Association of Open-Angle Glaucoma With Vascular Risk Factors: The Alienor Study

Abstract

Purpose: : Epidemiological associations of open-angle glaucoma (OAG) with vascular risk factors (smoking, diabetes, obesity, hypercholesterolemia, hypertension) have been inconsistent. The present study reports such associations in French elderly subjects.

Methods: : The Alienor Study is a population-based epidemiological study on nutrition and age-related eye diseases. 963 subjects, aged 73 years or more, had an eye examination in 2006-2008 in Bordeaux (France). Glaucoma was classified according to the criteria of the ISGEO group. Vertical Cup:disc ratio (VCDR) and neuroretinal rim width:disc ratio (RDR) were measured from non-mydriatic digital colour photographs centred on the optic disc. Subjects were considered as affected by glaucoma when they combined structural (VCDR >=0.7 and/or asymmetry of VCDR >=0.2 and/or RDR<=0.1) and functional (visual field with a group of three non borderline points with p<0.01 of which at least one with p<0.005) evidence. We also classified five cases which did not completely meet these criteria (category 2 and 3 diagnosis of ISGEO). All cases of glaucoma were open angle. Vascular risk factors were documented from medical history and clinical examinations (anthropometry, blood pressure, plasma lipids) over the 7 years preceding the eye examination.

Results: : OAG was diagnosed in 45 of 936 subjects with interpretable photographs (4.8 %). After adjustment for age and gender, OAG was not significantly associated with smoking (OR=1.7, 95 % confidence interval (CI) : 0.86-3.52, p=0.12), diabetes (OR=1.3, 95 % CI: 0.86-2.07, p=0.20), body mass index (OR=0.98 for 1 kg/m² increase, 95 % CI: 0.91-1.06, p=0.65), hypercholesterolemia (OR=1.20, 95 % CI: 0.64-2.27, p=0.57). By contrast, it was inversely associated with diastolic blood pressure (average of 4 measurements over the 7 preceding years: OR= 0.66 for a 10-mmHg increase, 95 % CI: 0.45-0.96, p= 0.03), but not with systolic blood pressure (OR=0.90, 95 % CI: 0.75 - 1.08, p=0.27).

Conclusions: : The present study does not evidence a major contribution of vascular risk factors to open-angle glaucoma. By contrast, OAG risk was increased in subjects with low diastolic blood pressure. This observation lends further support to the role of low ocular perfusion in the aetiology of OAG. Low statistical power may explain some of the lack of associations, in particular with smoking and diabetes.

Keywords: clinical (human) or epidemiologic studies: risk factor assessment • optic nerve