Seasonal variation in the incidence of vitreous hemorrhage in proliferative diabetic retinopathy.

PURPOSE: To investigate whether seasonal alterations and meteorological factors are associated with the incidence of vitreous hemorrhage in patients with proliferative diabetic retinopathy (PDR).

MATERIALS AND

METHODS

This retrospective observational study included patients with PDR who visited Seoul St. Mary's Hospital between January 2019 and December 2021. Among the 4,402 eyes with PDR, the presence of vitreous hemorrhage was determined. The monthly incidence of vitreous hemorrhage and meteorological data were obtained and analyzed.

RESULTS

Among 4,402 eyes of PDR, vitreous hemorrhage was observed in 293 eyes (6.66%). The incidence of vitreous hemorrhage was high in May (9.37%, 31 of 331 eyes) and June (8.58%, 26 of 303 eyes). Poisson regression analyses revealed that temperature, humidity, and precipitation-per-hour did not influence the risk of vitreous hemorrhage. Thus, the observed seasonal variation in vitreous hemorrhage was not fully explained by the measured meteorological factors. The Wilcoxon signed-rank test revealed a significant difference between the intraocular pressure (IOP) at the time of hemorrhage (hemorrhage-IOP; hot season) and IOP at the visit immediately before the occurrence of hemorrhage (pre-IOP; cold season) groups (P = .029) and between the hemorrhage-IOP (warm season) and pre-IOP (cold season) groups (P = .041).

CONCLUSION

Vitreous hemorrhage in PDR showed seasonal variations, peaking in May and June. This pattern could not be fully explained by the meteorological variables evaluated; IOP-fluctuations caused by temperature changes and systemic factors such as seasonal changes in glycemic control may contribute to this variability. Further studies are warranted to elucidate the underlying mechanisms.