Smoking and retinal vein occlusions. The Beijing Eye Study

Abstract

Dear Editor, One of the most common ocular vascular diseases is retinal vein occlusion, the prevalence of which has been estimated to range from 0.3% to 1.6% in recent populationbased studies, such as the Blue Mountains Eye Study [1], the Beaver Dam Eye Study [2], a combined analysis of the Atherosclerosis Risk in Communities and Cardiovascular Health Studies [3], and the Singapore Malay Eye Study [4]. Considering that smoking is generally one of the major risk factors for vascular diseases, we addressed in our study whether smoking is associated with the prevalence of retinal vein occlusions. The Beijing Eye Study is a population-based study, which was first performed in 2001 and included 4,439 subjects (response rate: 83.4%) out of 5,324 subjects invited to participate, with an age of 40+ years. The study was repeated in 2006, with 3,251 subjects participating (response rate: 73.2%). The Medical Ethics Committee of the Beijing Tongren Hospital had approved the study protocol. The study has been described in detail recently [5]. Using fundus photographs (fundus camera: CR6-45NM, Canon Inc., USA), the prevalence of retinal vein occlusions was determined [5]. Recent retinal vein occlusions were characterized by the presence of retinal edema, optic disc hyperemia or edema, scattered superficial or deep hemorrhages, and venous dilatation. Old retinal vein occlusions were characterized by occluded and sheathed retinal veins. Additionally, we measured the systolic and diastolic blood pressure, and body height and body weight. Fasting blood samples were biochemically examined, and information was obtained about smoking habits. Glaucoma was defined by the appearance of the optic nerve head, as described in detail recently [5]. The study sample consisted of 3,214 subjects with a mean age of 55.3±10.0 years (range: 40–84 years) and a mean refractive error of −0.36±2.22 diopters (−20.1 diopters to +7.50 diopters). A retinal vein occlusion was detected in 37 subjects (1.2%). Out of the 3,214 subjects, 1,042 participants (32.4%) were current smokers (n=725; 16.3 % of the study population) or former smokers (n=317; 7.1% of the study population). In univariate analysis, prevalence of retinal vein occlusions was significantly associated with higher age (P<0.001), body mass index (P=0.001), mean arterial blood pressure (P=0.002), presence of glaucomatous optic nerve damage (P<0.001), and former smoking (P=0.002). In univariate analysis, retinal vein occlusions were not significantly associated with smoking as a whole group [P=0.16; odds ratio (OR): 1.60; 95% confidence interval (CI): 0.83, 3.07], nor with current smoking (P=0.43; OR: 0.66; 95% CI: 0.28, 1.59), level of education (P=0.15), gender (P=0.68), urban versus rural region (P=0.77), fasting blood levels of glucose Proprietary interest none