FLOW AND GEOMETRICAL ALTERATIONS IN RETINAL MICROVASCULATURE CORRELATED WITH THE OCCURRENCE OF DIABETIC RETINOPATHY: Evidence from a Longitudinal Study.

PURPOSE: To assess the relationship between flow and geometric parameters in optical coherence tomography angiography images and the risk of incident diabetic retinopathy (DR). METHODS: This prospective, observational cohort study recruited patients with Type 2 diabetes without DR in Guangzhou, China, and followed up annually. A commercially available optical coherence tomography angiography device (DRI OCT Triton; Topcon Inc, Tokyo, Japan) was used to obtain a variety of flow (foveal avascular zone area, vessel density, and vessel length density) and geometric (fractal dimension and blood vessel tortuosity) parameters in superficial capillary plexus (SCP) and deep capillary plexus. The odds ratio (OR) and its 95% confidence interval (CI) were calculated per 1-SD increase in each optical coherence tomography angiography parameter. RESULTS: Over a follow-up of 1 year, 182 of 1,698 participants (10.7%) developed incident DR. After adjusting for conventional risk factors and image quality score, the higher risk of DR onset was significantly associated with the reduced parafoveal vessel density of SCP (OR = 0.81; 95% CI: 0.69, 0.96; P = 0.016), reduced parafoveal vessel length density of SCP (OR = 0.73; 95% CI: 0.59, 0.90; P = 0.003), reduced fractal dimension of SCP (OR = 0.73; 95% CI: 0.61, 0.87; P < 0.001), increased blood vessel tortuosity of SCP (OR = 1.39; 95% CI: 1.18, 1.64; P < 0.001), and increased blood vessel tortuosity of deep capillary plexus (OR = 1.19; 95% CI: 1.01, 1.40; P = 0.033). CONCLUSION: Reduced vessel density and impaired vessel geometry posed higher susceptibility for DR onset in patients with Type 2 diabetes, supporting the adoption of optical coherence tomography angiography parameters as early monitoring indicators of the newly incident DR.

Glycyrrhizin protects against sodium iodate-induced RPE and retinal injury though activation of AKT and Nrf2/HO-1 pathway.

Glycyrrhizin is a bioactive triterpenoid saponin extracted from a traditional Chinese medicinal herb, glycyrrhiza, and has been reported to protect the organs such as liver and heart from injuries. However, there is no report about the effects of glycyrrhizin on atrophic age-related macular degeneration (AMD). This study investigated the effects of glycyrrhizin on retinal pigment epithelium (RPE) in vitro and retina of mice in vivo treated with sodium iodate (SI). Glycyrrhizin significantly inhibited SI-induced reactive oxygen species (ROS), and decreased apoptosis of RPE in vitro. The underlying mechanisms included increased phosphorylation of Akt, and increased expression of nuclear factor erythroid 2-related factor2 (Nrf-2) and HO-1, thereby protecting RPE from SI-induced ROS and apoptosis. Furthermore, glycyrrhizin significantly decreased the apoptosis of retinal cells in vivo, resulting in the inhibition of thinning of retina, decreasing the number of drusen and improving the function of retina. These findings suggested that glycyrrhizin may be a potential candidate for the treatment of atrophic AMD in clinical practice.

The relationship between renal function and diabetic retinopathy in patients with type 2 diabetes: A three-year prospective study.

Objective: To explore the association of diabetic retinopathy (DR) and diabetic macular edema (DME) with renal function in patients with type 2 diabetes mellitus (T2DM). Design: A prospective cohort study. Methods: This single-centre study included patients with no DR, mild non-proliferative DR (NPDR), and no DME at baseline. DR and DME were assessed using 7-field fundus photography and swept-source OCT (SS-OCT). The baseline renal function assessed included the estimated glomerular filtration rate (eGFR) and microalbuminuria (MAU). Cox regression analyses were used to assess the hazard ratio (HR) of renal function with the progression of DR and the development of DME. Results: A total of 1409 patients with T2DM (1409 eyes) were included. During 3 years of follow-up,143 patients had DR progression, and 54 patients developed DME. Low eGFR levels at baseline were associated with the development of DR (HR, 1.044 per 1-SD decrease; 95% CI, 1.035-1.053; P < 0.001). Compared to the participants with eGFRs >90 mL/min/1.73 m2, the participants with eGFRs of 60-90 mL/min/1.73 m2 (HR, 1.649; 95% CI, 1.094-2.485; P = 0.017) or < 60 mL/min/1.73 m2 (HR, 2.106; 95% CI, 1.039-4.269; P = 0.039) had a higher risk of DR progression. Increasing MAU tertiles were associated with progression of DR (Tertile 2: HR, 2.577; 95% CI, 1.561-4.256; P < 0.001; Tertile 3: HR, 3.135; 95% CI, 1.892-5.194; P < 0.001). No significant relationship was found between renal function and the development of DME (P > 0.05). Conclusions: Abnormal renal profiles (i.e., low levels of eGFR and high levels of MAU) were associated with the progression of DR, but not with the development of DME.

Macular Choroidal Thickness and the Risk of Referable Diabetic Retinopathy in Type 2 Diabetes: A 2-Year Longitudinal Study.

Purpose: The purpose of this study was to evaluate the associations between choroidal thickness (CT) and the 2-year incidence of referable diabetic retinopathy (RDR). Methods: This was a prospective cohort study. Patients with type 2 diabetes in Guangzhou, China, aged 30 to 80 years underwent comprehensive examinations, including standard 7-field fundus photography. Macular CT was measured using a commercial swept-source optical coherence tomography (SS-OCT) device (DRI OCT Triton; Topcon, Tokyo, Japan). The relative risk (RR) with 95% confidence intervals (CIs) was used to quantify the association between CT and new-onset RDR. The prognostic value of CT was assessed using the area under the receiver operating characteristic curve (AUC), net reclassification improvement (NRI), and integrated discrimination improvement (IDI). Results: A total of 1345 patients with diabetes were included in the study, and 120 (8.92%) of them had newly developed RDR at the 2-year follow-up. After adjusting for other factors, the increased RDR risk was associated with greater HbA1c (RR = 1.35, 95% CI = 1.17-1.55, P < 0.001), higher systolic blood pressure (SBP; RR = 1.02, 95% CI = 1.01-1.03, P = 0.005), lower triglyceride (TG) level (RR = 0.81, 95% CI = 0.69-0.96, P = 0.015), presence of diabetic retinopathy (DR; RR = 8.16, 95% CI = 4.47-14.89, P < 0.001), and thinner average CT (RR = 0.903, 95% CI = 0.871-0.935, P < 0.001). The addition of average CT improved NRI (0.464 ± 0.096, P < 0.001) and IDI (0.0321 ± 0.0068, P < 0.001) for risk of RDR, and it also improved the AUC from 0.708 (95% CI = 0.659-0.757) to 0.761 (95% CI = 0.719-0.804). Conclusions: CT thinning measured by SS-OCT is an early imaging biomarker for the development of RDR, suggesting that alterations in CT play an essential role in DR occurrence.