How To Break An Acute
Angle Closure Attack

by Christopher J. Quinn, O.D.

A 68-year-old white female presents to your office with a 5-day history of increasing pain, redness, photophobia, headache and blurred vision O.D. She awoke this morning with nausea and vomited prior to coming in.

Your examination reveals decreased acuity in the right eye, corneal edema and a mid-dilated and poorly reactive pupil in the left eye. Intraocular pressure is 76mm Hg O.D., 19mm Hg O.S. There is no iris rubeosis and, although gonioscopy is difficult due to corneal edema, no angle structures are visible.

The diagnosis in this case is easy: acute angle closure glaucoma. The hard part is the next step, breaking the attack with appropriate medical treatment. Where do you begin?

Reduce IOP With Orals
In this case, especially since the angle closure has been in progress for a prolonged period, you'll need more than topical treatment alone. Your first step should be to administer an oral carbonic anhydrase inhibitor. Give 500mg acetazolamide (Diamox) in two 250mg tablets. (Avoid using a 500mg sequel capsule; it's a sustained-release preparation and won't act as quickly as the 250mg tablets.)

Be aware of the potential contraindications of the oral carbonic anhydrase inhibitors. Use these agents with caution in patients who are already dehydrated, have severe congestive heart failure, or are taking potassium-depleting drugs. Still, the potential benefit of this emergency treatment will most likely outweigh the potential for side effects, which can include nausea, vomiting, severe headache and disorientation or confusion. Keep in mind that most CAI side effects come with chronic use. Short-term use is generally safe and effective.

Next, administer an oral hyperosmotic agent, preferably Osmoglyn (glycerin) in a dose of 1.0-1.5gm/kg (4-6 ounces of 50% solution). In diabetic patients, substitute isosorbide (Ismotic).

Hyperosmotics act as systemic dehydrating agents and are essential for reducing IOP. Rapid administration of these agents can result in vomiting, so administer the drug slowly. Even better, mix the dosage with fruit juice and serve over ice. Have the patient ingest this slowly with little sips. Drinking with a straw may help. Expect a significant effect in 60-90 minutes.

Add Topical Agents
Once you've instituted oral treatment, start topical treatment with a beta-blocker and pilocarpine 2%. Stronger miotic agents may actually cause the anterior chamber to shallow further and make it more difficult to break the attack.

Refine your topical regimen to avoid potential side effects from these agents. Xalatan (latanoprost) won't help, since its effect is not rapid. Alpha-agonists may cause mydriasis. Topical CAIs won't contribute much since you've already administered oral CAIs. You might administer a few drops of prednisolone acetate 1% to reduce the associated inflammatory reaction and make the patient more comfortable.

Once you've started the medications, have the patient wait for 60 minutes and then recheck IOP, which should lower. When the IOP gets below 40mm Hg, the pilocarpine may take effect. Once the pupil constricts and the IOP normalizes, gonioscopy should reveal some angle structures, although peripheral anterior synechiae may be present.

Consider the attack broken once the pupil is miotic. Schedule the patient for definitive treatment with laser iridotomy. Remember that the acute angle closure attack may damage the trabeculum. So despite a patent iridotomy, the patient may need ongoing treatment to reduce the IOP and prevent further damage to the optic nerve.