Influence of Smoking and Controlled Medical Conditions on the Risks of Branch Retinal Vein Occlusion in South Korea: A Population-Based Study

Purpose: To evaluate the effect of controlled medical conditions and risk of lifetime smoking history on the prevalence of branch retinal vein occlusion (BRVO) based on the Korea National Health and Nutrition Survey (KNHANES) database from 2017–2021. Methods: The study population consisted of individuals aged ≥ 40 years who had completed ophthalmological questionnaires, underwent comprehensive ophthalmological examinations, and had at least one good-quality readable fundus photograph. Age, sex, hypertension status, diabetes status, dyslipidemia status, body mass index status, a history of chronic kidney disease (CKD), a lifetime smoking history of ≥ 100 cigarettes, and glaucoma were subjected to univariate and multivariate logistic regression analyses. Results: The estimated prevalence (± standard error) of RVO was 0.5% (±0.1%). Significant risk factors were one-year increase in age, female sex, hypertension (stage 1, controlled, uncontrolled, and undiagnosed hypertension), underweight, pre-obesity, history of CKD, lifetime smoking history of ≥ 100 cigarettes, and glaucoma. Controlled diabetes decreased the risk of BRVO by 55% (odds ratio [OR] = 0.45, 95% confidence interval [CI] = 0.22–0.89, p = 0.022) and controlled hyper-high-density-lipoprotein (HDL)-cholesterolemia decreased the risk by 69% (OR = 0.31, 95% CI = 0.13–0.76, p = 0.010). Conclusion: This study, for the first time, reported the association between lifetime smoking history of ≥ 100 cigarettes and BRVO in Korea. The risk of BRVO was lower in participants with controlled diabetes and hypo-HDL-cholesterolemia.