How do stimulants affect acute angle glaucoma management?

Stimulants and Acute Angle-Closure Glaucoma Management

Stimulants should be avoided in patients with acute angle-closure glaucoma as they can precipitate or worsen attacks through pupillary dilation mechanisms, potentially leading to permanent vision loss.

Mechanism of Stimulant Effects on Angle-Closure Glaucoma

Stimulants, particularly those with adrenergic or sympathomimetic properties, can trigger or exacerbate acute angle-closure glaucoma (AACG) through several mechanisms:

• Pupillary dilation (mydriasis): Stimulants with adrenergic effects can cause pupillary dilation, which in anatomically predisposed eyes can precipitate angle closure 1, 2
• Anterior chamber narrowing: In patients with already narrow angles, the pupillary dilation can push the peripheral iris against the trabecular meshwork, blocking aqueous outflow 3
• Increased intraocular pressure (IOP): The resultant blockage leads to rapidly increasing IOP, which constitutes an ophthalmological emergency 4

High-Risk Medications to Avoid

The following stimulants and related medications should be avoided in patients with known narrow angles or previous AACG:

• Direct adrenergic agonists: Ephedrine, phenylephrine, and other sympathomimetics 2
• Inhaled bronchodilators: Salbutamol and other beta-adrenergic agonists 5
• Nasal decongestants: Containing ephedrine or pseudoephedrine 2
• ADHD medications: Amphetamine derivatives and methylphenidate due to their sympathomimetic effects

Clinical Evaluation of Patients on Stimulants

For patients requiring stimulant therapy who may be at risk for AACG:

1. Assess risk factors:

   • Hyperopia (farsightedness)
   • Advanced age
   • Asian ethnicity
   • Female gender
   • Family history of angle-closure glaucoma 3, 4

2. Perform gonioscopy to evaluate angle anatomy and identify patients with anatomically narrow angles 3

3. Monitor for early symptoms of angle closure:

   • Eye pain
   • Blurred vision
   • Halos around lights
   • Headache
   • Nausea/vomiting
   • Eye redness 3, 6

Management Algorithm for Patients Requiring Stimulants

1. For patients with confirmed narrow angles but no history of AACG:

   • Consider prophylactic laser peripheral iridotomy before initiating stimulant therapy 7
   • Regular monitoring of IOP and angle status if stimulants are necessary

2. For patients with history of AACG currently requiring stimulants:

   • First-line approach: Avoid stimulants completely if possible
   • If stimulants are absolutely necessary:
     • Ensure patient has had definitive treatment with laser peripheral iridotomy
     • Use the lowest effective dose of stimulant
     • Consider concurrent use of miotic agents (e.g., pilocarpine) to counteract pupillary dilation
     • Regular IOP monitoring during treatment 7

3. For acute management of stimulant-induced AACG:

   • Immediately discontinue the offending stimulant
   • Initiate IOP-lowering medications (beta-blockers, alpha-2 agonists, carbonic anhydrase inhibitors)
   • Perform laser peripheral iridotomy as soon as corneal clarity permits 7

Important Considerations and Pitfalls

• Bilateral risk: If one eye develops AACG, the fellow eye is at high risk and should receive prophylactic treatment 7
• Permanent damage: Prolonged elevated IOP can cause irreversible optic nerve damage and vision loss 3
• Medication reconciliation: Review all medications (including over-the-counter and supplements) for potential pupil-dilating effects 4
• Patient education: Patients with narrow angles should be educated about symptoms of AACG and instructed to seek immediate medical attention if they occur 6

Alternative Treatments

For patients with narrow angles or history of AACG who require treatment for conditions typically managed with stimulants:

• For ADHD: Consider non-stimulant options like atomoxetine, guanfacine, or bupropion
• For narcolepsy: Consider modafinil (which has less sympathomimetic activity) or sodium oxybate
• For depression: Avoid tricyclic antidepressants; consider SSRIs with lower anticholinergic effects

Remember that the risk of permanent vision loss from AACG must be weighed carefully against the benefits of stimulant therapy in these patients.