This study investigated the presence of hyper reflective foci (HRF) in asymptomatic patients affected by type 1 or type 2 diabetes, separately, without clinically significant diabetic macular oedema and visual impairment. In total 71 eyes with non-proliferative diabetic retinopathy were imaged using SD OCT. Thirty-three eyes were from type 1 diabetics and 38 eyes from type 2 diabetics. The presence of HRF was defined as the presence of small focal hyper reflective areas scattered mainly in outer retinal layers but also spreading in all retinal layers observed in at least one SD OCT scan. Exclusion criteria included visual impairment, hard exudates or retinal haemorrhages in the fovea, previous retinal surgery / laser, high refractive error, evidence of macular oedema and signs of any other active retinal disease. Control groups of 15 young subjects and 13 older subjects were included for type 1 and 2 diabetics respectively. On SD OCT examination, intraretinal HRF were present in all patients affected by type 1 and type 2 diabetes as scattered punctiform dots invisible at clinical examination, fundus photography and in red free images. HRF amount was significantly higher in the diabetic patients compared to control groups. Type 1 diabetic patients had significantly less HRF than individuals affected by type 2 diabetes. They found patients with a poor quality glycometabolic control were associated with a larger presence of HRF. In the type 2 diabetic group, there was a significant correlation between HRF amount and the presence of hypertension. Sex, patient age and duration of the disease did not influence significantly the number of HRF within the retinal layers. The authors highlight other studies that reported the presence of HRF in the outer retina layers decreases visual acuity of subjects with diabetic macular oedema. Two theories are suggested as to the relevance of HRF; (1) a morphologic sign of accumulation of intraretinal fluid and lipid extravasation, and consequently precursors of hard exudates, and (2) an accumulation of inflammatory cells. The authors conclude by suggesting HFR may be a useful marker for the diagnosis of diabetic retinopathy in the early stage of the disease and an additional marker for the glycometabolic status of the patients.
Optical coherence tomographic hyper reflective foci in early stages of diabetic retinopathy.
De Benedetto U, Sacconi R, Pierro L, et al.