Associations Between Diabetic Retinal Microvasculopathy and Neuronal Degeneration Assessed by Swept-Source OCT and OCT Angiography

Abstract

Purpose: To provide clinical evidence of the associations between retinal neuronal degeneration and microvasculopathy in diabetic retinopathy (DR).Methods: This case-control study included 76 patients (76 eyes) with type 2 diabetes mellitus (DM), and refraction error between −3.0 and +3.0 D. The eyes were assigned into DM (without DR), non-proliferative DR (NPDR), and proliferative DR (PDR) groups. Age-, sex-, and refractive error-matched normal subjects were enrolled as controls. The mean retinal thickness (mRT), the relative mean thickness of the retinal nerve fiber layer (rmtRNFL, mtRNFL/mRT), ganglion cell layer (rmtGCL), ganglion cell complex (rmtGCC) layer, foveal avascular zone area (FAZa), FAZ perimeter (FAZp), FAZ circularity index (FAZ-CI), and vessel density (VD) in superficial capillary plexus (SCP) and deep capillary plexus (DCP) were assessed by swept-source optical coherence tomography (OCT) and OCT angiography (OCTA). Group comparison and Spearman's partial correlation coefficient analysis were applied to evaluate the correlation between these morphological parameters.Results: rmtRNFL, FAZa, and FAZp in SCP and DCP increased with the DR severity (prmtRNFL < 0.001; pFAZa, SCP = 0.001; pFAZa, DCP = 0.005; pFAZp, SCP < 0.001; pFAZp, DCP < 0.001). The rmtGCL, FAZ-CI in SCP and DCP, and VD in DCP decreased with the DR severity (prmtGCL = 0.002, pFAZ−CI, SCP = 0.002; pFAZ−CI, DCP < 0.001, pVD, DCP < 0.001). After controlling age, sex, duration of diabetes, and hypertension, the rmtRNFL, FAZa in SCP and DCP, and FAZp in SCP and DCP were correlated with the severity of DR (p < 0.05), while VD in SCP and DCP, FAZ-CI, and rmtGCL were negatively correlated with the severity of DR (p < 0.05). The rmtGCL was negatively correlated with the FAZa in SCP (r = −0.34, p = 0.002) and DCP (r = −0.23, p = 0.033), and FAZp in SCP (r = −0.37, p = 0.001) and DCP (r = −0.32, p = 0.003), but positively correlated with VD in SCP (r = 0.26, p = 0.016), VD in DCP (r = 0.28, p = 0.012), and FAZ-CI in DCP (r = 0.31, p = 0.006).Conclusions: rmtRNFL, FAZ-CI in SCP and DCP, and FAZp in SCP are strong predictors of the severity of DR. The ganglion cell body loss is highly correlated with increased FAZp and FAZa, decreased FAZ-CI, and reduced VD with the severity of DR.

Case series: Superficial plexus en face may aid distinction of retinal nerve fiber layer loss from diabetic retinal ischemia versus glaucoma

“…This loss matches the "wedge-shaped" capillary dropout extending toward the optic nerve observed in earlymoderate glaucoma cases. 15,16 Additionally, areas of capillary dropout in the glaucoma eye were not devoid of all capillaries (Figs. 2B to D).…”

“…[11][12][13] Research has suggested that diabetic retinal neurodegeneration and vasoregression co-occur, with retinal ischemia associated with focal thinning on OCT B-scans. 14,15 Further, diabetes is associated with progressive retinal nerve fiber and ganglion cell thinning at a rate that rivals moderate progression rates in glaucoma. 3 The eyes in this case series were chosen based on the combination of having diabetes plus optic nerve appearance suggestive of glaucoma.…”

Characterization of Choroidal Morphology and Vasculature in the Phenotype of Pachychoroid Diseases by Swept-Source OCT and OCTA

“…Although more intensive studies have focused on choroidal thickness in recent years, until now, there has been no unified international protocol for the measurement of the choroidal thickness. In this study, ChT in nine macular regions was measured automatically using TOPCON Advanced Boundary Segmentation-TABS software, followed by the computer-aided manual correction of OCT segmentation to minimize the subjective errors [ 19 , 31 ]. Furthermore, we applied SS-OCT for image acquisition, the most ideal method for obtaining SFCT due to its high resolution of choroid and sclera currently with the scanning depth of 2.6 mm, 100,000 scans per second, and 8 μm axial resolution of A-scan.…”

“…The final sample size was determined by the Power Analysis and Sample Size software (PASS 2022, NCSS LLC, Kaysville, UT, USA), based on our pilot study result. The minimum number per arm (sample size) was 13 eyes to detect the difference between the four groups with the designed power (1 − beta = 90%) at 95% confidence level (alpha = 0.05), as we previously described [ 19 ]. We increased the sample size to above 35 eyes in each group, considering the variability (even in normal controls) in the SFCT or VD values.…”

Effects of intensive insulin therapy on the retinal microvasculature in patients with type 2 diabetes mellitus: a prospective observational study

“…Diabetic retinopathy (DR) is the most common microvascular complication of diabetes mellitus and one of the significant causes of blindness in the working-age population [ 1 ]. Chronic high blood glucose levels damage the retinal capillaries and nerves, playing an essential role in the occurrence and development of DR [ 2 ]. Short-term intensive insulin therapy is very important in type 2 diabetes mellitus, which was given by either continuous subcutaneous insulin infusion or multiple daily injections for 14–21 days [ 3 ].…”