AIM: Meta-analysis was performed to systematically evaluate the macular vessel density(VD)and foveal avascular zone(FAZ)areas in patients with no diabetic retinopathy(NDR)by using optical coherence tomography angiography(OCTA). This study aimed to investigate the microcirculatory characteristics of the retina in the early stage of diabetes.

METHODS: PubMed, Embase, Web of Science and Cochrane Library databases were searched for publications from 1 January, 2011 to 5 January, 2021 on OCTA analysis of VD in different regions of the macular area in diabetic patients with NDR. Compare the differences in the superficial parafoveal VD(spafVD), superficial perifoveal VD(spefVD), deep parafoveal VD(dpafVD), deep perifoveal vessel density(dpefVD), superficial FAZ area and best corrected visual acuity(BCVA)between NDR group and the normal control group(healthy population matched for the age at the same time and gender with patients in the NDR group).

RESULTS: Thirteen publications with a total of 1 227 eyes(558 eyes in normal control group and 669 eyes in NDR group)were included in the study. Meta-analysis showed that compared with the control group, NDR group displayed a significant decrease in spafVD(MD=-1.90, 95%CI: -2.43--1.37, P<0.00001), spefVD(MD=-1.29, 95%CI: -2.14--0.44, P=0.003), dpafVD(MD=-2.18, 95%CI: -2.69--1.67, P<0.00001)and dpefVD(MD=-2.37, 95%CI: -3.27--1.46, P<0.00001), with a more significant reduction in dpefVD, and superficial FAZ area(MD=0.04, 95%CI: 0.03-0.06, P<0.00001)was increased. There was no difference in BCVA(MD=0.00, 95%CI: -0.01-0.02, P=0.44)between the two groups.

CONCLUSION:Capillary injury in the deep perifoveal region of the macular area is the earliest manifestation of retinal microcirculation disturbance in diabetic patients, and is also a key indicator for clinical follow-up of diabetic retinopathy.