Estrogen replacement therapy and retinal vascular caliber.

OBJECTIVE: It is unclear if estrogen replacement therapy (ERT) has an effect on the retinal circulation. In the current study, we examine the association of ERT, female reproductive factors, and retinal vascular caliber.
DESIGN: Population-based cross-sectional study. PARTICIPANTS: Women participants aged 43 to 84 years living in Beaver Dam, Wisconsin.
METHODS: Retinal photographs of participants taken at the baseline examination were digitized, and the diameters of arterioles and venules were measured using a well-established technique. Estrogen replacement therapy and female reproductive factors were ascertained by interview. MAIN OUTCOME MEASURES: Retinal arteriolar and venular diameters.
RESULTS: Of the 2469 women participants with data for analysis, 10.5% were current users of ERT and 7.4% were past users. After adjusting for age, blood pressure (BP), body mass index, smoking, and other factors, women who were current users of ERT had narrower retinal arteriolar and venular diameters than those who were past users or never used, with mean arteriolar diameters of 167.6 microm for current users, 170.8 microm for past users, and 170.9 microm for those who never used (P = 0.009) and mean venular diameters of 239.9 microm for current users, 244.0 microm for past users, and 243.9 microm for those who never used (P = 0.02). There was a significant trend of increasing narrowing for both arterioles (P trend, 0.01) and venules (P trend, 0.007) with increasing duration of ERT. Associations were somewhat stronger in younger women and women without a history of hypertension and cigarette smoking. Female reproductive factors (e.g., age of menarche and pregnancy) were not associated with retinal vessel diameters.
CONCLUSIONS: Estrogen replacement therapy is associated with narrower retinal vessel diameters, independent of BP and other vascular factors.