ObjectivesAcute angle-closure glaucoma (AACG) is a major cause of irreversible and severe visual function loss. Robust rise in AACG was observed in the ophthalmic outpatient clinics concomitant with the outbreak of COVID-19 infection in China after the relaxing of “zero-COVID policy” in early December 2022. Here we compared the demographic and clinical profiles of patients with AACG before, during and after the COVID-19 outbreak. Underlying mechanisms were tentatively investigated. MethodsThis is a retrospective comparative study. Consecutive cases with newly diagnosed AACGs in a tertiary eye hospital were retrospectively collected during December 17, 2022 to January 8, 2023. Data from the same period in 2018-2019 and 2019-2020, 2020-2021 and 2021-2022, and 2023-2024 were collected as pre-pandemic, pandemic-control, and post-pandemic control, respectively. For the patients in 2022-2023 outbreak group, COVID-19 infection was confirmed by reversed transcriptase-polymerase chain reaction or antibody test for severe acute respiratory syndrome coronavirus disease 2 (SARS-CoV-2) from nasopharyngeal swabs. Ocular parameters, serum electrolytes and coagulative parameters were compared between COVID-19 positive and negative AACGs in observational group. SARS-CoV-2 nucleic acid in the aqueous humor was detected. ResultsA total of 106 AACG cases were diagnosed during the outbreak period in 2022-2023. In contrast,18 (in 2018-2019) and 22 (in 2019-2020) cases were included during pre-pandemic period, and 21 (in 2023-2024) during the post-pandemic period. Only 13 and 4 newly onset AACG were included in 2020-2021 and 2021-2022 during the pandemic-control period, respectively. Younger age and higher proportion of bilateral involvement were detected in COVID-19 outbreak group than that of other groups (p=0.034 and p=0.080). Sixty-eight (64.2%) patients in the outbreak group had a confirmed COVID-19 infection. Intervals between infection and AACG attack was 52±85h (0-15d). Fifty-three patients (77.9%) reported the applications of ibuprofen or other antipyretic medications and 25 (36.8%) reported large volume water intake before AACG attack. COVID-19-positive AACG patients had higher level of D-dimer than their negative counterparts (1.13±2.60mg/L vs. 0.46±0.43mg/L, p=0.083). No difference in IOP, serum electrolytes, and coagulative parameters was observed between COVID-19 positive and negative cases. SARS-CoV-2 were negative in the aqueous humor from 14 COVID-19 positive and 8 negative patients. ConclusionCOVID-19 infection surged the onset of AACG in patients at risk. Mental stress, water intake, increased choroidal thickness due to SARS-CoV-2 induced ACE receptor activation, and hyper-coagulation, may contribute to the disease onset. Ocular involvement should not be ignored in both routine and new systemic emergent conditions.