To investigate clinical characteristics, comorbidities, seasonal onset, and antihypertensive medication use among acute primary angle-closure (APAC), chronic primary angle-closure glaucoma (CPACG), and primary angle-closure suspect (PACS) patients.

A retrospective cross-sectional study of 484 Chinese patients was conducted. Baseline demographics, hypertension and diabetes prevalence, antihypertensive medication use, and seasonal onset patterns were compared across primary angle-closure disease (PACD) subtypes. Seasonal variation was assessed using the von Mises distribution, with subgroup analyses stratified by systemic conditions and medication use.

CPACG patients were older (median 71 vs 67y in APAC, P<0.001) with higher hypertension (47.74% vs 31.16%, P=0.003) and diabetes prevalence (20.60% vs 10.05%, P=0.014). Multivariate analysis showed hypertension [odds ratio (OR)=1.85] and diabetes (OR=2.00) were significant predictors of CPACG vs APAC. A modest but significant seasonal peak of APAC onset was identified in early June. Subgroup analyses revealed significant shifts in seasonal patterns according to hypertension (P=0.023), diabetes (P<0.001), and calcium channel blocker (CCB) use (P=0.025). Angiotensin-converting enzyme inhibitors (ACEIs) use was absent in APAC patients but present in CPACG and PACS groups; CCB use was highest in APAC patients, though differences were not statistically significant.

Vascular and metabolic comorbidities are more prevalent in CPACG than APAC, suggesting their role in CPACG pathogenesis. The early-summer peak in disease onset points to possible environmental triggers. Seasonal variation in APAC onset appears to be influenced by systemic vascular conditions and antihypertensive medication use, supporting a multifactorial interaction between environmental, systemic, and pharmacologic factors in APAC.