Background:Retinal vessels may provide information on cerebral vascular pathology,because they share many features with cerebral vessels.A smaller ratio of the retinal arteriolar-to-venular diameters reportedly predicts the risk of stroke.It is unclear if this is due to arteriolar narrowing or venular dilation.Objective:To investigate whether smaller arteriolar or larger venular diameters are related to the risk of stroke and cerebral infarction.Methods:This study was based on the prospective population-based Rotterdam Study and included 5,540 participants of 55 years or over,who had gradable fundus transparencies and were free of stroke at baseline(1990 to 1993).For each participant,retinal arteriolar and venular diameters were measured on digitized images of one eye.Follow-up for first-ever stroke was complete until January 1,2002.Results:After a mean follow-up of 8.5 years,411 participants had a stroke,of whom 259 had cerebral infarction.Larger venular diameters were associated with an increased risk of stroke(hazard ratio HR adjusted for age and sex per SD increase:1.12 95% CI:1.02 to 1.24)and cerebral infarction(HR:1.15 95% CI:1.02 to 1.29).Smaller arteriolar diameters were neither related to the risk of stroke(HR per SD decrease:1.02 95% CI:0.93 to 1.13)nor to the risk of cerebral infarction(HR:1.02 95% CI:0.90 to 1.15).After additional adjustment for other cardiovascular risk factors,the results did not change.Conclusions:Larger retinal venular diameters are associated with an increased risk of stroke and cerebral infarction.The role of venules in cerebrovascular disease warrants further exploration. Background: Retinal vessels may provide information on cerebral vascular pathology, because they share many features with cerebral vessels. A smaller ratio of the retinal arteriolar-to-venular diameter reportedly predicts the risk of stroke. It is unclear if this is due to arteriolar narrowing or venular dilation. Objective: To investigate whether smaller arteriolar or larger venular diameters are related to the risk of stroke and cerebral infarction. Methods: This study was based on the prospective population-based Rotterdam Study and included 5,540 participants of 55 years or over, who had gradable fundus transparencies and were free of stroke at baseline (1990 to 1993). For each participant, retinal arteriolar and venular diameters were measured on digitized images of one eye. Fall-up for first-ever stroke was complete until January 1, After a mean follow-up of 8.5 years, 411 participants had a stroke, of whom 259 had cerebral infarction. Larger venular diameters were associated with an increased risk of stroke (hazard ratio HR adjusted for age and sex per SD: 1.12 95% CI: 1.02 to 1.24) and cerebral infarction (HR: 1.15 95% CI: 1.02 to 1.29) .Smaller arteriolar factors were neither related to the risk of stroke (HR per SD decrease: 1.02 95% CI: 0.93 to 1.13) nor to the risk of cerebral infarction (HR: 1.02 95% CI: 0.90 to 1.15) .After additional adjustment for other cardiovascular risk factors, the results did not change. Confc: Larger retinal venular diameters are associated with an increased risk of stroke and cerebral infarction. The role of venules in cerebrovascular disease warrants further exploration.