Background
Angle closure is defined as the apposition of iris to the trabecular meshwork, which results in increased intraocular pressure (IOP). In acute angle closure (AAC), the process occurs suddenly with a dramatic onset of symptoms, including blurred vision, red eye, pain, headache, and nausea and vomiting. The sudden and severe IOP elevation can quickly damage the optic nerve, resulting in acute angle-closure glaucoma (AACG).
AAC is a true ophthalmic emergency, and a delay in treatment can result in blindness. While immediate treatment can sometimes minimize the amount of visual loss, the best treatment is to stop its occurrence in susceptible individuals. [1, 2, 3, 4]
Pathophysiology
Primary angle-closure glaucoma (AAC) is uncommon in younger individuals but becomes more prevalent with age as the lens enlarges and potentially pushes the iris forward, narrowing the angle between the iris and the cornea. [5] This condition is influenced by several risk factors including genetic predisposition, advanced age, and ethnicity, with increased incidence noted in Asian and Inuit populations, and decreased incidence in European and African populations.
Clinically, narrow angles reduce the space between the iris at the pupil and the lens. During mid-dilation of the pupil, this space is minimized, facilitating contact between the iris and lens. [5] This contact impedes the flow of aqueous humor from the posterior to the anterior chamber, leading to pupillary block. Subsequent aqueous production by the ciliary body forces the peripheral iris to bow forward (iris bombe), closing the angle and obstructing aqueous outflow. This results in a rapid and significant elevation of intraocular pressure (IOP), often exceeding 40 mm Hg, which can swiftly lead to irreversible optic nerve damage and acute angle-closure glaucoma.
Acute angle-closure glaucoma demands immediate medical intervention to prevent rapid and irreversible vision loss. Intermittent angle-closure glaucoma may resolve temporarily, often after the patient has been supine, whereas chronic angle-closure glaucoma progresses slowly as the angle continues to narrow, leading to gradual scarring and increased IOP.
Pupillary dilation (mydriasis) can exacerbate angle narrowing and precipitate acute angle-closure glaucoma in individuals with predisposed narrow angles. [5] Secondary angle-closure glaucomas arise from mechanical obstructions related to other ophthalmic conditions such as proliferative diabetic retinopathy, ischemic central vein occlusion, uveitis, or epithelial down-growth, where neovascular membranes or inflammatory scarring pull the iris into the angle, worsening the closure.
Additional factors contributing to primary angle closure include plateau iris configuration, certain medications, increased iris thickness, dilation-induced iris volume increase, hyperopia, and lens thickening in phacomorphic angle closure. These clinical observations underscore the importance of vigilant monitoring and management in patients at risk for angle-closure glaucoma.
Epidemiology
In the United States, an estimated 3 million individuals are affected by glaucoma.
Globally, glaucoma ranks as the second leading cause of blindness. The worldwide prevalence of acute angle-closure glaucoma (AACG) is approximately 0.6%, with variations observed across different ethnic groups. [6] AACG prevalence increases with age, particularly among individuals over 40 years. It is more prevalent among Inuit and Asian populations, less so among Whites, and is least common among Blacks. Although AACG constitutes a minor fraction of all glaucoma cases globally (0.6%, equating to roughly 17 million individuals), it represents a substantial proportion of cases in Eastern and Southeast Asian populations, affecting about 12 million individuals. AACG is more frequently diagnosed in women and those with hyperopia. A family history of AAC or prior occurrence of AAC in one eye also significantly increases the risk. [2, 6, 7]
Prognosis
The prognosis is favorable with early detection and treatment. The best way to prevent loss of vision is to treat susceptible individuals prior to AAC.
Patient Education
AAC is a medical emergency that must be treated immediately. Even with immediate treatment, AAC may result in vision loss. The best method for preventing vision loss due to AAC is prophylactic treatment in patients with susceptible anatomy.
Patients need to promptly seek an eye care professional if symptoms (pain, decreased vision, headache, and vomiting) suggest AAC.
Tables
What would you like to print?
- FDA Approves Implant for Glaucoma
- A Better Way to Assess Glaucoma?
- Stiff Arteries Can Predict Risk for Glaucoma
-
Association for Research in Vision and Ophthalmology (ARVO) 2025 Annual Meeting
-
Glaucoma: A Hidden Threat to Vision Health Rising Swiftly
-
American Academy of Ophthalmology (AAO) 2023 Annual Meeting
