Association Between Baseline Smoking Exposure and Incident Branch Retinal Vein Occlusion: A Retrospective Cohort Study.

PURPOSE: Beyond conventional vascular risk factors, we investigated whether baseline smoking exposure - a modifiable behavioral risk factor - is longitudinally associated with incident branch retinal vein occlusion (BRVO).

METHODS

We analyzed 40,513 individuals (aged ≥40 years) undergoing serial health screenings (2011-2022). Incident BRVO was defined as new retinal hemorrhages in previously normal fundi, confirmed by masked specialists. Hypertension, diabetes, dyslipidemia, and decreased kidney function were defined by conventional criteria. Overweight/obesity was defined as BMI ≥ 23 kg/m2 or waist circumference ≥ 90 cm (men)/≥85 cm (women), and fatty liver by radiologist-confirmed ultrasonography. Smoking was classified as ever versus never. Variables with a log-rank p < 0.20 were entered into a multivariable Cox proportional hazards model.

RESULTS

During a median follow-up of 5.2 years, 58 participants developed BRVO (0.14% of the cohort; 10-year Kaplan-Meier cumulative incidence, 0.30%). In multivariable analysis, age (HR, 1.05; 95% CI, 1.01-1.09), hypertension (HR, 2.27; 95% CI, 1.30-3.96), overweight/obesity (HR, 2.83; 95% CI, 1.39-5.75), and ever smoking (HR, 2.63; 95% CI, 1.20-5.79) were independently associated with incident BRVO.

CONCLUSION

In this longitudinal health-screening cohort, baseline ever smoking was independently associated with incident BRVO after adjustment for conventional vascular risk factors. These findings suggest that smoking, a modifiable exposure, may contribute to BRVO risk beyond established determinants, although the small number of events warrants cautious interpretation and confirmation in larger, multicenter studies.