Diabetic macular edema is the leading cause of central vision loss and even blindness in diabetic retinopathy. Compared to FFA, OCT can obtain the high-resolution 3D image quickly, easily to reflect the details of the tissue and realize the quantitative measurement. As a novel technology, OCT angiography (OCTA) can display microvascular structure from different layers of retina and choroid, having its advantage of quantifying the vessel density and the lesion area. By detecting fundus morphology, quantifying and quantitating the retinal vessels and vessel density, the combination of OCT and OCTA could play a guiding role in diagnosis, classification, treatment and prognosis of diabetic macular edema.
ObjectiveTo observe the changes of blood flow density in the macular area of normal eyes, and to analyze its correlation with age. MethodsA cross-sectional study. Two hundred and fifty normal healthy subjects (125 males and 125 females, aged 44.76±14.77) in routine ophthalmologic examination at the Department of Ophtalmology of Guangdong Provincial People’s Hospital during June 2017 to June 2018 were enrolled. Among them, 20 to 29, 30 to 39, 40 to 49, 50 to 59, and ≥ 60 years old were 50 subjects (50 eyes) in each. BCVA, slit lamp microscope, indirect ophthalmoscope, OCT angiography (OCTA) examinations were conducted for all eyes. The subjects were examined by both eyes, and the data of 1 eye was selected by EXCEL to generate random numbers, including 126 right eyes and 124 left eyes. The range of 6 mm × 6 mm in the macular area was scanned using a frequency domain OCTA instrument. The software automatically divides it into three concentric circles centered on the macular fovea, which were foveal area with a diameter of 1 mm, parafoveal area of 1 to 3 mm, and foveal peripheral area of 3 to 6 mm. The blood flow density of superficial capillary vessel, deep capillary vessel and foveal avascular area (FAZ) within a 300 μm width (FD-300), FAZ area, perimeter (PERIM), non-circularity index, center retinal thickness (CRT) were measured. The relationship between the blood flow density in macula, CRT, FAZ and age was analyzed by Pearson correlation analysis. ResultsThe mean blood flow density of superficial capillary vessel and deep capillary vessel were (51.61±2.54)% and (54.04±5.46)%, respectively. The average FD-300, CRT, PERIM and non-circularity index were (285.55±12.13) μm, (2.150±0.367) mm, 1.10±0.04, respectively. The relevance of the results showed that the age was negatively correlated with the blood flow density of whole area (r=−0.335, −0.279; P＜0.01), parafoveal area (r=−0.255, −0.368; P＜0.01), foveal peripheral area (r=−0.330, −0.269; P＜0.01) in superficial capillary vessel and deep capillary vessel as well as FD-300 (r=−0.311, P＜0.01), but not correlated with the blood flow density of foveal area (r=−0.071, −0.118; P=0.264, 0.064). There was no relationship between the age and the FAZ area, PERIM, non-circularity index (r=−0.070, −0.055, 0.074; P=0.267, 0.385, 0.142). The age was negatively correlated with the average CRT (r=−0.217, P＜0.01), but not correlated with the CRT in foveal area (r=0.115, P=0.068). The CRT was positively correlated with the blood flow density of superficial capillary vessel and deep capillary vessel in foveal area (r=0.715, 0.653; P＜0.01), but negatively correlated with the FAZ area (r=−0.669, P＜0.01). ConclusionThe capillary blood flow density of macular area in the normal eyes decreases with age.