From the Guidelines
Acute angle closure glaucoma is a serious eye emergency requiring immediate medical attention, and the initial treatment typically involves medications to lower intraocular pressure, followed by laser peripheral iridotomy to create a small hole in the iris, allowing fluid to flow properly, as recommended by the most recent guidelines 1. The condition occurs when the drainage angle in the eye suddenly becomes blocked, causing rapid pressure buildup that can damage the optic nerve and lead to vision loss if not treated promptly. Symptoms include severe eye pain, headache, blurred vision, seeing halos around lights, nausea, vomiting, and redness of the eye.
- Initial treatment involves medications to lower intraocular pressure, including:
- Eye drops such as timolol 0.5% (one drop in the affected eye), brimonidine 0.2% (one drop), and pilocarpine 2% (one drop every 15 minutes for four doses)
- Oral or intravenous medications, including acetazolamide 500mg orally or IV, followed by 250mg four times daily, and osmotic agents like mannitol 1-2g/kg IV over 45 minutes in severe cases
- Once the pressure is controlled, laser peripheral iridotomy is usually performed to create a small hole in the iris, allowing fluid to flow properly, as it has a favorable risk-benefit ratio and can prevent or retard the formation of peripheral anterior synechiae (PAS) 1. The unaffected eye often receives preventive treatment as well, since there's a high risk of developing the condition in both eyes. This condition occurs because the iris bulges forward, blocking the drainage angle where fluid normally exits the eye, and is more common in farsighted individuals, those of Asian or Inuit descent, and older adults, particularly women.
- The clinical objectives for managing acute angle closure glaucoma include:
- Identifying patients who currently have or are at risk of developing primary angle closure glaucoma (PACG) or acute angle-closure crisis (AACC) by using gonioscopy
- Successfully managing AACC
- Preventing or reversing angle closure by using laser iridotomy and/or iridoplasty when indicated, and by using incisional iridectomy when necessary to alleviate pupillary block 1.
From the FDA Drug Label
For adjunctive treatment of: ... preoperatively in acute angle-closure glaucoma where delay of surgery is desired in order to lower intraocular pressure. The preferred dosage is 250 mg every four hours, although some cases have responded to 250 mg twice daily on short-term therapy In some acute cases, it may be more satisfactory to administer an initial dose of 500 mg followed by 125 or 250 mg every four hours depending on the individual case.
Acetazolamide is used for the adjunctive treatment of acute angle-closure glaucoma. The dosage may vary from 250 mg every four hours to an initial dose of 500 mg followed by 125 or 250 mg every four hours depending on the individual case 2, 2.
From the Research
Definition and Causes of Acute Angle Closure Glaucoma
- Acute angle closure glaucoma is a sight-threatening situation characterized by a sudden and marked rise in intraocular pressure (IOP) due to obstruction of aqueous humour outflow 3.
- The most common primary cause is a pupillary block in patients with pre-existing narrow angles, such as those who are long-sighted 4.
- Secondary causes of angle closure include the use of commonly prescribed medications, such as sympathomimetics and beta agonists 5.
Symptoms and Diagnosis
- Symptoms of acute angle closure glaucoma include sudden onset of red eye associated with pupillary dilation, dull pain, and headache 4.
- Basic examination of the eye should include assessment of the anterior segment with a bright light, measurement of intraocular pressure, and a full neurological exam 4.
- A detailed interrogation is essential to exclude other possible confounding disorders that present similarly, especially those originating in the CNS 4.
Treatment and Management
- Immediate treatment must be initiated whenever there is high clinical suspicion of acute angle closure, with the administration of systemic ocular hypotensive therapy to prevent damage to the optic nerve and limit visual loss 4.
- The hypotensive effect of intramuscular or intravenous acetazolamide with frequent instillation of pilocarpine can be effective in treating acute closed-angle glaucoma 6.
- Topical timolol alone may not be effective enough to control the intraocular pressure in acute closed-angle glaucoma, but a good hypotensive effect can be seen when topical timolol is followed by pilocarpine 6.
- Prophylactic laser iridotomy should be performed at the earliest possible juncture to prevent acute angle closure glaucoma in the fellow eye 7.
High-Risk Groups and Prevention
- Critical care patients are at particular risk for the development of acute angle closure glaucoma due to the use of predisposing medications and sedation, which can lead to delayed diagnosis 5.
- A high index of suspicion is required to diagnose acute angle closure glaucoma in sedated patients 5.
- Awareness should be raised to identify secondary causes of angle closure, including the use of commonly prescribed medications 4.