Abstract
Purpose: :
To assess retinal vessel calibre associations with diabetes, glycaemia and retinopathy status in an older population.
Methods: :
The Blue Mountains Eye Study examined 3654 Australian residents aged 49 years or older in two postcode regions in 1992–4. Retinal vessel diameters were measured from digitised images in 3368 participants and summarised as central retinal venular and arteriolar equivalents. Diabetes was defined on self–report, or fasting blood glucose ≥ 7.0 mmol/L. Impaired fasting glucose was defined as fasting blood glucose greater than 6.0 but less than 7.0 mmol/L. Diabetic retinopathy was graded from retinal photographs using the modified Airlie House system.
Results: :
After adjusting for other factors, venular calibre was significantly larger among participants with moderate–severe nonproliferative diabetic retinopathy (NPDR) as compared to milder retinopathy levels, diabetic patients without retinopathy, and non–diabetic controls (mean 263 µm for severe NPDR, 237 µm for moderate NPDR vs 221 µm for mild NPDR, 223 µm for no retinopathy and 222 µm for normal controls, p<0.0001 for severe NPDR and p=0.009 for moderate NPDR). Each 1 standard deviation (20 µm) increase in venular diameter was associated with a 2–4 fold greater chance of having moderate–severe NPDR compared to persons without diabetes, especially among participants with concomitant hypertension. Venular diameter was not otherwise significantly associated with duration of diabetes, degree of glycemia or impaired fasting glucose. Mean arteriolar calibre was significantly larger in participants with diabetes for less than 10 years as compared to non–diabetic controls, after adjusting for other factors (196 µm vs 190 µm, p=0.002; 192 µm for diabetes >10years), and among participants with mild to moderate–severe NPDR (201 µm for moderate–severe NPDR and 197 µm for mild NPDR vs 192 µm for no retinopathy and 190 µm for normal controls; p<0.05 for moderate–severe and for mild NPDR). Arteriolar calibre was not otherwise associated with degree of glycaemia or impaired fasting glucose.
Conclusions: :
Wider venular calibre was associated with more severe retinopathy in older persons with diabetes, consistent with earlier findings in younger diabetic populations. An association between arteriolar widening and diabetes of relatively short duration, and with retinopathy, was also found.
Keywords: clinical (human) or epidemiologic studies: risk factor assessment • diabetes • retina