Objective To observe the morphological changes of macular capillary in type 2 diabetic mellitus (DM) patients without clinical features of diabetic retinopathy (DR) by optical coherence tomography angiography (OCTA). Methods This is a prospective clinical case-control study. Forty-three eyes of 22 patients with DM without clinical features of DR (case group) and 40 control eyes of 20 age- and sex-matched healthy physical examination subjects (control group) were enrolled in this study. All subjects underwent OCTA examination with mode of retinal blood flow imaging, macular 3 mm×3 mm and 6 mm×6 mm area, signal strength ＞45. Foveal avascular zone (FAZ) area, foveal capillary density, parafovea capillary non-perfusion, and micro-aneurysm in shallow capillary vessel layer were evaluated. Results In case group, the mean FAZ area was (0.397±0.141) mm2 and the mean foveal capillary density was (44.6±0.62) %. In control group, the mean FAZ area was (0.253±0.112) mm2 and the mean foveal capillary density was (48.6±0.58) %. FAZ area of eyes in case group was larger than that in control group (t=1.017,P＜0.05). There was no difference of foveal capillary density between two groups (t=1.499,P＞0.05). The spider web-like FAZ and normal foveolar avascular zone were observed in eyes of control group. The parafovea capillary non-perfusion, abnormal foveolar avascular zone, micro-aneurysm and tortuosity of vessels were observed in eyes of case group. Parafovea capillary non-perfusion (χ2=4.542), micro-aneurysms (χ2=5.183) were seen more often in case group than control group (P＜0.05). Conclusion Type 2 DM patients have abnormal retinal vascular microcirculation before DR using OCTA, including larger FAZ area, parafovea capillary non-perfusion, abnormal foveolar avascular zone, micro-aneurysm and tortuosity of vessels.
ObjectiveTo observe the changes of macular vascular density of hypertensive patients without obvious hypertensive retinopathy (HRP).MethodsTwenty-three patients (hypertension group) diagnosed as grade 2 or grade 3 essential hypertension in Cardiology Department of Renmin Hospital of Wuhan University from January to April 2019 were enrolled in the study. Among them, there were 13 males and 10 females. The mean age was 61.6 ± 5.6 years, and the mean BCVA was 0.74 ± 0.16. The course of hypertension was more than 7 years; Keith Wagener (K-W) grade was 0 or 1. Fifteen age-matched people without hypertension were selected as the control group, among which included 8 males and 7 females. Their average age was 59.7 ± 4.4 years and the average BCVA was 0.79 ± 0.17, the K-W grades were 0. There was no significant difference (P=0.265, 1.000, 0.563) between the two groups in age (t=1.739), sex ratio (χ2=0.036) or BCVA (t=0.585). All subjects were examined by BCVA, fundus photography and OCTA. OCTA scanned the macular area in the range of 3 mm × 3 mm. The software automatically divided the image into two concentric circles with the macular fovea as the center, which are the inner ring with a diameter of 1 mm (foveal area) and the outer ring with a diameter of 1-3 mm. The blood flow density of the whole, temporal, upper, nasal and lower capillary layers within 3 mm of the macular area, and foveal avascular zone (FAZ) area, central foveal retinal thickness (CFT) were measured.ResultsSignificant differences were observed in the vascular densities of total, temporal, nasal and inferior area of maculas (t=2.188, 2.472, 5.105, 2.734; P=0.037, 0.020, 0.000, 0.010) between the two groups, while no significant differences were evidenced in foveal vascular densities and superior vascular densities (t=0.575, 0.140; P=0.570, 0.889). There was no significant difference in FAZ area or CFT between the two groups (t=0.367, 0.753; P=0.714, 0.457). Macular arches were intact in all hypertension patients.ConclusionsThe vascular densities of total, temporal, nasal and inferior area of maculas in the hypertension patients without HRP decreased. The area of FAZ did not expand, and the structures of macular arch ring were normal.
Microvascular dysfunction is a key pathological mechanism of diabetic retinopathy (DR). In recent years, it has been found that the phenomenon of "metabolic memory" is prevalent in diabetic patients, and diabetic microangiopaplasia cannot be avoided even if patients’ blood glucose is well controlled. Therefore, it is necessary to explore DR from a genetic perspective. miR-126 is the unique microRNA specifically expressed in vascular endothelial cells, which is closely related to the formation of neovascularization and can affect the stability of DR microvessels as well as the germination and migration of endothelial cells, and its gene level is significantly negatively correlated with the expression of vascular endothelial cell growth factor. The potential value of intracellular and circulating miR-126 in the regulation of DR microvascular homeostasis, early diagnosis and treatment, and monitoring of disease course has attracted great attention. However, studies in this area are mostly hypothesis-driven and still have some limitations. It is believed that with the rapid development of genomics, the miRNA spectrum and its molecular mechanism in eye development and eye diseases will gradually become clear, which may lead to a breakthrough in the intervention of individual refractory retinal diseases and establish a new miRNA diagnosis and treatment method in the future.