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Georgios Leontidis, Francesco Caliva, Bashir Al-Diri, Andrew Hunter; Study of the retinal vascular changes between the early stages of diabetes and first year of diabetic retinopathy. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):2015.
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© ARVO (1962-2015); The Authors (2016-present)
Controversy exists on how the functional impairment due to diabetes affects the retinal vasculature, leading to diabetic retinopathy(DR), which still remains a main cause of blindness. We investigated the hypothesis that there are significant vascular changes that occur during the progress of diabetes, until the first lesions appear in the retina.
Forty fundus images, from a UK database of diabetes screening, of the right eye from twenty progressed patients (one from the early stages of diabetes and one from the first year of DR per patient) with no other diseases were used. Measurements of widths (in pixels) and angles (in degrees) were taken from eight vessel junctions per image (four veins and four arteries), using a semi-automatic tool. In total N0=960 widths (480 for pre-DR and 480 for post-DR for both arteries and veins) and N1=320 angles (similarly) were measured and analysed using a novel approach of a hybrid Anova model, based on a nested and factorial design. All the junctions between the two images of the same patient were exactly matched in order to investigate the targeted changes in the same vessel during the progress of diabetes. In this way of controlled analysis, we minimise the error that we would be having by using random junctions in every image.
Significant results were found for all the combinations apart from veins angles. Compared to pre-DR, the post-DR veins and arteries widths show on average a decrease by 9.25% (F(1,239)=25.11, p=1.05e-06) and 6.89%(F(1,239)=9.77, p=0.002) respectively. Regarding the angles, the post-DR angles of the arteries were decreased by 3.25% (F(1,79)=4.83, p=0.029), whereas the veins had a non-significant decrease by 0.2% (F(1,79)=0.03, p=0.873). The overall group means of the veins and arteries widths for pre/post-DR were 13.08 (±4.1)/11.87(±3.9) and 10.74(±3.8)/10.01(±3.5) respectively. On the other side, for pre/post-DR veins and arteries angles, the group means were 81.40(±10.7)/81.23(±10.51) and 88.9(±13.1)/86.08(±12.01) respectively.
Diabetes, through the hyperglycaemia that it causes, affects the retinal blood flow and the vessel wall structure. As a consequence the whole vascular geometry gets affected, targeting both arteries and veins. Analysing comprehensively the vasculature and adding risk factors can give us reliable predictors of DR.
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