What is the initial treatment for acute angle closure glaucoma?

Initial Treatment for Acute Angle Closure Glaucoma

The initial treatment for acute angle-closure glaucoma (AACG) should be prompt medical therapy to lower intraocular pressure (IOP), followed by laser peripheral iridotomy (LPI) as soon as possible to provide definitive treatment. 1

Medical Management (First-Line)

Medical therapy aims to rapidly lower IOP to relieve symptoms and clear corneal edema, making subsequent laser treatment possible. The recommended medications include:

• Topical medications:

  • Beta-adrenergic antagonists (e.g., timolol)
  • Alpha2-adrenergic agonists (e.g., brimonidine)
  • Carbonic anhydrase inhibitors (e.g., dorzolamide)

• Systemic medications:

  • Oral/IV carbonic anhydrase inhibitors (acetazolamide 250-500mg) 2, 3
  • Oral/IV hyperosmotic agents (e.g., mannitol) if needed for severe cases

• Important considerations:

  • Parasympathomimetics (miotics like pilocarpine) may be ineffective in AACG when IOP is markedly elevated due to pressure-induced ischemia of the pupillary sphincter 4
  • Agents that suppress aqueous humor formation may have decreased effectiveness initially if the ciliary body is ischemic 1
  • Corneal indentation with a gonioscopic lens, cotton-tipped applicator, or muscle hook may help break pupillary block temporarily 1

Definitive Treatment

Once IOP is lowered and corneal edema clears:

• Laser peripheral iridotomy (LPI) should be performed as soon as possible 1

  • Creates a bypass for aqueous humor
  • Eliminates pressure gradient between posterior and anterior chambers
  • Prevents or retards formation of peripheral anterior synechiae (PAS)
  • Results in significant angle widening and iris-profile flattening

• If LPI cannot be performed:

  • Try topical hyperosmotic agents to clear cornea
  • Consider anterior chamber paracentesis
  • Consider peripheral laser iridoplasty
  • Surgical iridectomy may be necessary if laser approaches fail

Management Algorithm

1. Initial assessment:

   • Confirm diagnosis (symptoms: eye pain, headache, nausea/vomiting, blurred vision, halos)
   • Check IOP (typically markedly elevated)
   • Observe for corneal edema, mid-dilated pupil, conjunctival injection

2. Immediate medical therapy:

   • Administer topical beta-blockers, alpha2-agonists, and carbonic anhydrase inhibitors
   • Give oral/IV acetazolamide 250-500mg
   • Consider hyperosmotic agents for severe cases

3. Monitor response:

   • Check IOP within 1-2 hours
   • Assess corneal clarity

4. Definitive treatment:

   • Perform LPI as soon as cornea clears
   • Ensure patency by visualizing fluid flow or directly observing structures behind the iris
   • Aim for iridotomy size of at least 100 microns

5. Post-iridotomy care:

   • Prescribe topical corticosteroids
   • Check IOP within 30 minutes to 2 hours post-procedure
   • Schedule follow-up to confirm iridotomy patency and assess angle

Fellow Eye Management

The fellow eye should receive prophylactic LPI promptly if anatomically narrow, as approximately half of fellow eyes develop AACG within 5 years 1. Chronic parasympathomimetic therapy is not an appropriate alternative to iridotomy for prophylaxis.

Pitfalls and Caveats

• Don't delay definitive treatment: Prolonged high IOP can cause permanent damage to the optic nerve, trabecular meshwork, iris, lens, and cornea
• Don't overlook secondary causes: After iridotomy, persistent IOP elevation may be due to plateau iris syndrome, phacomorphic angle closure, or other mechanisms 1, 4
• Don't assume all treatments work equally: Filtering surgery in eyes with unbroken AACG has high risk of anterior chamber shallowing postoperatively 1
• Don't miss medication-induced AACG: Various medications can precipitate AACG, including adrenergic agents, anticholinergics, and sulfa-based drugs 5, 6
• Don't forget lens extraction: In some cases, lens extraction may be an effective treatment option for PAC and PACG, especially in older patients 1

By following this approach, you can effectively manage acute angle closure glaucoma, preventing permanent vision loss and reducing the risk of recurrence.