Seasonal variation in the occurrence of retinal vein occlusion: a 4-year cross-sectional study

Background Retinal vein occlusion (RVO) is a common retinal vascular disease that causes a loss of vision. Therefore, we investigated whether there is seasonal variation in the onset of RVO, to examine the possibility of preventing it. Methods Patients with RVO who were treated at the Juntendo University Urayasu Hospital between April 2013 and March 2017 were included in this retrospective study. The season in which the RVO occurred was recorded for each case, and the cases were grouped into six 2-month periods based on the month of RVO, and classified by age, sex and hypertension status. The frequency of occurrence of RVO across seasons was compared using a chi-squared test. Results A total of 348 patients with RVO presented during the study period, with information regarding the date of RVO onset. The cohort of 348 consisted of 167 males and 181 females who, overall, had a mean age of 64.0 years (range 17–96 years). The highest incidence of RVO onset was during January/February, with the lowest incidence during July/August. Patient age, sex and hypertension status did not influence the results. Conclusions The seasonal onset of RVO tended to be higher in January/February and May/June, and lower in July/August. These findings suggest that eyecare professionals should be more vigilant in watching for the occurrence of RVO during winter and the rainy season, regardless of the patient’s sex, age or hypertension status.