To investigate Omicron's impact on clinical presentation of acute primary angle closure (APAC) in China. A consecutive case series with historical controls was conducted at Shenzhen Eye Hospital, the largest specialized hospital in Shenzhen, China. Medical records from a two-month period during the Omicron pandemic (December 1, 2022, to January 31, 2023) were compared with records from two control groups (12/2018-1/2019 and 12/2021-1/2022) before pandemic. Patients with APAC were included, and the prevalence of APAC and demographic characteristics in Omicron-infected and non-infected patients were compared. Seventy-one (23.43%) out of 303 patients were diagnosed with APAC in the pandemic cohort, which was 2.98 and 2.61 times higher than that in control cohorts (7.87% in 2019, 8.96% in 2022, P<0.001). The pandemic cohort has significantly higher Omicron-infected rate (78.87% vs 0 vs 0; P<0.001), lower proportion of glaucoma history (16.90% vs 42.86% vs 41.67%, P=0.005), higher surgical rate (95.77% vs 83.33% vs 78.57%, P=0.024), higher total medical costs and larger pupil diameter (5.63±0.15 vs 4.68±0.15 vs 4.69±0.22 mm, P<0.01). In 83% Omicron-infected patients, ocular symptoms appeared within 3d after systemic symptoms onset. In multivariate analysis, Omicron infection (P<0.001) was the only independent predictor of pupil diameter. In the Omicron epidemic in China, there is an increase of prevalence and severity of APAC, particularly focusing on the first 3d following infection.