Are dilating drops safe for patients with open angle glaucoma?

Dilating Drops in Open Angle Glaucoma: Safety Considerations

Dilating drops are generally safe for patients with open angle glaucoma, but should be used with caution as they can cause temporary intraocular pressure (IOP) elevation in some patients.

Safety Profile of Dilating Drops in Open Angle Glaucoma

Dilating drops have different safety profiles depending on the type of glaucoma:

• Open Angle Glaucoma: Generally safe but requires monitoring
• Angle Closure Glaucoma: Potentially dangerous and requires extreme caution

Risk Assessment for Open Angle Glaucoma Patients

Research has shown that pupillary dilation can cause IOP elevation in patients with primary open angle glaucoma:

• Approximately 32% of open angle glaucoma patients experience significant pressure elevation (>5 mmHg) after dilation 1
• About 12% experience marked pressure elevation (>10 mmHg) 1
• Patients on miotic medications are at higher risk for IOP spikes after dilation 1

Recommended Approach for Dilating Open Angle Glaucoma Patients

1. Pre-dilation Assessment:

   • Check baseline IOP
   • Perform gonioscopy to confirm open angles
   • Assess optic nerve status and disease severity

2. Dilation Procedure:

   • Use low-strength tropicamide when dilation is deemed essential (e.g., for suspected retinal pathology) 2
   • Consider avoiding stronger mydriatics like phenylephrine in high-risk patients
   • Be prepared to manage any IOP spikes that may occur

3. Post-dilation Monitoring:

   • Measure IOP 1 hour after dilation to detect pressure spikes
   • Be prepared to treat elevated IOP if necessary

Management of IOP Spikes

If IOP elevation occurs following dilation:

• Administer IOP-lowering medications (typically aqueous suppressants)
• Consider additional interventions if pressure remains elevated
• Schedule closer follow-up to ensure IOP returns to baseline

Special Considerations

• Advanced Glaucoma: Patients with severe optic nerve damage should be monitored more carefully as they have less reserve and are more vulnerable to pressure spikes
• Patients on Multiple Medications: Those already on maximum medical therapy may have limited options for managing pressure spikes
• Alternative Examination Methods: For high-risk patients, consider:
  • Non-mydriatic fundus photography
  • OCT imaging through undilated pupils 2

Contrast with Angle Closure Glaucoma

Unlike open angle glaucoma, pupil dilation in patients with narrow angles or angle closure glaucoma can precipitate acute angle closure crises (AACC) 2, 3. For these patients:

• Pupil dilation should be done only when absolutely necessary
• Laser peripheral iridotomy should be performed before routine dilated examinations
• If dilation is essential before iridotomy, it should be done with extreme caution and close monitoring 2

Bottom Line

While there is a potential risk of IOP elevation after dilation in open angle glaucoma patients, the benefits of a thorough retinal examination often outweigh these risks when proper precautions are taken. The key is appropriate patient selection, monitoring, and preparedness to manage any complications that may arise.