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Editors Selection IGR 26-1
Epidemiology: Prevalence and risk factors of angle-closure disease in Chinese Americans
Comment by David Friedman on:
126811 Prevalence and Risk Factors of Primary Angle Closure Disease in an Adult Chinese American Population: The Chinese American Eye Study, Xu BY; Richter GM; Burkemper BS et al., American Journal of Ophthalmology, 2025; 274: 32-41
Xu et al. present a rigorous, population-based assessment of primary angle-closure disease (PACD) among Chinese Americans. Among 4,310 examined adults aged 50 years or older, adjusted prevalences were PACS 8.3%, PAC 3.2%, and PACG 1.1% when using a gonioscopic angle closure of 270 degrees or more to define a closed angle. Rates were higher when using 180 degrees, as is currently more widely used. When the researchers appropriately included a "suspected PACG" (sPACG) category to account for eyes whose angles were widened by previous LPI or cataract surgery, the combined prevalence of PACG and sPACG was 1.8%.
Despite greater access to eye care—with pseudophakia in 9.9% of study participants versus 0.9%–2.9% in comparable Chinese mainland cohorts—PACG prevalence was similar to that reported in China. Visual morbidity was strikingly low: only one case of unilateral blindness and none of bilateral blindness, even though three-quarters of PACG cases were previously undiagnosed. Why blindness was so uncommon is difficult to explain in this cohort given the fact that many were not aware of having glaucoma.
Multivariable modeling identified older age (OR≈1.06/year), higher IOP (≈1.17/mmHg), positive family history (≈3.2), and anterior-segment crowding (shorter AL or shallower ACD) as independent PACG risks; sex was significantly associated with PACD, but not with PACG. Women have typically had two to three times the rate of PACG, so this is also a unique finding and once again, difficult to explain. These findings reinforce the central role of biometry in risk stratification and screening.
A definitional issue merits discussion. The researchers used the traditional ≥270° gonioscopic threshold to define PACS/PACG. Subsequent literature has argued that a ≥180° standard is more appropriate. The authors demonstrate that relaxing to 2 quadrants increased PACG prevalence by nearly 20%, from 1.1% to 1.3%, in this cohort. In contemporary practice—especially for triage and screening—lower quadrant thresholds (e.g., 180°, and perhaps even 90°) may better capture clinically meaningful risk.
Finally, I applaud the investigators’ SPACG construct, which pragmatically recategorizes treated narrow-angle eyes to avoid misclassifying PACG as POAG in settings where LPI and cataract surgery are common; this approach likely yields more accurate disease burden estimates and aligns with real-world care pathways.
In summary, PACG was undiagnosed in most individuals with the disease, highlighting the need for improved case detection. Blindness was relatively uncommon in PACG, a novel finding.
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