Acute Primary Angle Closure Incidence Rising in North America

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The risk is especially elevated among women, individuals between 60 and 69 years of age, and those with Asian ethnicity.

The incidence of acute primary angle closure (APAC) is increasing in the United States, and is most common among women, individuals of lower socioeconomic status, and those between ages 60 and 69 years, according to research published in Clinical Ophthalmology.  

The Nationwide Emergency Department Sample (NEDS) was used to identify all people in the United States with primary diagnoses of APAC between January 2008 to December 2017. Participants were excluded if they were labeled as having intermittent, chronic, or residual angle closure. The incidence rate was calculated using US Census data and analysis was completed to identify national and regional trends, demographic factors of participants, seasonal variation on presentation, and costs of care per emergency department (ED) encounter and per year. 

During the 10-year period that this study took place, 23,203 APAC-related ED visits occurred. The mean age of participants was 58.8±16.2 years and APAC-related ED visits were most common among women (13,786, 59.4%, P <.01) and participants aged 60 to 69 years (5599, 24.1%), with the incidence of APAC increasing as age increased. Also, participants in the lowest income quartile were more likely to present with APAC than other income groups (6983, 30.1%, P <.01).

There was an average of 0.73 APAC-related ED visits per 100,000 population, with an annual increase of 0.04 cases per 100,000 population, showing significant increase in incidence during the study (P <.01, R2=0.83). Regional trend analysis showed the Northeast having the highest incidence rate (0.67 per 100,000 population). Seasonal trend analysis showed December as having the highest average incidence (0.067 per 100,000 population) and April having the lowest (0.049 per 100,000 population). The median annual charge of APAC-related ED visits was $2496.10 (IQR $1173.30–5271.40) and the total cost of these visits increased by an average of $1.09 million per year (P <.01). 

Results showing that first presentation occurs around 60 years and is more common among women and individuals with lower incomes is consistent with previous research conducted in other countries. 

Researchers hypothesize that the regional trends could be attributed to larger Asian populations in the Northeast, increased access to ED care, or differing climates. Similarly, they hypothesize that the seasonal trends can be attributed to weather and daily sunlight exposure. 

“Preventive strategies should be targeted towards these high-risk groups,” researchers explain. “Ophthalmologists should also be aware of the significant regional and seasonal trends in the presentation of APAC in the United States.”

The limitations of this study include the data available from NEDS, which is limited only to ED visits and does not include regular ophthalmology visits, follow-ups, or repeated ED visits. For this reason, patients with APAC who did not visit the ED and additional ophthalmologic diagnoses were not included in the results. NEDS also offers no data on patient race or specific location, limiting the results. 


Mehta SK, Mir T, Freedman IG, et al. Emergency department presentations of acute primary angle closure in the United States from 2008 to 2017. Clin Ophthalmol. 2022;16:2341-2351. doi:10.2147/OPTH.S368453