visual field tests
• Consider more aggressive targets if risk factors for progression are present (e.g., disc hemorrhages, thin central cornea)

Treatment Algorithm

1. Initial Assessment:

   • Measure baseline IOP (preferably with Goldmann applanation tonometry) 6
   • Determine if primary open-angle glaucoma (POAG) or angle-closure glaucoma
   • Assess for risk factors for progression

2. For Open-Angle Glaucoma or Ocular Hypertension:

   • Start with PGA monotherapy (once daily in the evening) 1
   • Check IOP after 3-4 weeks to assess response
   • If target IOP achieved: continue and monitor
   • If target IOP not achieved: either switch to different PGA or add second medication

3. For Combination Therapy:

   • Add beta-blocker, alpha-2 agonist, or carbonic anhydrase inhibitor
   • Consider fixed-combination products to improve adherence 7
   • PGA-timolol fixed combinations are more effective than monotherapy with either component alone

4. For Acute Angle-Closure Glaucoma:

   • Immediate medical therapy to lower IOP rapidly 5
   • Use combination of beta-blockers, alpha-2 agonists, and carbonic anhydrase inhibitors
   • Consider hyperosmotic agents for severe elevation
   • Perform laser peripheral iridotomy as definitive treatment once cornea clears 1, 5

5. If Medical Therapy Fails:

   • Consider laser trabeculoplasty for open-angle glaucoma
   • Consider surgical intervention (trabeculectomy or tube shunt)
   • For angle-closure glaucoma with persistent IOP elevation after iridotomy, consider lens extraction 1

Special Considerations

For Primary Angle-Closure Disease

• Laser peripheral iridotomy is the definitive treatment to eliminate pupillary block 1
• If IOP remains elevated after successful iridotomy:
  • Consider other mechanisms (plateau iris, phacomorphic)
  • Treat with medical therapy similar to open-angle glaucoma
  • Consider lens extraction, especially with coexisting cataract 1

Monitoring Treatment Effectiveness

• Measure IOP at appropriate intervals based on disease severity and control
• Distinguish between therapeutic effect and normal IOP fluctuations 1
• Assess for progression of optic nerve damage and visual field loss
• Adjust therapy if target IOP not maintained or disease progresses

Common Pitfalls to Avoid

1. Underestimating the importance of adherence:

   • Once-daily medications and fixed combinations improve compliance
   • PGAs' once-daily dosing provides significant advantage

2. Overlooking contraindications:

   • Beta-blockers in patients with respiratory or cardiac conditions
   • Alpha-2 agonists in patients taking monoamine oxidase inhibitors

3. Ignoring ocular side effects:

   • PGAs: conjunctival hyperemia, eyelash growth, periocular pigmentation, iris color change
   • Beta-blockers: ocular surface disease
   • Monitor for and counsel patients about these effects

4. Missing angle-closure mechanisms:

   • Always perform gonioscopy to determine angle status
   • Don't assume all elevated IOP is open-angle glaucoma

5. Inadequate follow-up:

   • After initiating therapy, check IOP within 3-4 weeks
   • After laser peripheral iridotomy, check IOP within 1-2 hours and confirm patency 5

By following this structured approach to managing elevated IOP, focusing on prostaglandin analogs as first-line therapy when appropriate, and carefully monitoring response to treatment, most patients can achieve adequate IOP control and preservation of vision.