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 ± 2.60 mg/L vs. 0.46 ± 0.43 mg/L, p = 0.083). No difference in IOP, serum electrolytes, and coagulative parameters other than D-dimer 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.