Does Refractive Error Influence the Association of Blood Pressure and Retinal Vessel Diameters? The Blue Mountains Eye Study

Abstract

Abstract: : Purpose: To determine if refractive errors influence the association of blood pressure and retinal vessel diameters in a population–based, cross–sectional study Methods: Retinal photographs from right eyes of participants (n=3654, aged 49+ years) in the Blue Mountains Eye study taken during baseline examinations (1992–1994) were digitized. The diameter of all retinal vessels located half to one disc diameters from the disc margin was measured using a computer–assisted imaging program. These measurements were combined to provide the average diameters of retinal arterioles and venules of that eye, and the ratio of their diameters, the arteriole–to–venule ratio (AVR). The association of blood pressure and retinal vessel diameters was analyzed before and after correction for refraction using Bengtsson’s formula, that incorporates spherical equivalent refraction. Results: Before refractive correction, each 10mmHg increase in mean arterial blood pressure was associated with a 3.7µm (95% confidence intervals [CI], 3.2 – 4.3) decrease in arteriolar diameter and a 0.9µm (95% CI, 0.3 – 0.9) decrease in venular diameter. After correction for refraction, each 10mmHg increase in mean arterial blood pressure was associated with a 3.7µm (95% CI, 3.2 – 4.2) decrease in arteriolar diameter and a 0.8µm (95% CI, 0.3 – 0.9) decrease in venular diameter. Conclusions: Refraction had no appreciable effect on the association of blood pressure and retinal vessel diameters. These data suggest that an assessment of refraction is not critical to the quantification of generalized retinal arteriolar narrowing associated with hypertension.

Keywords: clinical (human) or epidemiologic studies: risk factor assessment • imaging/image analysis: clinical