AIM: Using optical coherence tomography angiography(OCTA)to observe the changes and clinical significance of macular blood flow density in patients with diabetic retinopathy(DR).

METHODS: Totally 47 eyes(28 patients)with diabetic retinopathy(DR)were enrolled in the DR group. According to the international clinical grading criteria of diabetic retinopathy, 30 eyes(19 patients)with non-proliferative diabetic retinopathy were classified as the NPDR group, and 17 eyes(11 patients)with proliferative diabetic retinopathy were classified as PDR group. A total of 46(27 subjects)healthy eyes with matched age were enrolled in the control group. All the subjects underwent the 3mm×3mm scanning of macular retina by optical coherence tomography angiography(OCTA), obtaining 4 levels of macular blood flow density map. The macular blood flow density at 3 levels, including superficial retinal layer, deep retinal layer and choroidal capillaries layer, were measured.

RESULTS: The macular blood flow density of superfical retinal layer, deep retinal layer and choroidal capillaries layer in DR group were 0.4963±0.0840, 0.4798±0.0801 and 0.5290±0.0528, respectively. Among them, the blood flow density of each layer were 0.5064±0.0843,0.4983±0.0766,0.5345±0.0529, respectively, for the NPDR group, and were 0.4786±0.0830, 0.4473±0.0778,0.5192±0.0526, respectively, for the PDR group. For the control group, the density of each layers were 0.5919±0.0704, 0.6301±0.0527, 0.5691±0.0169, respectively. The macular blood flow density was significantly different in the superficial retinal layer, deep retinal layer and choroidal capillary layer between the control group and the NPDR group, as well as the PDR group and the DR group(total P<0.001). Statistically significant difference was found between the NPDR group and the PDR group in the deep retina layer(P=0.029), but not in the superficial retina layer and choroid capillary layer(P=0.236, 0.268).

CONCLUSION: Compared with the control group, the macular blood flow density of superficial retinal layer, deep retinal layer and choroidal capillary layer in the patients with diabetic retinopathy decreased significantly. It indicated that the macular ischemia existed in both retina and choroid. By quantitatively measurement of the macular blood flow, OCTA may be used for monitoring the progression of diabetes, and early detection of diabetic retinopathy.