Diabetic choroidopathy: a review of the current literature

The Association Between Choroidal Thickness and Meniere's Disease: A Cross-Sectional Study

OBJECTIVE

To evaluate and compare choroidal thickness (CT) between patients with Meniere's disease (MD) and a control group.

METHODS

This case-control analytical study was conducted on 37 subjects with MD and 37 healthy subjects. Subfoveal CT (SCT), large choroidal vessel (LCV) layer thickness, and mean subfoveal LCV thickness/mean SCT ratio were measured using enhanced-depth imaging optical coherence tomography (EDI-OCT) in the eyes on the MD side (ipsilateral), the contralateral eyes, and the control group.

RESULTS

A statistically significant difference was observed in the mean SCT values between the ipsilateral and control groups after adjustment for age, sex, and migraine (p = 0.04). Moreover, there was a statistically significant difference between the mean subfoveal LCV thickness values and the mean subfoveal LCV thickness/mean SCT ratio between the ipsilateral and control groups (p = 0.006, and p < 0.001, respectively). Patients with a duration of disease over three years had a greater mean subfoveal LCV thickness/mean SCT ratio (67.35 ± 11.56 and 60.66 ± 11.27, respectively), which was statistically insignificant (p = 0.08).

CONCLUSION

We found a thicker choroid and Haller layer, and a greater subfoveal LCV thickness/SCT ratio on the MD side compared to the controls. Furthermore, patients with a greater duration of disease had a lower subfoveal LCV thickness/SCT ratio. These findings may reflect the role of the trigeminal vascular system (TVS) and neurovascular pathophysiology in MD patients. More extensive studies are required to reach more definitive conclusions about the association between CT and MD.

LEVEL OF EVIDENCE

4 Laryngoscope, 134:1889-1893, 2024.

Analysis of the Choroidal Structure in the Early Stage of Type 2 Diabetic Retinopathy

BACKGROUND AND OBJECTIVE

Our aim was to evaluate the choroidal structure in the early stage of Type 2 diabetic retinopathy (DR).

MATERIALS AND METHODS

The study included patients with nonproliferative diabetic retinopathy (NPDR) without edema (n = 30, NPDR group), patients with diabetes without retinopathy (n = 30, No DR group), and healthy subjects (n = 33, control group). Choroidal thickness (CT), total choroidal area (TCA), luminal area (LA), stromal area (SA), and choroidal vascularity index (CVI) were evaluated.

RESULTS

The hypertension (HT) rate was highest in patients with NPDR (63.3%), and lowest in the control group (27.3%). Subfoveal, nasal, temporal CT, TCA, and LA were thinner in patients with diabetes compared to the control group for both patients with and without HT, although not significantly. CTs, TCA, LA, and SA were lower in hypertensive patients than patients without HT in all groups. CVI and LA/SA were significantly lower in NPDR group compared to the controls for both patients with and without HT.

CONCLUSION

In patients with diabetes and before clinical retinopathy develops, the thinning of the CT and CVI begins. A decrease in CVI continues as the retinopathy progresses. HT appears to be a factor that can reduce CT, TCA, LA, and SA. [Ophthalmic Surg Lasers Imaging Retina 2024;55:xx-xx.].

Quantitative assessment of OCT and OCTA parameters in diabetic retinopathy with and without macular edema: single-center cross-sectional analysis

Aim

The retinal and choroidal parameters were analyzed to understand the impairment of microcirculation of both retina and choroid in patients with diabetic retinopathy (DR).

Methods

Fifty-five treatment-naive non-proliferative diabetic retinopathy (NPDR) patients (75 eyes) with type 2 diabetes mellitus (T2DM), including 28 patients (36 eyes) with diabetic macular edema (DME) and 27 patients (39 eyes) without DME, and 25 healthy subjects (47 eyes) were enrolled in this study. The following parameters of DR patients with and without DME were evaluated: the foveal avascular zone area (FAZ-a), FAZ perimeter (FAZ-p), FAZ circularity index (FAZ-CI), total subfoveal choroidal area (TCA), luminal area (LA), stromal area (SA), choroidal vascularity index (CVI), choriocapillaris flow area percentage, superficial capillary plexus (SCP), and deep capillary plexus (DCP).

Results

SCP, DCP, and the percentage of choriocapillaris flow area were significantly different between DR patients with and without DME. The DR patients presented lower LA, CVI, and FAZ-CI compared to those of healthy controls (all p < 0.05). The percentage of choriocapillaris flow area in DR patients with and without DME was significantly lower than that in healthy controls (p < 0.05). SCP and DCP were significantly correlated with FAZ-a and FAZ-p but presented insignificant associations with FAZ-CI.

Conclusions

Optical coherence tomography (OCT) and OCT angiography (OCTA) parameters, such as LA, CVI, FAZ-CI, and the percentage of choriocapillaris flow area, were reduced compared to those in controls, indicating that the microcirculations of the retina and choroid in the macular area were impaired in DR patients with DME and without DME.

Interocular Symmetry of Choroidal Parameters in Patients with Diabetic Retinopathy with and without Diabetic Macular Edema

This study focuses on the interocular comparison of choroidal parameters in diabetic patients with diabetic retinopathy (DR) with and without diabetic macular edema (DME), as well as in patients with unilateral DME (present in only one eye). The aim of this study was to determine the symmetry in order to obtain better insights into the pathophysiology of diabetic choroidopathy. This retrospective single-center cross-sectional study included 170 eyes from 85 patients (61 with DR and 24 controls), divided into subgroups depending on the presence of DME. The patients underwent fluorescein angiography and spectral domain optical coherence tomography examination, and the analysis included various choroidal parameters: choroidal thickness, volume, and the choroidal vascularity index (CVI). In terms of the choroidal thickness, one eye of a patient with DR, regardless of the presence, absence, or unilaterality of DME, may be treated as representative for that patient. CVI proved symmetrical for controls and patients with DR without DME. However, there was some asymmetry of CVI in patients with bilateral or unilateral DME. There was no straightforward relationship between choroidopathy and DME. Other mechanisms were also involved in the pathogenesis.

Changes in the choroid detected by ultrawide-field optical coherence tomography angiography in type 2 diabetes mellitus patients without diabetic retinopathy

AIM

The study objective was to investigate the choroidal changes in type 2 diabetes mellitus (T2DM) patients without diabetic retinopathy (DR).

METHODS

This was a cross-sectional study. Controls without diabetes and T2DM patients without DR (NDR) were included. Ultrawide-field (24 × 20 mm2) optical coherence tomography angiography (OCTA) was performed to analyse choroidal thickness and vessel density. All OCTA images were divided into 3 × 3 grids. The grid centre was considered the central area, while the rest was defined as the peripheral area.

RESULTS

No differences between groups were observed in the flow density of the choriocapillaris (CC), choroidal thickness (ChT) and choroidal vascular index (CVI) of the large and medium choroidal vessel (LMCV) in the central area. In the eight peripheral areas, the mean flow density of the CC did not differ between the groups, while the mean CVI and ChT were decreased in the NDR group (P< 0.05). In each peripheral area, the mean CVI and ChT were decreased in the NDR group (P< 0.05, except in the infratemporal area and nasal area for ChT and in the infratemporal area for CVI). In the correlation analysis, both mean peripheral CVI and ChT correlated with age and the duration of diabetes.

CONCLUSION

Early choroidal lesions tended to be peripheral in the LMCV in patients with diabetes without DR and correlated with age and the duration of diabetes.

The Association Between Lipid Profile and Subfoveal Choroidal Thickness in Chinese Patients with Proliferative Diabetic Retinopathy Secondary to Type 2 Diabetes

Introduction

Extensive studies have studied the factors associated with subfoveal choroidal thickness (SFCT). However, studies of the association between lipid profile and SFCT in patients with proliferative diabetic retinopathy (PDR) in type 2 diabetes remain limited. Thus, we aimed to investigate the relationship between lipid profile and SFCT in patients with PDR.

Materials and Methods

This was a retrospective cross-sectional study. The included participants were inpatients who underwent vitrectomy for PDR with type 2 diabetes and contralateral eyes of PDR patients meeting the criteria. Multivariate linear regression analysis was used to determine the independent association between lipid profile and SFCT.

Results

A total of 131 participants with PDR were enrolled in the final analysis. The average age of the participants was 55.76 ± 9.88 years, and the average SFCT was 276.10 ± 92.92 μm. Multivariate linear regression model results showed that in the fully adjusted model, total cholesterol, high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) had a negative association with SFCT (β = -16.51, 95% CI: -29.57, -3.46; P = 0.0148; β = -42.65, 95% CI: -82.60, -2.70; P = 0.0390; β = -17.89, 95% CI: -33.24, -2.54; P = 0.0245, respectively), while triglyceride was not significantly associated with SFCT (β = 5.23, 95% CI: -18.57, 29.02; P = 0.6678). Furthermore, the results of stratified analysis showed that except for triglyceride, the trends of total cholesterol, HDL-C, LDL-C, and SFCT were consistent among different stratifications in participants.

Conclusion

The cholesterol profile had a significant negative association with SFCT in Chinese PDR patients, but triglyceride was not significantly associated with SFCT. This suggests that these systemic imbalances contribute to choroidal changes, and often coexist in diabetic patients.

The Role of Diabetic Choroidopathy in the Pathogenesis and Progression of Diabetic Retinopathy

Diabetic choroidopathy was first described on histopathological specimens of diabetic eyes. This alteration was characterized by the accumulation of PAS-positive material within the intracapillary stroma. Inflammation and polymorphonuclear neutrophils (PMNs) activation are crucial elements in choriocapillaris impairment. The evidence of diabetic choroidopathy in vivo was confirmed with multimodal imaging, which provides key quantitative and qualitative features to characterize the choroidal involvement. The choroid can be virtually affected in each vascular layer, from Haller's layer to the choriocapillaris. However, the damage on the outer retina and photoreceptor cells is essentially driven by a choriocapillaris deficiency, which can be assessed through optical coherence tomography angiography (OCTA). The identification of characteristic features of diabetic choroidopathy can be significant for understanding the potential pathogenic and prognostic implications in diabetic retinopathy.

The Association between Decreased Choriocapillary Flow and Electroretinogram Impairments in Patients with Diabetes

PURPOSE

To evaluate the association between choriocapillary flow (CCF) and electroretinogram (ERG) in patients with diabetes.

METHOD

This was a cross-sectional study. Patients with type 2 diabetes and healthy controls who had undergone both flicker ERG and optical coherence tomography angiography (OCTA) were included, while patients with severe diabetic retinopathy (DR) and macular edema were excluded. Correlations among OCTA and ERG parameters were conducted by generalized linear mixed models (GLMM).

RESULT

One hundred ninety-four eyes of 102 patients with diabetes and fifty-six eyes of 28 controls were included. The implicit time of 30-Hz flicker ERG successively increased, while the amplitudes, inner-retina vessel density and CCF were decreased from the control to the nondiabetic retinopathy (NDR) to DR group. In patients with diabetes, all GLMM models of ERG parameters had statistically significance (P<0.05), and CCF was correlated with ERG parameters (coefficient index=-0.601, P< 0.001 with 16 Td-s implicit time; coefficient index=-0.687, P< 0.001 with 32 Td-s implicit time; coefficient index=0.933, P=0.035 with 32 Td-s amplitude) and the thickness of retinal pigment epithelium, while in the GLMM model of CCF, it was correlated with the thickness of retinal pigment epithelium and the level of glycosylated hemoglobin(both P= 0.001).

CONCLUSION

CCF decreased in patients with diabetes, and it was related with ERG. Choroidopathy and its functional impairment in the retina may occur very early in patients with diabetes by influencing the outer retina.

Comparison of Chorioretinal Parameters in Diabetic Retinopathy with or without Pan-Retinal Photocoagulation Using Ultrawide-Field Swept-Source Optical Coherence Tomography Angiography

INTRODUCTION

To compare structural and vascular parameters in the central and peripheral retina and choroid of eyes diagnosed with severe nonproliferative diabetic retinopathy (NPDR) or proliferative diabetic retinopathy (PDR) with or without pan-retinal photocoagulation (PRP) using ultrawide-field swept-source optical coherence tomography angiography (SS-OCTA).

METHODS

All participants underwent SS-OCTA imaging centered on the fovea. Retinal and choroidal thickness, vessel density of the superficial capillary plexus (SCP), deep capillary plexus (DCP), choroidal capillary plexus (CCP), and choroidal Sattler's and Haller's layer (CSHL) were analyzed in nine grids using built-in angiography analysis software.

RESULTS

A total of 82 eyes from 82 participants were enrolled in this study, including 40 eyes diagnosed with severe NPDR or PDR without PRP and 42 eyes with PRP. Retinal thickness in part grids was higher in eyes with PRP than in eyes without PRP. Vessel density of the SCP in nasal-superior (p = 0.003) grid was lower in eyes with PRP than in eyes without PRP. No significant difference was found in the vessel density of the DCP between the two groups (all p > 0.05). The choroidal thickness and vessel density of the CSHL of all grids were significantly lower in eyes with PRP than in eyes without PRP (all p < 0.05). A statistically significant decrease in vessel density in CCP was found in the superior (p = 0.043), nasal-superior grid (p = 0.003), macular grid (p < 0.001), and optic disc grid (p = 0.001) of eyes with PRP, compared to eyes without PRP. A significant decrease in the vessel density of CSHL was observed in all grids of PDR eyes with PRP compared to PDR eyes without PRP (all p < 0.05). Significant decrease in choroidal thickness was observed in most grids of PDR eyes with PRP, except for macular grid (p = 0.090) and optic disc grid (p = 0.057).

CONCLUSION

Structural and vascular parameters in the central and peripheral retinal and choroidal layers in eyes diagnosed with severe NPDR or PDR with or without PRP could be quantified using a ultrawide-field SS-OCTA. Eyes with PRP showed a significant decrease in choroidal thickness and vessel density of CCP and CSHL, compared with eyes without PRP. This trend was more obvious in eyes with PDR.

[Choroidal changes in patients with diabetes mellitus]

Diabetic retinopathy (DR) is a microvascular complication of diabetes mellitus (DM) and considered one of the leading causes of vision loss worldwide. The choroid supplies blood to the retina, photoreceptors and the retinal pigment epithelium, it is essential for metabolic exchange in the retina. Many experimental studies have reported that choroidal pathology in diabetic patients may play a role in the development of DR. Choroidal thickness (CT) can be used to assess the vascularization of the choroid. Choroidal vascularity index (CVI) is also used as a marker in assessment of choroidal vascularization. Many studies have been conducted to evaluate choroidal changes in various eye diseases. However, the data on CT in DM patients, especially in those with DR, are conflicting. Thus, the choroidal status in diabetic patients with or without DR remains controversial. In this systematic review we analyze a number of articles dedicated to the relationship between structural changes in the choroid in patients with diabetes mellitus and diabetic retinopathy of different stages, paying particular attention to choroidal thickness and certain other parameters that allow assessment of choroidal changes.

Speckle Contrast as Retinal Tissue Integrity Biomarker in Patients with Type 1 Diabetes Mellitus with No Retinopathy

PURPOSE

To study the retinal and choroidal layers in type 1 diabetes mellitus (DM1) without diabetic retinopathy (DR), using speckle contrast of optical coherence tomography (OCT) images as a tissue biomarker in comparison with healthy subjects.

METHODS

OCT Spectralis images of 148 eyes, 84 from DM1 patients without DR signs, and 64 belonging to the control group, were collected. The speckle contrast and thickness of the inner retinal layer (IRL), the outer retinal layer (ORL), and the choroidal layer in the nasal parafoveal area (N3), were prospectively analyzed.

RESULTS

A statistically significant difference (p = 0.001) in the IRL thickness between groups was observed, being thicker in the DM1 group. There were no differences in the ORL and choroidal thicknesses between groups. A statistically significant difference (p = 0.02) in the IRL speckle contrast was obtained, being lower in the DM1 group. The maximum speckle contrast was reached in the ORL for both groups, although in the DM1 group, it occurs closer to the choroid, at 64 ± 8 μm (p = 0.008).

CONCLUSIONS

Statistically significant differences were found in speckle contrast and thickness between the control and the DM1 group, suggesting an IRL alteration of DM1 patients, supporting the retinal neurodegeneration before DR signs are observed.

Early choroidal changes detected by swept-source OCT in type 2 diabetes and their association with diabetic kidney disease

INTRODUCTION

Microvascular changes in eye and kidney shares some common factors in diabetes mellitus (DM). The purpose was to evaluate choroidal thickness (CT) and choriocapillaris (CC) density in patients with type 2 diabetes (T2D) and their association with diabetic kidney disease (DKD) using swept-source optical coherence tomography (SS-OCT).

RESEARCH DESIGN AND METHODS

A cross-sectional study was conducted with patients with T2D with mild or no diabetic retinopathy (DR) and non-diabetic controls. CT was measured with SS-OCT, and CC vascular density was measured with OCT angiography. These parameters were compared with inner retinal layers thickness in patients with and without DKD and non-diabetic controls.

RESULTS

Ninety-three eyes from patients with T2D and 34 eyes from controls volunteers were included. Within the T2D group, 56 eyes with DKD and 37 eyes from patients with no diabetic kidney disease were examined. A statistically significant reduction of CT was observed in patients with DKD compared with controls, with no difference in CC density. There was an association between ganglion cell layer and central choroidal thickness reduction in the DKD group.

CONCLUSIONS

Patients with T2D with DKD showed a decrease in CT with no difference in CC density compared with non-diabetic controls. This thinning might be related to vascular changes of choroidal layers such as Haller's and Sattler's with preservation of CC density, which is crucial for outer retina and retinal pigment epithelium health. Longitudinal studies are warranted to determine the association of choroidal changes with the pathogenesis of diabetes, and its association with early DKD and progression to more severe DR.

Choroidal and Retinal Thicknesses in Type 2 Diabetes Mellitus with Moderate Diabetic Retinopathy Measured by Swept Source OCT

Background: To study choroidal thickness (CT) in type 2 diabetes mellitus (DM2) patients with moderate diabetic retinopathy (DR) and to correlate with changes in retinal thickness (RT) with swept-source OCT (SS-OCT) compared to healthy subjects. Methods: Fifty-four DM2 patients with moderate DR without diabetic macular edema (DME) and 73 age-matched healthy subjects were evaluated using SS-OCT to measure changes in total RT and CT in the nine areas of the Early Treatment Diabetic Retinopathy Study (ETDRS) macular grid. Results: The mean age was 64.06 ± 11.98 years and 60.79 ± 8.62 years in the diabetic and control groups, respectively. Total RT showed statistically significant differences in the temporal inner area, with higher values in the DM2 group (p = 0.010). CT did not show differences between the groups. There was a significant negative correlation between RT and age in all of the outer ETDRS areas and a positive significant correlation in the central area for the DM2 group. There was also a negative significant correlation between CT and age in all of the ETDRS areas except for the inferior inner area. In the DM2 group, a negative correlation was observed between RT and CT in the central area (p = 0.039) and in both horizontal parafoveal areas (temporal inner, p = 0.028; nasal inner, p= 0.003). Conclusion: DM2 patients with moderate DR have no changes with regard to CT. Both CT and RT decreased with age in DM2, showing a negative correlation between these factors in the central and horizontal parafoveal areas of the ETDRS grid.

Imaging-based Assessment of Choriocapillaris: A Comprehensive Review

PURPOSE

Over the past two decades, advancements in imaging modalities have significantly evolved the diagnosis and management of retinal diseases. Through these novel platforms, we have developed a deeper understanding of the anatomy of the choroidal vasculature and the choriocapillaris. The recently developed tools such as optical coherence tomography (OCT) and OCT angiography (OCTA) have helped elucidate the pathological mechanisms of several posterior segment diseases. In this review, we have explained the anatomy of the choriocapillaris and its close relationship to the outer retina and retinal pigment epithelium.

METHODS

A comprehensive search of medical literature was performed through the Medline/PubMed database using search terms: choriocapillaris, choroid, quantification, biomarkers, diabetic retinopathy, age-related macular degeneration, choroidal blood flow, mean blur rate, flow deficit, optical coherence tomography, optical coherence tomography angiography, fluorescein angiography, indocyanine green angiography, OCTA, Doppler imaging, uveitis, choroiditis, white dot syndrome, tubercular serpiginous-like choroiditis, choroidal granuloma, pachychoroid, toxoplasmosis, central serous chorioretinopathy, multifocal choroiditis, choroidal neovascularization, choroidal thickness, choroidal vascularity index, choroidal vascular density, and choroidal blood supply. The search terms were used either independently or combined with choriocapillaris/choroid.

RESULTS

The imaging techniques which are used to qualitatively and quantitatively analyze choriocapillaris are described. The pathological alterations in the choriocapillaris in an array of conditions such as diabetes mellitus, age-related macular degeneration, pachychoroid spectrum of diseases, and inflammatory disorders have been comprehensively reviewed. The future directions in the study of choriocapillaris have also been discussed.

CONCLUSION

The development of imaging tools such as OCT and OCTA has dramatically improved the assessment of choriocapillaris in health and disease. The choriocapillaris can be delineated from the stromal choroid using the OCT and quantified by manual or automated methods. However, these techniques have inherent limitations due to the lack of an anatomical distinction between the choriocapillaris and the stromal choroid, which can be overcome with the use of predefined segmentation slabs on OCT and OCTA. These segmentation slabs help in standardizing the choriocapillaris imaging and obtain repeatable measurements in various conditions such as diabetic retinopathy, age-related macular degeneration, pachychoroid spectrum, and ocular inflammations. Additionally, Doppler imaging has also been effectively used to evaluate the choroidal blood flow and quantifying the choriocapillaris and establishing its role in the pathogenesis of various retinochoroidal diseases. As tremendous technological advancements such as wide-field and ultra-wide field imaging take place, there will be a significant improvement in the ease and accuracy of quantifying the choriocapillaris.

Choroidal Assessment in Patients with Type 2 Diabetes Mellitus and Non-Proliferative Diabetic Retinopathy by Swept-Source Ocular Coherence Tomography and Image Binarization

Background and Objectives: The aim of this study was to evaluate choroidal structure and vascularity indices in patients with non-proliferative diabetic retinopathy (NPDR). Materials and Methods: Sixty-three eyes from sixty-three patients were evaluated: 21 from healthy subjects, 20 with diabetes mellitus (DM) and no diabetic retinopathy (DR), and 22 with DM and non-proliferative diabetic retinopathy without diabetic macular edema (DME). Each patient underwent ocular examination, macular swept-source ocular coherence tomography (SS-OCT) imaging, glycemic control, and systemic high blood pressure (HBP) evaluation. Subfoveal choroidal thickness (SF-CT) was manually assessed on a line scan. Line scan OCT images were exported to ImageJ program. The areas under a 1.5, 3 and 6 mm horizontal line centered on the fovea were assessed by converting the OCT images to binary images, and total choroidal area (TCA), luminal area (LA), stromal area (SA), LA:SA ratio, and choroidal vascularity index (CVI) were evaluated. SF-CT and choroidal parameters were compared between groups, and correlations with ocular and systemic factors were analyzed. Results: SF-CT, TCA, LA, and SA were similar between groups. CVIs were significantly different between groups for all three studied areas (CVI-1.5: 66.21% vs. 66.06% vs. 63.74%, p = 0.003; CVI-3: 65.88% vs. 66.46% vs. 63.79%, p = 0.008; CVI-6: 64.79% vs. 65.40% vs. 63.61%, p = 0.032). NPDR patients had significantly lower CVIs compared to DM patients (p < 0.05). No association of choroidal parameters with glycemic control, DM duration and HBP was found significant (p < 0.05). Conclusions: Choroidal assessment by SS-OCT and image binarization in healthy subjects, subjects with DM without DR, and subjects with DM and NPDR indicated that CVI changes were identifiable and significant in early DR. The lack of association with ocular and systemic factors suggest that CVIs are reliable assessment parameters of choroidal vascular structure.

Correlation between Choroidal Vascularity Index and Outer Retina in Patients with Diabetic Retinopathy

The choroid supplies blood to the outer retina. We quantified outer retinal and choroidal parameters to understand better the pathogenesis of diabetic retinopathy (DR) and diabetic macular edema (DME). The retrospective cross-sectional single-center study included 210 eyes from 139 diabetic patients and 76 eyes from 52 healthy controls. Spectral-domain optical coherence tomography (OCT) was carried out with a Spectralis HRA + OCT imaging device. The outer retinal layer (ORL), outer nuclear layer (ONL), and choroidal thicknesses were assessed along with the choroidal vascularity index (CVI). The presence of DR, whether with DME or without, was associated with choroidal thinning (p < 0.001). Compared with the controls, patients with DR without DME presented with lower ORL and ONL thickness (p < 0.001), whereas those with DR and DME had higher values of both parameters (p < 0.001). Significant correlations between outer retinal and choroidal parameters were found only in patients with DR without DME (ORL with choroidal thickness: p = 0.003, rho = 0.34; ORL with CVI: p < 0.001, rho = 0.49, ONL with CVI: p < 0.027, rho = 0.25). No correlations between choroidal and outer retinal parameters were observed in the controls and patients with DR and concomitant DME. Aside from diabetic choroidopathy, other pathogenic mechanisms seem to predominate in the latter group.

Alterations in the Choroidal Sublayers in Relationship to Severity and Progression of Diabetic Retinopathy

Purpose

To examine the association of baseline choroidal sublayers metrics with the risk of diabetic retinopathy (DR) progression over 2 years, with adjustment for confounding factors that affect choroidal measurements.

Design

Prospective, observational cohort study.

Participants

One hundred three eyes from 62 patients with diabetes mellitus (DM).

Methods

Patients were followed up at 6-month intervals for at least 2 years. Choroidal metrics including choroidal area, choroidal thickness (CT), and choroidal vascularity index were measured for both (1) the choriocapillaris plus Sattler’s layer and (2) the Haller’s layer within the subfoveal and parafoveal region. Cox proportional models were constructed to estimate the relationship between baseline choroidal metrics and DR progression, adjusted for intereye correlation, established risk factors (i.e., duration of DM, glycated hemoglobin [HbA_1c] level, body mass index [BMI], use of insulin, and mean arterial blood pressure [MABP]) and confounding factors of choroidal measurements (i.e., age and axial length). Additional predictive value of choroidal metrics was assessed using the C-statistic.

Main Outcome Measures

Hazard ratios (HRs) calculated by Cox proportional hazards model to demonstrate the associations between baseline choroidal metrics and DR progression.

Results

After adjusting for age, axial length, and intereye correlation, choroidal metrics in Haller’s layer at baseline that were associated with a higher risk of DR progression included increases in subfoveal choroidal area (HR, 2.033; 95% confidence interval [CI], 1.179–3.505; P = 0.011), subfoveal plus parafoveal choroidal area (HR, 1.909; 95% CI, 1.096–3.326; P = 0.022), subfoveal CT (HR, 2.032; 95% CI, 1.181–3.498; P = 0.010), and subfoveal plus parafoveal CT (HR, 1.908; 95% CI, 1.097–3.319; P = 0.022). These associations remained statistically significant after additionally adjusting for duration of DM, HbA_1c level, BMI, use of insulin, and MABP. Addition of these choroidal metrics significantly improved the discrimination for DR progression when compared with established risk factors alone (e.g., duration of DM and HbA_1c; increase in C-statistic ranged from 8.08% to 9.67% [P < 0.05]).

Conclusions

Eyes with a larger choroidal area and CT in Haller’s layer at baseline were associated with a higher risk of DR progression over 2 years.

Optical coherence tomography angiography findings before and after onset of foveal retinal neovascularization in diabetic retinopathy

Purpose

To report a rare case of foveal retinal neovascularization (RNV) in a patient with diabetic retinopathy in whom the retinal microcirculation structure before and after the onset of the disease was evaluated using optical coherence tomography angiography (OCTA).

Observations

A 54-year-old woman with diabetes mellitus was referred to our department for fundus evaluation, and was diagnosed with cataract and severe non-proliferative diabetic retinopathy in the left eye. Two years after we performed cataract surgery and pan-retinal photocoagulation in the left eye, OCTA detected a previously unidentified foveal RNV arising from the perifoveal capillary network. The vitreous retinal interface slab of OCTA and cross-sectional OCT images confirmed that this foveal RNV was an aberrant vessel invading the vitreous cavity.

Conclusions and Importance

The findings in this case indicate that foveal RNV in diabetic retinopathy is derived from vessels outside the foveal avascular zone (FAZ), and OCTA is a useful examination for the diagnostic investigation of foveal RNV.

Choroidal structural alterations in diabetic patients in association with disease duration, HbA1c level, and presence of retinopathy

PURPOSE

To assess choroidal structural changes in diabetic patients in association with disease duration, HbA1c level, and presence of retinopathy.

METHODS

This retrospective cross-sectional study included treatment-naive patients with non-proliferative DR (NPDR) (group 1), diabetic patients without DR (group 2), and healthy subjects (group 3). Patients were also grouped according to the duration of diabetes: long-term group (> 15 years, n = 32) and short-term group (˂ 15 years, n = 28). The choroidal thickness was measured at three points; subfoveal, 1500 μm nasal, and 1500 μm temporal to the fovea. The choroidal area, stromal area, luminal area (LA), and choroidal vascularity index (CVI) were quantified using ImageJ. Partial correlation analysis and one-way analysis of covariance test were performed for statistical analysis.

RESULTS

The study included 30 eyes of 30 treatment-naive patients with NPDR (group 1), 30 eyes of 30 diabetic patients without DR (group 2), and 30 eyes of 30 healthy persons (group 3). The mean subfoveal, nasal, and temporal choroidal thicknesses were decreased in group 1 in comparison with controls (p < 0.001, p = 0.035, and p = 0.005, respectively). The mean LA in group 1 and group 2 were both significantly lower compared to group 3 (group 1 vs. group 3, p = 0.004; group 2 vs. group 3, p = 0.020). CVI was significantly lower in group 1 and group 2 than in controls (group 1 vs. group 3, p = 0.019; group 2 vs. group 3, p = 0.025). CVI was significantly lower in the long-duration group than in the short-duration group (p < 0.001). A moderate negative correlation was found between the duration of diabetes and CVI (r = - 0.467, p < 0.001). A moderate negative correlation was found between HbA1c level and luminal area and CVI (r = - 0.466, p < 0.001, and r = - 0.425, p < 0.001, respectively).

CONCLUSION

Choroidal structure and CVI are altered even in the absence of clinically confirmed retinopathy and these alterations are related to the duration of diabetes.

[Features of structural and microvascular changes of the choroid in angioretinopathy of various etiologies]

PURPOSE

To study structural and microvascular changes in the choroid in patients with chronic kidney disease (CKD), diabetic retinopathy (DR) and arterial hypertension (AH), and their relationship with the level of renal function, carbohydrate metabolism and blood pressure.

MATERIAL AND METHODS

The study involved 172 patients (325 eyes): 56 patients with CKD (109 eyes); 66 patients with DR (121 eyes); 50 patients with AH (95 eyes). All patients underwent comprehensive ophthalmological examination including visometry, biomicroscopy, ophthalmoscopy, optical coherence tomography (OCT) and OCT angiography.

RESULTS

In patients with DR and CKD, a decrease in the thickness of the ganglion cell complex and the inner plexiform layer (GCL+IPL) was noted: in proliferative DR (PDR) - 62.45±4.25 µm, in stage 4-5 CKD - 75.23±6.43 µm; a decrease in choroidal thickness (CT) of minimal values in stage 4-5 CKD (179.9±37.72 µm) and PDR (211.0±40.7 µm). The decrease in choroidal vascularity index (CVI) depended on the stage of CKD and PDR (in PDR - 63.47±1.37, in stage 4-5 CKD - 65.93±2.01). Maximum decrease in perfusion density and vascular density was found in patients with DR (37.22±9.00% and 15.11±3.39 mm, respectively). An increase in the area, perimeter of the foveolar avascular zone (FAZ), and a decrease in the circularity index were noted in all groups, with most pronounced changes in PDR and stage 4-5 CKD. Patients with CKD were found to have strong correlations of CT and CVI with creatinine, urea, proteinuria and glomerular filtration rate (GFR). Patients with diabetes mellitus and PDR were revealed to have strong relations of CT, CVI, GCL+IPL, the area and perimeter of FAZ with creatinine levels and the duration of diabetes mellitus.

CONCLUSION

Choroidal thickness and choroidal vascularity index are important diagnostic markers of disorders of chorioretinal microcirculation that allow stratifying individual assessment of risk factors for progression of both chronic kidney disease and diabetic retinopathy.

SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY BIOMARKERS OF RETINAL HYPERPERMEABILITY AND CHOROIDAL INFLAMMATION AS PREDICTORS OF SHORT-TERM FUNCTIONAL AND ANATOMICAL OUTCOMES IN EYES WITH DIABETIC MACULAR EDEMA TREATED WITH INTRAVITREAL BEVACIZUMAB

PURPOSE

To assess spectral domain optical coherence tomography biomarkers of short-term outcomes in eyes with diabetic macular edema treated with intravitreal bevacizumab.

METHODS

In a prospective interventional case series, 66 eyes with diabetic macular edema underwent 3 monthly intravitreal bevacizumab injections. Best-corrected visual acuity measurement and spectral domain optical coherence tomography were performed at baseline and at 3 months. Multivariate regression analysis was performed to investigate the baseline spectral domain optical coherence tomography parameters as predictors of functional and anatomical outcomes.

RESULTS

Patients with diabetic nephropathy had greater subfoveal choroidal thickness (300.8 ± 35.54 vs. 253.0 ± 50.07 µm, P < 0.01) and were more likely to have subretinal fluid (r = 0.26, P = 0.03) at baseline. Multivariate analysis showed that the extent of external limiting membrane disruption (P = 0.03) and the extent of disorganization of retinal inner layers (P = 0.03) at baseline were predictors of best-corrected visual acuity at 3 months, whereas the extent of disorganization of retinal inner layers (P = 0.04) and duration of diabetes mellitus (P = 0.03) were predictors of central subfield thickness at 3 months.

CONCLUSION

External limiting membrane disruption and disorganization of retinal inner layers, as the spectral domain optical coherence tomography biomarkers of retinal hyperpermeability, can predict short-term outcomes in diabetic macular edema eyes treated with intravitreal bevacizumab.

Assessment of Diabetic Choroidopathy Using Ultra-Widefield Optical Coherence Tomography

Purpose

The purpose of this study was to investigate a confocal scanning laser ophthalmoscopy (cSLO) ultra-widefield (UWF) swept-source optical coherence tomography (S-SOCT) in assessment of diabetic choroidopathy and to evaluate the agreement of measurements with a spectral-domain OCT (SD-OCT) instrument.

Methods

We conducted a cross-sectional study of patients with diabetes evaluating the choroidal vascularity index (CVI) in the nasal, temporal, and central macula segments of a UWF SS-OCT scan centered to the fovea. UWF pseudocolored fundus images were used for diabetic retinopathy (DR) severity staging. The CVI values were compared between different degrees of severity of DR and different posterior-pole sectors with linear mixed models. Central macula CVI measurements were repeated on SD-OCT scans; the interobserver intraclass coefficient (ICC) was calculated between SS-OCT and SD-OCT.

Results

A total of 151 eyes of 85 patients were included. The CVI values decreased from nonproliferative DR to proliferative DR, with high-risk proliferative DR having significantly lower CVI values than moderate to severe nonproliferative DR (P = 0.03). The central macula region was the most evidently affected; the nasal sector was the least affected. The agreement between SS-OCT and SD-OCT was moderate (ICC = 0.50).

Conclusions

Diabetic choroidopathy progresses with worsening of DR toward proliferative disease; choroidal depletion is more prominent in the macula. Caution is recommended in comparing CVI values between different devices.

Translational Relevance

Choroidal vascularity informs about the severity of DR and its complications, such as macular edema. The agreement between readers and between instruments may be suboptimal in certain cases.

Choroidal Structural Changes of Posterior Subtenon Triamcinolone Acetonide Injection in Eyes with Refractory Diabetic Macular Edema

Purpose

To access the choroidal structural changes of posterior subtenon triamcinolone acetonide (PSTA) injection in eyes with refractory diabetic macular edema (DME).

Methods

Patients with refractory DME were enrolled and followed for 4 weeks after switching to PSTA injection. All patients underwent spectral-domain optical coherence tomography with enhanced depth imaging, and the choroidal images were binarized into the luminal area and total choroidal area. Subfoveal choroidal thickness (SFCT) and choroidal vascularity index (CVI) were evaluated before and after switching treatments.

Results

After switching to PSTA treatment, the final best-corrected visual acuity and central subfield thickness in eyes with refractory DME were significantly improved compared to the baseline values (P=0.002 and P < 0.001, respectively). Both the SFCT and CVI decreased during the follow-up period, and significant decreases were observed at 4-week follow-up (P < 0.001 and P=0.012, respectively). The linear regression analysis showed a significant correlation between the baseline SFCT and the final visual outcomes (P=0.047).

Conclusions

The alterations of SFCT and CVI in this study suggest that the choroidal vasculature is involved in the pathogenesis of refractory DME and could be affected by PSTA treatment. SFCT rather than CVI may be a prognostic biomarker for eyes with refractory DME.

Imaging diabetic retinal disease: clinical imaging requirements

Diabetic retinopathy (DR) is a sight-threatening complication of diabetes mellitus (DM) and it contributes substantially to the burden of disease globally. During the last decades, the development of multiple imaging modalities to evaluate DR, combined with emerging treatment possibilities, has led to the implementation of large-scale screening programmes resulting in improved prevention of vision loss. However, not all patients are able to participate in such programmes and not all are at equal risk of DR development and progression. In this review, we discuss the relevance of the currently available imaging modalities for the evaluation of DR: colour fundus photography (CFP), ultrawide-field photography (UWFP), fundus fluorescein angiography (FFA), optical coherence tomography (OCT), OCT angiography (OCTA) and functional testing. Furthermore, we suggest where a particular imaging technique of DR may aid the evaluation of the disease in different clinical settings. Combining information from various imaging modalities may enable the design of more personalized care including the initiation of treatment and understanding the progression of disease more adequately.

Retinal Vascularization Abnormalities Studied by Optical Coherence Tomography Angiography (OCTA) in Type 2 Diabetic Patients with Moderate Diabetic Retinopathy

Diabetic retinopathy (DR) is the most severe and frequent retinal vascular disease that causes significant visual loss on a global scale. The purpose of our study was to evaluate retinal vascularization in the superficial capillary plexus (SCP), the deep capillary plexus (DCP) and the choriocapillaris (CC) and changes in the foveal avascular zone (FAZ) by optical tomography angiography (OCTA) in patients with type 2 diabetes mellitus (DM2) with moderate DR but without diabetic macular oedema (DME). Fifty-four eyes of DM2 with moderate DR (level 43 in the ETDRS scale) and without DME and 73 age-matched healthy eyes were evaluated using OCTA with swept-source (SS)-OCT to measure microvascularization changes in SCP, DCP, CC and the FAZ. The mean ages were 64.06 ± 11.98 and 60.79 ± 8.62 years in the DM2 and control groups, respectively. Visual acuity (VA) was lower in the DM2 patients (p = 0.001), OCTA showed changes in the SCP with a significant diminution in the vascular density and the FAZ area was significantly higher compared to healthy controls, with p < 0.001 at the SCP level. The most prevalent anatomical alterations were peripheral disruption in the SCP (83.3%), microaneurysms (MA) in the SCP and in the DCP (79.6% and 79.6%, respectively) and flow changes in the DCP (81.5%). A significant positive correlation was observed between the DM2 duration and the FAZ area in the SCP (0.304 with p = 0.025). A significant negative correlation was also found between age and CC central perfusion (p < 0.001). In summary, a decrease in the vascular density in DM2 patients with moderate DR without DME was observed, especially at the retinal SPC level. Furthermore, it was found that the FAZ was increased in the DM2 group in both retinal plexuses and was greater in the SCP group.

Choroidal vascularity index changes during the Valsalva manoeuvre in healthy volunteers

PURPOSE

To evaluate the effects of the Valsalva manoeuvre (VM) on the choroidal vascularity index (CVI) in healthy volunteers.

METHODS

This prospective, cross-sectional study included 60 eyes of 30 healthy volunteers. Enhanced depth imaging-optical coherence tomography scans of both eyes involving the fovea were taken, and a 1500 μm subfoveal choroidal area was selected for image binarization with open-access Fiji software. The binarized image was segmented into the stromal area (SA) and luminal area (LA), and CVI was calculated as the ratio (%) of LA to the total choroidal area (TCA). CVI, subfoveal choroidal thickness (SFCT), IOP, systolic and diastolic blood pressure were evaluated at rest and during the VM.

RESULTS

During the VM, a mean ± standard deviation increase in LA (0.02 ± 0.05 mm² , p < 0.001) and CVI (1.72 ± 2.83%, p < 0.001) was observed, whereas SA (-0.02 ± 0.05 mm² , p < 0.001) decreased. There was no significant change in TCA (0.00 ± 0.03 mm² , p = 0.55) or SFCT (1.05 ± 10.92 μm, p = 0.46). There was a moderate positive correlation between the spherical equivalent refractive error (SE) and SFCT both at rest and during VM (r₅₈  = 0.49, p < 0.0005 and r₅₈  = 0.49, p < 0.0005, respectively). However, there was no significant correlation between SE and CVI either at rest or during VM (p = 0.11 and 0.06, respectively). In a multiple linear regression analysis, CVI was only associated with SFCT; however, SFCT was also associated with SE, both at rest and during VM (p < 0.001).

CONCLUSION

Valsalva manoeuvre increases CVI by choroidal vascular dilation as demonstrated by an increase in LA and a decrease in SA. Researchers should be careful about unintentional VM during examinations.

Mapping of choriocapillaris vascular density in young and aged healthy subjects

PURPOSE

To compare macular vascular density (VD) of the choriocapillaris (CC) between young and aged healthy individuals.

METHODS

A cross-sectional study was performed enrolling young and senior healthy individuals of Caucasian race and an axial length (AL) lower than 26 mm, and without systemic or ophthalmological diseases. CC VD was imaged with DRI Triton OCTA using a 6 × 6 mm macular analysis. Internal software delimited CC boundaries and gave colour pictures, which were analysed and codified into numbers, and a grid of 30 × 30 VD values was obtained. Two-dimension (2D) and three-dimension (3D) representations were created.

RESULTS

53 eyes of 53 young healthy individuals and 30 eyes of 30 senior healthy individuals were enrolled. Mean age was 27.17 ± 3.90 years, and 67.00 ± 7.41 years, respectively (p < 0.001). There were no differences in intraocular pressure (IOP) or AL (23.73 ± 0.79 mm, 23.18 ± 0.80 mm, respectively, p = 0.24). There were differences in foveal VD and in temporal perifoveal macula, but not in nasal perifoveal macula. Foveal VD was the highest in both groups.

CONCLUSIONS

Foveal CC VD has been found to be considerably high with this method, and it is the area which most decreases with age. Nasal perifoveal VD is not reduced in older individuals. These outcomes are opposite to other studies using different methods but they are in line with previous histological findings.

Current status and future possibilities of retinal imaging in diabetic retinopathy care applicable to low- and medium-income countries

Diabetic retinopathy (DR) is a leading cause of blindness among adults and the numbers are projected to rise. There have been dramatic advances in the field of retinal imaging since the first fundus image was captured by Jackman and Webster in 1886. The currently available imaging modalities in the management of DR include fundus photography, fluorescein angiography, autofluorescence imaging, optical coherence tomography, optical coherence tomography angiography, and near-infrared reflectance imaging. These images are obtained using traditional fundus cameras, widefield fundus cameras, handheld fundus cameras, or smartphone-based fundus cameras. Fluorescence lifetime ophthalmoscopy, adaptive optics, multispectral and hyperspectral imaging, and multicolor imaging are the evolving technologies which are being researched for their potential applications in DR. Telemedicine has gained popularity in recent years as remote screening of DR has been made possible. Retinal imaging technologies integrated with artificial intelligence/deep-learning algorithms will likely be the way forward in the screening and grading of DR. We provide an overview of the current and upcoming imaging modalities which are relevant to the management of DR.

Alterations in choroidal vascular parameters following panretinal photocoagulation using enhanced-depth imaging optical coherence tomography in diabetic retinopathy

PURPOSE

To investigate the alteration of choroid in patients with very severe non-proliferative diabetic retinopathy (NPDR) or early proliferative diabetic retinopathy (PDR) following panretinal photocoagulation (PRP).

METHODS

Thirty-nine eyes of 21 patients with very severe non-proliferative diabetic retinopathy (NPDR) (19 eyes) and early proliferative diabetic retinopathy (PDR) (20 eyes) were recruited. Enhanced-depth imaging optical coherence tomography at baseline, 1, and 6 months after PRP was employed to measure choroidal parameters including total choroidal area (TCA) and choroidal vascular index (CVI).

RESULTS

In eyes with very severe NPDR, subfoveal TCA decreased non-significantly at month 1, which increased significantly at month 6 (539 ± 131µm², 502 ± 134µm², and 598 ± 168µm² at baseline and months 1 and 6, respectively; P = 0.003). Subfoveal CVI increased at month 1 and then decreased at month 6 (68.25 ± 3.05, 69.74 ± 3.62, and 67.84 ± 1.77 at baseline and months 1 and 6, respectively; P < 0.001). A reverse pattern occurred in eyes with early PDR, a non-significant increase in TCA at month 1 followed by a decrease at month 6 (497 ± 95µm², 514 ± 133µm², and 425 ± 95µm² at baseline and months 1 and 6, respectively; P = 0.011). CVI decreased at month 1 and remained relatively stable at month 6 (69.34 ± 3.11, 68.33 ± 3.41, and 68.50 ± 5.04 at baseline, and months 1 and 6, respectively; P = 0.023). Alteration of choroidal thickness was not statistically significant in both groups.

CONCLUSION

Eyes with very severe NPDR and early PDR exhibit a reverse pattern regarding choroidal indices after PRP.

Ischemic Choroidal Diseases

INTRODUCTION

Ischemic choroidal diseases are an underdiagnosed entity. The clinical pattern varies according to the size and the localisation of the affected vascular structure.

CLINICAL PRESENTATION

In eyes with occlusion of the long posterior ciliary arteries, characteristic triangular patches of choroidal ischemia (Amalric sign) are seen, which in the course of time merge into well-defined areas of atrophy of the retinal pigment epithelium. Above the non-perfused choroidal areas, hyperpigmented, grouped lines appear (Siegrist streaks). Circumscribed ischemia of smaller choroidal arterioles and capillary vessels appears as multifocal, yellowish lesions in the posterior fundus (Elschnig spots). Vortex vein occlusion becomes manifest as exudative haemorrhagic choroidal swelling in the periphery.

CAUSES OF CHOROIDAL ISCHEMIA

Apart from arterial hypertension as a major risk factor, some immunological disorders such as giant cell arteritis and systemic lupus erythematosus and haematological pathologies also affect choroidal perfusion. Furthermore, choroidal ischemia occurs due to local inflammation, as found in eyes with acute multifocal posterior placoid pigment epitheliopathy (APMPPE). Rarely, choroidal infarction is of iatrogenic origin or drug-induced. Recent advances in imaging, such as the introduction of enhanced depth imaging optical coherence tomography (EDI-OCT) and OCT angiography (OCT-A), have improved the visualisation of the choroidal vasculature and complement the classical angiographic procedures. In patients with age-related macular degeneration (AMD) and diabetes, some changes in choroidal blood flow and vascular structure have also been noted. While in AMD the choroidal pathologies correlate with the disease progression and the functional prognosis, the pathophysiological relationship between diabetic choroidopathy and retinopathy is currently unclear.

MANAGEMENT AND CONCLUSION

With regard to the limited therapeutic options for choroidal ischemia, optimisation of the cardiovascular risk profile and the management of accompanying ocular and systemic diseases are essential.

Quantitative Assessment of Choroidal Parameters in Patients with Various Types of Diabetic Macular Oedema: A Single-Centre Cross-Sectional Analysis

Simple Summary

Choroidopathy is one of the components in the pathogenesis of diabetic macular oedema (DME). This study investigated the optical coherence tomography-based choroidal parameters: thickness, volume, choroidal vascularity index (CVI), luminal area (LA), stromal area (SA), and total choroidal area (TCA) in relation to the presence and type of DME (cystoid, diffuse, and with subretinal fluid). Diabetic choroidopathy seems to play a role in the development of DME but is less likely involved in the pathogenesis of specific types thereof.

Abstract

Diabetic macular oedema (DME) is an outcome of multiple, complex and not fully understood mechanisms. The aim of this study was to define the role of choroidopathy in the pathogenesis of various DME types. The retrospective cross-sectional single-centre study included 140 eyes from 105 patients with DME and 76 eyes from 52 non-diabetic controls. The eyes were stratified according to the type of DME: cystoid, diffuse, and with subretinal fluid. Optical coherence tomography-based choroidal parameters: thickness, volume, choroidal vascularity index (CVI), luminal area (LA), stromal area (SA), and total choroidal area (TCA) were compared. Eyes with DME, regardless of the type thereof, had lower choroidal thickness, volume, and CVI values than the controls. Further, the eyes with some specific DME types differed significantly from the controls in terms of LA and SA. While the eyes with various DME types did not differ significantly in terms of their choroidal thickness, volume and CVI, some between-group differences were found in LA, SA and TCA. Diabetic choroidopathy seems to play a role in the development of DME but is less likely involved in the pathogenesis of specific types thereof.

Exploring the choroidal vascular labyrinth and its molecular and structural roles in health and disease

The choroid is a key player in maintaining ocular homeostasis and plays a role in a variety of chorioretinal diseases, many of which are poorly understood. Recent advances in the field of single-cell RNA sequencing have yielded valuable insights into the properties of choroidal endothelial cells (CECs). Here, we review the role of the choroid in various physiological and pathophysiological mechanisms, focusing on the role of CECs. We also discuss new insights regarding the phenotypic properties of CECs, CEC subpopulations, and the value of measuring transcriptomics in primary CEC cultures derived from post-mortem eyes. In addition, we discuss key phenotypic, structural, and functional differences that distinguish CECs from other endothelial cells such as retinal vascular endothelial cells. Understanding the specific clinical and molecular properties of the choroid will shed new light on the pathogenesis of the broad clinical range of chorioretinal diseases such as age-related macular degeneration, central serous chorioretinopathy and other diseases within the pachychoroid spectrum, uveitis, and diabetic choroidopathy. Although our knowledge is still relatively limited with respect to the clinical features and molecular pathways that underlie these chorioretinal diseases, we summarise new approaches and discuss future directions for gaining new insights into these sight-threatening diseases and highlight new therapeutic strategies such as pluripotent stem cell‒based technologies and gene therapy.

Choroidal vascular structures in diabetic patients: a meta-analysis

PURPOSE

Choroidal vascular structures are likely to be affected in diabetic patients. The aim of this study was to conduct a meta-analysis of choroidal vascular structures in diabetic eyes with no diabetic retinopathy (NDR) and healthy control eyes, which was systematically evaluated by various factors involving the measurements.

METHODS

This study identified clinical data from publications in PubMed and web of science until May 2020. Independent retrospective or prospective clinical studies comparing NDR and healthy control eyes regarding choroidal vascular structures were extracted. Five related studies were enrolled, cumulating in a total of 282 diabetic eyes and 511 control eyes examined in this study. Heterogeneity was statistically quantified by I2 statistics, and meta-analysis was performed using a random effects model. This study included 2 different algorisms of binarization determining the ratio of luminal areas in total choroidal areas, both of which were consolidated and called "choroidal vascular ratio."

RESULTS

Meta-analysis clearly showed that the choroidal vascular ratio was significantly lower in NDR eyes than in healthy control eyes (weighted mean difference =  - 2.16; 95%CI: - 3.19 to - 1.13; P < 0.005). Similar results were obtained in sub-analysis based on adjustment of serum HbA1c levels and duration of diabetes.

CONCLUSIONS

The choroidal vascular ratio of NDR eyes was significantly lower than that of healthy control eyes. The ratio might contribute to a better understanding of the pathophysiology involved in the development of diabetic retinopathy, although there was some heterogeneity in primary analysis studies.

Malfunction of outer retinal barrier and choroid in the occurrence and progression of diabetic macular edema

Diabetic macular edema (DME) is the most common cause of vision loss in diabetic retinopathy, affecting 1 in 15 patients with diabetes mellitus (DM). The disruption of the inner blood-retina barrier (BRB) has been largely investigated and attributed the primary role in the pathogenesis and progression in DME, but there is increasing evidence regarding the role of outer BRB, separating the RPE from the underlying choriocapillaris, in the occurrence and evolution of DME. The development of novel imaging technologies has led to major improvement in the field of in vivo structural analysis of the macula allowing us to delve deeper into the pathogenesis of DME and expanding our vision regarding this condition. In this review we gathered the results of studies that investigated specific outer BRB optical coherence tomography parameters in patients with DM with the aim to outline the current status of its role in the pathogenesis and progression of DME and identify new research pathways contributing to the advancement of knowledge in the understanding of this condition.

Higher choroidal thickness and lower choriocapillaris blood flow signal density based on optical coherence tomography angiography in diabetics

Diabetes mellitus (DM) is one of the fastest growing chronic diseases in the world and one of the main causes of vision loss. Whether or not diabetic choroidopathy (DC) is involved in the initiation and progression of diabetic ocular complications needs to be explored. We included 54 diabetic eyes from 36 diabetic patients, and 54 healthy eyes from 32 control subjects after propensity scores matching. All of the subjects were given pupil light and dark adaptation examination and optical coherence tomography angiography (OCTA). Scotopic pupil diameter (SPD), pupil contraction amplitude, and velocity of pupil contraction of the diabetic group were significantly lower than that of the healthy control group (P < 0.05).Choroidal thickness at temporal quadrant (at 750 μm) and superior quadrant (at 1500 μm and 2250 μm) increased in diabetic group compared to control group(P < 0.05).In the diabetic group, choriocapillaris blood flow signal density (CCBFSD) in the macular area (diameter = 2000 μm) were significantly decreased compared with the healthy control group (P < 0.05). Apparent changes in pupil and choroidal blood flow were observed in the diabetic patients.

Choroidal vascularity index: a step towards software as a medical device

The choroidal vascularity index (CVI) is a relatively new parameter, calculated off optical coherence tomography (OCT) images, for the quantitative evaluation of choroid vascularity. It is defined as the ratio of vascular area to the total choroidal area, presented as a percentage. The choroid is an important vascular bed, often implicated in ocular and systemic conditions. Since the introduction of CVI, multiple studies have evaluated its efficacy as a tool for disease prognostication and monitoring progression, with promising results. The CVI was born out of the need for more robust and accurate evaluations of choroidal vasculature, as prior parameters such as choroidal thickness and choroidal vessel diameter had their limitations. In this review, we summarise current literature on the CVI, explain how the CVI is derived and explore its potential integration into future research and translation into clinical care. This includes the application of CVI in various disease states, and ongoing attempts to produce an automated algorithm which can calculate CVI from OCT images.

Analysis of the Choroid and Its Relationship with the Outer Retina in Patients with Diabetes Mellitus Using Binarization Techniques Based on Spectral-Domain Optical Coherence Tomography

(1) Background: We aimed to reveal the relationship between the choroid and the outer retina with optical coherence tomography (OCT) in patients with diabetes mellitus (DM) with mild or no diabetic retinopathy (DR) in order to find early biomarkers for progressing retinopathy. (2) Methods: We performed a prospective study including 61 eyes of patients with type 1 or type 2 DM and 36 eyes of healthy controls. All subjects were imaged with Spectralis OCT. The choroid was assesseed using enhanced depth imaging OCT (EDI-OCT). Binarization of subfoveal choroidal images was done with public domain software, ImageJ (version 1.53a; National Institutes of Health, Bethesda, Maryland, USA). (3) Results: Luminal area, stromal area and total choroidal area were significantly decreased in diabetic patients compared to control: 0.23 ± 0.07 vs. 0.28 ± 0.08, p = 0.012; 0.08 ± 0.03 vs. 0.10 ± 0.04, p = 0.026; 0.31 ± 0.09 vs. 0.38 ± 0.11, p = 0.008. The thickness of retinal pigment epithelium (RPE) correlated positively with the choroidal vascularity index (CVI). The correlations between outer nuclear layer (ONL), photoreceptors (PR) and foveal choroidal thickness (FChT) were moderately negative. (4) Conclusion: Thicker RPE and a thinner PR layer may be assigned the role of early biomarkers signaling the conversion time to progressing retinopathy.

Choroidal Vascularity Index as a Biomarker for Visual Response to Antivascular Endothelial Growth Factor Treatment in Diabetic Macular Edema

PURPOSE

To investigate the choroidal vascularity index (CVI) as a prognostic factor for the visual efficacy of antivascular endothelial growth factor (VEGF) treatment in diabetic macular edema (DME).

METHODS

We retrospectively reviewed 92 DME eyes receiving anti-VEGF treatment, which were stratified as responders (≥5 letters gained) and nonresponders (<5 letters gained or lost). Baseline systematic features and optical coherence tomography features, including the CVI, adjusted ellipsoid zone (EZ) reflectivity, subretinal fluid (SRF), and disorganization of the retinal inner layers (DRIL), were evaluated between the two groups.

RESULTS

The baseline CVI was significantly lower in nonresponders than in responders (0.66 ± 0.05, 0.69 ± 0.05, and 0.72 ± 0.05, p = 0.014). After adjusting for other factors, the baseline CVI, DRIL, SRF, and adjusted EZ reflectivity were significantly associated with visual outcomes (CVI: odds ratio (OR) = 0.17, p = 0.006; adjusted EZ reflectivity: OR = 0.56, p = 0.007; DRIL: OR = 6.71, p = 0.001; and SRF: OR = 0.29, p = 0.008).

CONCLUSION

DME patients with a higher CVI, higher adjusted EZ reflectivity, the presence of SRF, and the absence of DRIL at baseline were more likely to gain >5 letters in visual acuity after anti-VEGF treatment. CVI may serve as a novel biomarker for visual response to anti-VEGF treatment in DME.

Foveal Avascular Zone Does Not Correspond to Choroidal Characteristics in Patients with Diabetic Retinopathy: A Single-Center Cross-Sectional Analysis

PURPOSE

The aim of the study was to compare two non-overlapping blood supply systems of the retina to obtain a better insight into the relation between diabetic macular retinopathy and choroidopathy. Specifically, the study focused on the relationships between (1) retinal vascular changes around the fovea in fluorescein angiography (FA) and (2) choroidal thickness, volume and other parameters assessed by optical coherence tomography (OCT).

PATIENTS AND METHODS

The retrospective cross-sectional single-center study included 210 eyes from 152 patients with diabetic retinopathy (mean age 60.7±12.4 years, 49.3% of women; foveal avascular zone [FAZ] outline: 44.3% grade ≤2, 55.7% grade ≥3). The outline of FAZ, a measure of capillary loss due to ischemic processes, was analyzed on FA according to the Early Treatment Diabetic Retinopathy Study Research Group (ETDRS) standards. The eyes were stratified according to the FAZ outline and size and the presence of clinically significant diabetic macular edema (CSME). Then, resultant groups were compared in terms of the spectral domain OCT parameters: choroidal thickness and volume (within ETDRS subfields), luminal, stromal and total choroidal areas and choroidal vascularity index (based on the foveal scan). Statistical analysis was based on univariate models with the choroidal parameters as independent variables, and age, sex, panretinal photocoagulation, the severity of diabetic retinopathy and CSME as covariates.

RESULTS

No significant relationships were found between the FAZ outline and area and choroidal characteristics of patients with diabetic retinopathy. In patients without CSME, no correlation was observed between the FAZ area and choroidal characteristics. In patients with CSME, no correlation was found between the FAZ area and choroidal characteristics other than the choroidal vascularity index.

CONCLUSION

In patients with diabetic retinopathy, damage to the macular retinal vasculature (FAZ) does not seem to be associated with changes in the choroidal vasculature, and these two processes appear to occur independently.

[Morphometric study of the choroid in pregnant women with disorders of carbohydrate metabolism]

In recent years, much attention is being paid to studying the state of the choroid in various eye pathologies, but changes in the choroid of pregnant women with disorders of glucose metabolism remain unexplored.

PURPOSE

To study choroidal thickness in pregnant women with disorders of carbohydrate metabolism in the III trimester.

MATERIAL AND METHODS

The study included 376 pregnant women in the third trimester of pregnancy: 49 of them had type 1 diabetes (T1D), 248 had gestational diabetes (GD), and 79 were healthy pregnant women who comprised the control group. Three subgroups were distinguished among patients with GD, depending on the timing of the development of GD in the I (160 patients), II (56 patients), or III (32 patients) trimesters. Optical coherence tomography was performed to measure choroidal thickness in the foveal region.

RESULTS

In patients with GD, no significant differences in average indexes of choroidal thickness in subgroups with different timing of diabetes development were observed, however, the pregnant women of the GD subgroup with beginning of its development in the first trimester had the smallest indexes of average choroidal thickness. In pregnant women with GD who received insulin, choroidal thickness was lower than in patients who did not receive it, although statistical significance of that was not established. In patients with T1D and diabetic retinopathy (DR), choroidal thickness was significantly lower compared to patients with T1D without DR, GD and control groups. Obtained data indicates the presence of changes in the choroid and development of diabetic choroidopathy in pregnant women with T1D and DR.

CONCLUSION

The study of choroidal changes in pregnant women with disorders of carbohydrate metabolism can help identify criteria for manifestation of diabetic microangiopathy, choroidopathy, and predict the progression of DR.

Choroidal Vascularity Index in Patients with Type-1 Diabetes Mellitus without Diabetic Retinopathy

Purpose: This study aims to assess choroidal vascularity index (CVI) and choroidal thickness (CT) in patients diagnosed with type 1 diabetes mellitus (DM) and compare them with healthy control subjects.Methods: This retrospective and cross-sectional study includes 43 patients diagnosed with type 1 DM and 43 healthy age/gender-matched subjects as the control group. Enhanced depth imaging optical coherence tomography (EDI-OCT; Spectralis, Heidelberg Engineering GmbH, Heidelberg, Germany) images of all participants were analyzed. CT measurements of five different points (subfoveal, 500 µm temporal, 1500 µm temporal, 500 µm nasal, and 1500 µm nasal to the fovea) were obtained. Choroid images were divided into luminal (LA) and stromal areas (SA) determined by image binarization method. Choroidal vascularity index (CVI) was defined as the ratio of LA to total choroid area (TCA). The effects of age, HbA1c, fasting plasma glucose, duration of DM, mean blood pressure, intraocular pressure, and axial length measurements on CVI were investigated.Results: There was no significant difference between any of the CT measurements of the groups (all p > .05). There was no significant difference between the groups according to TCA (0.82 ± 0.24 vs. 0.80 ± 0.19; p = .065), LA (0.54 ± 0.17 vs. 0.55 ± 0.16; p = .123) and SA (0.28 ± 0.06 vs. 0.25 ± 0.07; p = .068). However, patients had significantly lower CVI compared to control subjects (66.07 ± 3.19 vs. 68.89 ± 2.85, p < .001). Univariate linear regression model revealed that there was a negative correlation between disease duration and CVI (standardized beta coefficient: -0.416, p = .006).Conclusion: According to our findings, reduced CVI may indicate subclinical dysfunction in choroid of patients with type 1 DM.

Diabetic macular edema with pachychoroid features

Background

To investigate the clinical features of diabetic macular edema (DME) in eyes with pachychoroid phenotypes using multimodal retinal imaging.

Methods

We retrospectively reviewed 210 eyes from 210 DME patients and analyzed the clinical and imaging parameters, including visual acuity, central macular thickness (CMT), subfoveal choroidal thickness (SFCT) and neural retina layer thickness (NRT). The DME eyes were divided into two groups: group 1 (80 eyes with submacular detachment [SMD]) and group 2 (130 eyes without SMD). The clinical and imaging parameters of 285 eyes from 285 diabetic patients without DME were collected as a control group.

Results

DME eyes with pachychoroid phenotypes were more frequent in group 1 than in group 2 (53 eyes [66.25%] and 53 eyes [40.77%], respectively, P < 0.001). Pachychoroid phenotypes were identified in 108 (37.90%) of the control eyes. CMT and NRT were greater in group 1 than in group 2. In group 1, 37 eyes had SMD combined with focal edema, and 43 eyes had SMD combined with diffuse-type edema. No significant difference in pachychoroid phenotypes was found between the focal and diffuse types (26 [70.27%] and 27 [62.79%], respectively, P = 0.481). In group 2, 70 eyes had focal-type edema, and 60 eyes had diffuse-type edema. No significant difference in the frequency of pachychoroid phenotypes was found (32 [45.71%] and 21 [35.00%], respectively, P = 0.215). Interestingly, among the 70 eyes with focal edema in group 2, 13 (40.6%) and 5 (13.2%) eyes with and without pachychoroid phenotypes showed no definite microaneurysms, respectively.

Conclusion

SMD and focal edema without definite microaneurysms may be clinical manifestations of DME with pachychoroid phenotypes and possibly related to choroidal circulation disturbance in DME.

Decrease in Choroidal Vascularity Index of Haller's layer in diabetic eyes precedes retinopathy

INTRODUCTION

The study aimed to evaluate Choroidal Vascularity Index (CVI) of Haller's and Sattler's layers and their relationships with choroidal and retinal thickness, volumes measured on enhanced depth imaging-optical coherence tomography (OCT) scans in the eyes of patients without diabetes, patients with diabetes with no diabetic retinopathy (DR) and patients with diabetes and DR.

RESEARCH DESIGN AND METHODS

Retrospective analysis of 165 eyes from 84 Singapore Indian Eye Study-2 study participants (group 1: no diabetes, group 2: diabetes with no DR and group 3: with DR). Groups 1 and 2 were matched by age and gender from group 3.

RESULTS

In the eyes of patients with diabetes without DR, the macular CVI of Haller's but not Sattler's layer was significantly reduced compared with eyes of patients without diabetes. Eyes with >5 years of diabetes have significantly decreased CVI of Sattler's layers (mean difference=0.06 ± 0.10, p=0.04) and also decreased subfoveal choroidal volume (mean difference=0.89 ± 0.16 mm³, p=0.02), compared with those with ≤5 years of diabetes.

CONCLUSION

Diabetic eyes without DR had significantly lower CVI of macular Haller's layer than those of healthy controls. With a longer duration of diabetes, CVI of subfoveal Sattler's layer and choroidal volume continue to decrease, irrespective of diabetic control, suggesting that early diabetic choroidopathy mainly affects larger choroidal veins initially before medium-sized arterioles. The CVI of macular Haller's layer could potentially be used as a marker on spectral domain OCT imaging in newly diagnosed patients with diabetes for the onset of DR and as a possible prognostication tool in diabetic eyes. Future prospective longitudinal studies in diabetic eyes would be useful in establishing the relationship between CVIs of Haller's and Sattler's layer with visual acuity as a marker of photoreceptor health and visual prognosis.

Choroidal Thickness in Diabetes and Diabetic Retinopathy: A Swept Source OCT Study

Purpose

Previous studies on the association between choroidal thickness (CT) and severity of diabetic retinopathy (DR) gave conflicting results. The aim of this study was to evaluate the CT changes in diabetic patients and associated factors in a large sample of Chinese patients with diabetes.

Methods

Type 2 diabetes mellitus patients without history of ocular treatment were recruited from the community health system in Guangzhou, China. The swept source OCT instrument was used to obtain high-definition retina and choroid images. The diabetic retinopathy (DR) status was graded based on the guidelines of the United Kingdom National Diabetic Eye Screening Programme. Univariate and multivariate linear regression analyses was used to explore the association of CT with DR severity, diabetic macular edema (DME), hemoglobin A1c, and vision function.

Results

A total of 1347 patients were included in the final analysis. After adjusting for other factors, the patients with stage R3 DR had significantly thinner CT (β = –29.1 µm, 95% CI –53.8 to –4.4, P = 0.021) in comparison in those with R0. After adjusting for other factors, the CTs were thicker than those in R0 patients with difference of 15.6 µm (95% CI 4.3-26.9, P = 0.007) for outer nasal sector, 15.7 µm (95% CI 3.8-25.5, P = 0.008) for outer inferior, and 12.2 µm (95% CI 0.4-24.0, P = 0.042) for inner inferior sector. The presence of DME and hemoglobin A1c levels did not significantly affect average CT. Higher average CT was significantly associated with better best corrected visual acuity, with a –0.02 LogMAR unit per 100 µm increase in average CT (95% CI –0.03 to –0.01, P < 0.001).

Conclusions

CT increased in the early stage of DR, and further decreased with DR progression. DME was not significantly associated with CT. These findings provide more clues to suggest that choroid alterations play a role in the pathogenesis of DR.

Associations of grip strength with retinal and choroidal thickness in patients with type 2 diabetes mellitus without retinopathy: a cross-sectional study

OBJECTIVE

To evaluate the associations of grip strength with retinal or choroidal thickness in patients with type 2 diabetes mellitus without retinopathy.

DESIGN

Observational study-cross-sectional design.

SETTING AND PARTICIPANTS

This study included the Chinese patients with type 2 diabetes without retinopathy registered in the community health system in Guangzhou, China.

MEASURES

The grip strength in both hands were measured by using a dynamometer. The retinal and choroidal thickness in macular region stratified by Early Treatment Diabetic Retinopathy Study (ETDRS) sectors were measured by a swept-source optical coherence tomography.

RESULTS

A total of 1029 patients were included. Both retinal thickness and choroidal thickness decreased with the lower quartile of grip strength. Regression analyses indicated that the average retinal and choroidal thickness increased by 0.14 µm (95% CI: 0.03 to 0.25 µm, p=0.011) and 0.57 µm (95% CI: 0.03 to 1.11 µm, p=0.037), respectively, for each additional kilogram of grip strength following adjustment for age and sex. Further adjustments were made for axial length, haemoglobin A1c, length of time the patient had diabetes, insulin usage, height, weight and systolic and diastolic blood pressure, which resulted in an average retinal and choroidal thickness increase of 0.13 µm (95% CI: 0.02 to 0.24 µm, p=0.024) and 0.65 µm (95% CI: 0.13 to 1.16 µm, p=0.013), respectively, for each additional kilogram of grip strength. Consistent results were obtained in the analyses in ETDRS 9 sectors.

CONCLUSION

Lower hand grip strength was found to be significantly associated with thinner retinal and choroidal layers in patients with diabetes. Grip strength may provide a useful and easily administered indicator of retinal status in patients with diabetes.

Topographic analysis of retinal and choroidal microvasculature according to diabetic retinopathy severity using optical coherence tomography angiography

PURPOSE

To investigate the topographic changes in the retinal capillary plexus and the choriocapillaris according to the severity of diabetic retinopathy (DR) using optical coherence tomography angiography (OCTA).

METHODS

Subjects were recruited and classified into one of the following four groups: normal controls (n = 52), diabetes without DR (n = 49), non-proliferative DR (n = 51) and proliferative DR (n = 38). Using OCTA, the superficial capillary plexus (SCP), deep capillary plexus (DCP) and the choriocapillaris vessel densities were measured and compared in different macular areas: the fovea (1-mm diameter circular area), parafovea (1-3-mm diameter ring) and perifovea (3-6-mm ring).

RESULTS

With DR progression, vessel densities in the SCP and DCP as well as the choriocapillaris decreased, while the foveal avascular zone area increased (p < 0.001 for all). Compared with controls, the SCP and DCP vessel densities of the diabetes without DR group were decreased in all areas of the macula (p < 0.020 for all), while the choriocapillaris vessel density was decreased only in the perifoveal area (p = 0.823 for the foveal area; p = 0.631 for the parafoveal area; p = 0.039 for the perifoveal area). Multivariate linear regression analyses revealed that all retinal and choroidal microvascular indices were significantly associated with the DR severity.

CONCLUSION

The morphological changes in the macular microvasculature were associated with DR severity. Also, the changes were found to be more vulnerable in the retinal capillary plexuses than the choriocapillaris.

Identifying central serous chorioretinopathy biomarkers in coexisting diabetic retinopathy: a multimodal imaging study

BACKGROUND

To describe clinical and imaging characteristics of patients presenting with diabetic retinopathy (DR) with coexisting acute or chronic central serous chorioretinopathy (CSCR).

METHODS

This was a cross-sectional study which included 54 eyes of 27 patients with coexisting DR and CSCR. Demographic details, prior history of laser, best-corrected visual acuity (BCVA), central macular thickness (CMT), height of neurosensory detachment (NSD), subfoveal choroidal thickness (SFCT), subfoveal large choroidal vessel layer thickness (SF-LCVT), fluorescein angiography and indocyanine green angiography features were recorded. Subanalysis was done for patients with unilateral CSCR. Data was evaluated using Student t-test for quantitative data and χ² test for qualitative data. CSCR between different grades of DR was analysed using analysis of variance.

RESULTS

Prevalence of coexistent CSCR in eyes with DR was 0.4%. Mean age was 53.96±8.79 years, with 25 males. Mean CMT was 349.2±258 μm. Mean SFCT and SF- LCVT of 38 eyes were 376.40±86 μm and 178.80±62.8 μm, respectively. Fifteen eyes had centre involving diabetic macular oedema. Subanalysis of patients with unilateral CSCR showed that the loss of inner segment-outer segment (IS-OS) integrity (p=0.001), photoreceptor footplates at the NSD roof (p=0.001) on optical coherence tomography and dilated choroidal vessels (p=0.05) on indocyanine green angiography were found more often in the CSCR eyes compared with their fellow eyes. Features of CSCR among the different grades of DR were not significantly different between the groups.

CONCLUSION

Our study describes features of a unique subset of patients presenting with coexistent DR and CSCR. Such coexistent nature needs special attention by the clinicians as this may change the treatment approach and alter outcomes.

Deep Learning with Skip Connection Attention for Choroid Layer Segmentation in OCT Images

Since the thickness and shape of the choroid layer are indicators for the diagnosis of several ophthalmic diseases, the choroid layer segmentation is an important task. There exist many challenges in segmentation of the choroid layer. In this paper, in view of the lack of context information due to the ambiguous boundaries, and the subsequent inconsistent predictions of the same category targets ascribed to the lack of context information or the large regions, a novel Skip Connection Attention (SCA) module which is integrated into the U-Shape architecture is proposed to improve the precision of choroid layer segmentation in Optical Coherence Tomography (OCT) images. The main function of the SCA module is to capture the global context in the highest level to provide the decoder with stage-by-stage guidance, to extract more context information and generate more consistent predictions for the same class targets. By integrating the SCA module into the U-Net and CE-Net, we show that the module improves the accuracy of the choroid layer segmentation.

Discordant vascular parameter measurements in diabetic and non-diabetic eyes detected by different optical coherence tomography angiography devices

PURPOSE

To compare quantitative changes in macular parameters in diabetic patients detected by two optical coherence tomography angiography (OCTA) instruments.

METHODS

80 phakic eyes were classified as no diabetes, diabetes without diabetic retinopathy (DR), mild non-proliferative diabetic retinopathy (NPDR), and severe NPDR or proliferative DR (PDR). OCTA was performed using devices from two manufacturers (Zeiss and Heidelberg). Superficial and deeper vascular skeleton density (SVSD, DVSD), superficial and deeper vessel area density (SVAD, DVAD), choriocapillaris flow voids (CCFV), and choroidal flow voids (CFV) were calculated. Inter-device comparisons were performed using the size comparison index (SCI) and the discrepancy index (DI).

RESULTS

The two devices were inconsistent in SVSD, DVSD, DVAD, CCFV and CFV parameters (all P < 0.05). In addition, the SCI was positive for DVAD (all P < 0.001) and negative for SVSD, DVSD, CCFV and CFV in all groups (all P <0.001), except for DVSD in severe NPDR or PDR. The discrepancy index was not significantly different among groups for SVD, SPD, DVD, DPD and CFV (all P> 0.05). The mean DI of CCFV was statistically different between the four groups (P < 0.001).

CONCLUSIONS

The two instruments were largely inconsistent in the measurement of macular parameters relevant to DR. The choice of imaging device can impact OCTA analytics and should be taken into account when drawing conclusions about DR-related changes.