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Ulrik Frydkjaer-Olsen, Rasmus Soegaard Hansen, Knud Pedersen, Jose G Cunha-Vaz, Rafael Simó, Tunde Peto, Jakob Grauslund; Retinal Vascular Fractals Correlate With Early Neurodegeneration in Patients With Type 2 Diabetes Mellitus. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1803.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate the correlation between early retinal vascular and neurodegenerative changes in diabetic retinopathy (DR).
Altogether 105 patients with type 2 diabetes mellitus (T2DM) with no or mild DR were examined. Forty nine patients were recruited from the baseline population of the EUROCONDOR study, the rest from the local DR screening. Retinal vascular fractal analysis is a global measurement of the density and complexity of the retinal vascular system. Fractal dimension (Fd) using a disc-centered cropped Optos 200Tx image (Optos plc, Dunfermline, Scotland, UK) were used. In a randomly selected eye of each patient, Fd was calculated using SIVA-Fractal (Singapore University, Singapore), a specialized semi-automatic software. Retinal neurodegeneration was evaluated by Topcon 3D OCT-2000 Spectral Domain OCT (Topcon, Tokyo, Japan) and by a RETI-scan multifocal ERG system (Roland Consult, Brandenburg a.d.Havel, Germany) in ring 1-6. Level of DR was determined by a single trained grader in 7-field fundus photos using the Early Treatment Diabetic Retinopathy Scale (ETDRS). Diabetic neuropathy was defined by the presence of neuropathic symptoms or a current patient diagnosis.
Mean age and duration of T2DM were 62.4 and 11.7 years, respectively; 45.7% were men. Mean Fd was 1.413 (range 1.278-1.509) and ETDRS levels were 10 (42.3%), 20 (34.6%) and 35 (23.1%), respectively.<br /> In univariate models, significant correlations were found between Fd and multifocal ERG implicit time of ring 1 (r= -0.25, p=0.01), and Fd and OCT ganglion cell layer (GCL) thickness (r= 0.20, p=0.04).<br /> In a multivariable linear regression model, Fd showed statistically significant correlation with multifocal ERG implicit time of ring 1 (coefficient -0.0021 pr. ms, p=0.03), GCL (coefficient 0.0013 per µm, p=0.03) and neuropathy (coefficient -0.0200 for neuropathy present versus absent, p=0.04). There were no correlations between Fd and age, sex, duration of diabetes, hypertension, BMI, nephropathy or other OCT and multifocal ERG parameters.
In patients with T2DM and no/mild DR, independent correlations were found between early vascular and neurogenic changes. Decreased retinal vascular fractal dimension and GCL-loss as well as prolonged central implicit time seem to be early events in DR. Thus, retinal fractal analysis might help to identify patients with early neurodegenerative changes.
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