Objective: Hypertension is closely related to microvascular abnormalities and there is increasing interest in agents that target the microvasculature. The effect of aspirin on the microvasculature has not been well studied. We examined the cross-sectional and longitudinal associations between regular aspirin use and retinal microvascular signs.
Design and methods: We digitized retinal photographs from participants of the Blue Mountains Eye Study cohort (1992-1994, n = 3654, aged over 49 years, and 1997-1999, n = 2335) and used a computer-assisted method to measure average retinal arteriolar and venular diameters. Information on the frequency of aspirin use was collected, with regular aspirin use defined as weekly or daily.
Results: Regular aspirin users comprised 21.2% (n = 775) of the baseline population. At baseline and in individuals who were on one or more antihypertensive medication, regular aspirin use was found to be associated with retinal arterioles on average 3.6 mum (95% confidence interval 1.0, 6.2) wider than those of non-users or occasional aspirin users, after adjusting for age, blood pressure, smoking, diabetes, non-steroidal anti-inflammatory drug use and other variables. Increasing frequency of aspirin use was associated with increasing retinal arteriolar diameter (Ptrend < 0.01). At 5-year follow-up, regular users of aspirin and antihypertensive medication(s) had wider retinal arterioles than those who used aspirin less regularly. Neither antihypertensive medication use alone nor aspirin use alone was associated with wider retinal vessels.
Conclusion: Our finding of a possible association between the combined use of aspirin and antihypertensive agent(s) and wider retinal arteriolar diameter warrants further investigation into the effects of aspirin on the microvasculature.