Background: Retinal capillary is vulnerable to diabetes, whether gestational diabetes mellitus (GDM) eyes without clinical retinopathy have capillary abnormalities has not been well studied. To observe the microvasculature changes in eyes of GDM women compared with normoglycemic pregnant women and non-pregnant women by optical coherence tomography-angiography (OCT-A). Methods: GDM women, age-matched normoglycemic pregnant women and non-pregnant women were included in this study. All subjects were examined by OCT-A, vascular density and macular foveal parameters were measured automatically. Results: Thirty eight non-pregnant women (NC group), thirty pregnant women without GDM (PC group), and thirty one GDM women (GDM group) were included in this study. There was a significant reduction of vascular density in superficial capillary layer, but an increase in deep capillary layer in PC and GDM groups (P < 0.001). When in terms of the average vascular density, the difference was insignificant among these three groups. Although all the measurements were similar between PC and GDM groups, more capillary “dropout” changes were detected in GDM group. Unexpectedly, the abnormal changes of central macular thickness thinning and foveal avascular zone enlargement seen during pregnancy were improved when compared to PC group. Conclusions: The changes of vascular density implied the redistribution of capillary network from superficial to deep layer under pregnancy and GDM states. Although the transient hyperglycemia aggravates the changes of capillary “dropout”, GDM group revealed the improvement of central macular thickness thinning and foveal avascular zone enlargement during pregnancy.

Purpose: This study aimed to investigate the effects of O-linked N-acetylglucosamine modification (O-GlcNAcylation) on connexin43 (Cx43) expression and its subsequent effects on tight junction properties in diabetic retinopathy (DR). Methods: O-GlcNAcylation levels in primary human retinal vascular endothelial cells (HRVECs) and retinas from rats with diabetes were regulated by treatment with Thiamet G or alloxan. Immunoprecipitation was used to examine the relationship between O-GlcNAcylation and Cx43 expression. Stable overexpression and knockdown of Cx43 in HRVECs were achieved using lentivirus constructs; further, their effects on occludin and zonula occluden-1 (ZO-1) expression and tight junction barrier function were determined. Results: O-GlcNAcylation level increased significantly, whereas Cx43 expression decreased in retinas from rats with diabetes and HRVECs cultured under high-glucose conditions. Immunoprecipitation revealed that Cx43 was modified by O-GlcNAcylation and phosphorylation simultaneously. O-GlcNAcylation inhibition negatively regulated both total Cx43 and phosphorylated Cx43 expression, subsequently disrupting tight junction properties. Conversely, Cx43 overexpression reversed the disruption of tight junction properties and downregulated vascular endothelial growth factor expression. Consistently, Cx43 overexpression increased transendothelial electrical resistance values in HRVEC layers. Conclusions: O-GlcNAcylation negatively regulated Cx43 expression, contributing to the disruption of the blood retinal barrier. However, O-GlcNAcylation inhibition and Cx43 overexpression could reverse the tight junction disruption. Therefore, O-GlcNAcylation inhibition is a potential target for avoiding tight junction disruption through the Cx43 pathway in DR.

Purpose: To study seasonal and monthly variation in Central Serous Chorioretinopathy (CSC) and its possible association with choroidal thickness among Chinese population.