What is the effect of prednisone on intraocular pressure (IOP) in patients with glaucoma?

Prednisone and Glaucoma: Risks and Management

Prednisone can cause significant elevation of intraocular pressure (IOP) in patients with glaucoma, potentially worsening disease progression and vision loss, and should be used with extreme caution in this population. 1, 2

Mechanism and Risk

Prednisone and other corticosteroids can induce or exacerbate glaucoma through several mechanisms:

• Increased resistance to aqueous humor outflow through the trabecular meshwork
• Morphological and functional changes in the trabecular meshwork system
• Excessive production of myocilin protein (transcribed by the GLC1A gene) 3
• Accumulation of extracellular matrix material in the trabecular meshwork

Risk Factors for Steroid-Induced IOP Elevation

The risk of corticosteroid-induced IOP elevation varies significantly among individuals, with certain populations at much higher risk:

• Patients with existing primary open-angle glaucoma (POAG): 46-92% are steroid responders 3
• General population: 18-36% are steroid responders 3
• Additional risk factors:
  • Age over 40 years
  • Family history of POAG
  • Diabetes mellitus
  • High myopia
  • African ancestry or Latino/Hispanic ethnicity 4
  • Thin central cornea

Clinical Implications

The IOP elevation from prednisone:

• Is dose-dependent and duration-dependent
• Can occur with any route of administration (oral, topical, periocular, or systemic)
• May lead to further optic nerve damage in patients with already compromised optic nerves
• Can cause underestimation of IOP in patients who have had LASIK surgery 5
• May develop into pressure-induced intralamellar stromal keratitis in post-LASIK patients 5

Monitoring and Management

For patients with glaucoma who require prednisone:

1. Baseline assessment: Document IOP, optic nerve status, and visual fields before starting therapy
2. Regular monitoring: Schedule frequent IOP checks after initiating prednisone
3. IOP-lowering medications: Consider prophylactic or therapeutic use of glaucoma medications
4. Target IOP: Aim for at least 20-25% reduction from baseline IOP 4
5. Medication options:
   • First-line: Prostaglandin analogs (most effective for IOP reduction) 4
   • Second-line: Beta-blockers, alpha-2 adrenergic agonists, carbonic anhydrase inhibitors

Prevention Strategies

To minimize risk of steroid-induced glaucoma:

• Use the lowest effective dose and shortest duration of prednisone therapy
• Consider alternative non-steroidal anti-inflammatory agents when possible
• Educate patients about symptoms of elevated IOP (eye pain, headache, blurred vision)
• Ensure patients understand the importance of regular IOP monitoring
• Consider discontinuing nasal steroids in patients with glaucoma, as even this route can increase IOP 6

Special Considerations

• Post-surgical patients: Despite concerns about prednisone's effect on IOP, studies have shown that postoperative steroids after trabeculectomy can actually improve long-term IOP control and disease stability 7
• LASIK patients: Prednisone can cause interface fluid accumulation and lead to IOP underestimation in post-LASIK patients 5
• Keratorefractive surgery: Patients with glaucoma considering keratorefractive surgery should be informed about potential IOP measurement inaccuracies after these procedures 5

Clinical Decision-Making

When considering prednisone for a patient with glaucoma:

1. Assess risk-benefit ratio carefully
2. Document baseline optic nerve and visual field status
3. Establish a clear monitoring plan
4. Set target IOP and have a plan for additional IOP-lowering interventions if needed
5. Consider alternative anti-inflammatory options when appropriate

By understanding these risks and implementing proper monitoring and management strategies, the potential vision-threatening complications of prednisone use in glaucoma patients can be minimized.