LAUSR

PURPOSE To investigate seasonal variation in optic disc hemorrhage (DH) by review of fundus photographs representative of the past two calendar years (2019 and 2020). DESIGN Retrospective, observational trend study. METHODS Patients who had visited the Glaucoma Clinic of Seoul National University Hospital and underwent fundus photography were included. All of the available stereo disc photography (SDP) and red-free retinal nerve fiber layer photography (RNFLP) taken between January 1st, 2019 and December 31st, 2020 was retrospectively reviewed. The monthly incidence rate of DH was determined by reference to the photography. Seasonal temperature information and patients' intraocular pressure (IOP) information were obtained, organized and analyzed. RESULTS Fundus images of 13,514 eyes were reviewed, and 454 eyes were confirmed to have DH. Poisson regression analyses revealed that as the temperature rose by 1°C, the DH risk ratio was reduced to 0.979 (95% CI 0.969-0.989, p<0.01). The DH incidence ratio was 1.53 (95% CI 1.23-1.91, p<0.01) for the T<10°C group relative to the T≥20°C group. The IOP of the patients with DH in winter was significantly higher than that measured in summer. CONCLUSION DH is affected by temperature, and as such, shows seasonal variability. This variability is believed to be caused by temperature-related factors such as IOP or hematological factors.