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

MiR-185-5p is Involved in Regulating the Abnormal Proliferation of Retinal Microvascular Endothelial Cells via Targeting CXCR4

PURPOSE

This study aimed to explore the expression profile of miR-185-5p in proliferative DR (PDR), and further evaluate its diagnostic value and possible mechanism of miR-185-5p in PDR.

METHODS

The level of miR-185-5p was detected by qRT-PCR. The ROC curve was established to estimate the diagnostic ability of miR-185-5p. Transwell experiment and cell counting kit-8 (CCK-8) assays were conducted to assess the effect of miR-185-5p on the migration and proliferation of human retinal endothelial cells (HRECs) induced by high glucose. Enzyme linked immunosorbent assay (ELISA) was used to detect the concentrations of inflammatory factors. The luciferase reporter gene experiment was used to prove the interaction between miR-185-5p and CXCR4.

RESULTS

Compared to the control group, the expression of miR-185-5p was significantly up-regulated in both the type 2 diabetes mellitus (T2DM) group and the PDR groups, with higher levels in the PDR group than in the T2DM group. The ROC curve reveals that serum miR-185-5p can distinguish PDR patients from T2DM patients. MiR-185-5p levels in HRECs increased significantly after high glucose induction. High glucose induction also promoted the migration, proliferation and inflammation response of HRECs. However, when the intracellular miR-185-5p level was down-regulated by miR-185-5p inhibitor transfection, these effects were inhibited. The luciferase reporter gene assay showed that miR-185-5p directly targets CXCR4.

CONCLUSION

The expression of miR-185-5p is out of balance in PDR and it may be involved in regulating the migration and proliferation of HRECs by regulating CXCR4.

Clinical and imaging characteristics associated with foveal neovascularization in proliferative diabetic retinopathy

PURPOSE

To assess the prevalence of foveal neovascularization (FNV) and its associated clinical features in proliferative diabetic retinopathy (PDR) eyes.

METHODS

Cross-sectional observational study. Participants underwent ultra-widefield photography, optical coherence tomography (OCT), and swept-source OCT angiography (SS-OCTA). FNV was defined as a hyperreflective lesion breaching the internal limiting membrane and displaying flow signal on OCTA, within 1-mm of foveal avascular zone. Vascular metrics were obtained from the ARI Network portal. Ischemic index (ISI) and inner choroid flow deficit percentage were calculated using FIJI from 12 × 12 and 6 × 6-mm scans, respectively. Logistic regression models were used to compare eyes with and without FNV.

RESULTS

We included 249 eyes of 164 patients (age: 58 [50-65] years). FNV was identified in 20 eyes (8%). Univariate logistic regression revealed significant associations between FNV and younger age (p = 0.03), higher maximal HbA1c (p = 0.04), worse visual acuity (VA) (p = 0.01), presence of disorganization of retinal inner layers (DRIL) (p = 0.01), no macular posterior vitreous detachment (PVD) (p = 0.03), neovascularization elsewhere (NVE) and at the disc (NVD) (p = 0.01 and p = 0.001), and greater ISI (p = 0.04). In multivariable analysis, a significant association remained between FNV and worse VA (p = 0.04), NVD (p < 0.001), DRIL (p < 0.001), and absence of macular PVD (p = 0.01). No associations were found with SS-OCTA vascular metrics.

CONCLUSIONS

This study provides a comprehensive characterization of FNV in PDR. FNV was identified in 8% of our cohort, being more prevalent in younger patients with severe PDR, as evidenced by NVD and DRIL presence. The absence of macular PVD may explain its association with younger age.

KEY MESSAGES

What is known • Neovascularization at the fovea occurs rarely in proliferative diabetic retinopathy. • OCT and OCT-angiography can be used to evaluate foveal neovascularization, which may be associated with choroidal vascular abnormalities. What is new • Foveal neovascularization was seen in 8% of eyes with proliferative diabetic retinopathy in this cohort. • Risk factors for foveal neovascularization included younger age, absence of macular posterior vitreous detachment, presence of neovascularization of the disc, and presence of disorganization of retinal inner layers. • We did not identify an association between foveal neovascularization and choroidal perfusion abnormalities in this study.

The role of optical coherence tomography angiography in assessing diabetic choroidopathy: a systematic review

BACKGROUND

Diabetic retinopathy (DR) is a leading cause of vision impairment worldwide, affecting both retinal and choroidal vasculature. While advances in imaging technology, particularly optical coherence tomography angiography (OCTA), provide new opportunities to assess choroidal changes in diabetic patients, the role of OCTA in early diagnosis and monitoring of diabetic choroidopathy remains unclear.

OBJECTIVE

This review aims to evaluate the potential role of OCTA in diagnosing and monitoring diabetic choroidopathy.

METHODS

A systematic review was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. Databases including PubMed, Embase, Cochrane Library, Google Scholar, ISI, and Scopus were searched for studies on diabetic choroidopathy assessed by OCTA. Studies included were peer-reviewed, published in English, and excluded case reports, conference proceedings, and studies on treated DR patients. Two independent reviewers screened articles for eligibility based on predefined criteria.

RESULTS

OCTA allows for non-invasive, high-resolution visualization of retinal and choroidal microvasculature, providing both qualitative and quantitative data. The majority of studies indicate a significant decrease in choroidal perfusion parameters in diabetic patients without DR compared to healthy controls. Conflicting evidence exists regarding the correlation between choriocapillaris flow reduction and DR severity. OCTA may also predict changes in visual function related to choroidal perfusion, though it cannot fully replace clinical examinations.

CONCLUSIONS

OCTA is a valuable tool for early detection and monitoring of diabetic choroidopathy. However, its role is limited by variability in findings and its inability to detect certain features of diabetic microangiopathy. Further studies are needed to clarify its clinical utility and standardize assessment methods.

Association of hypertension defined by the 2017 ACC/AHA guideline and choroidal thickness changes in type 2 diabetes: a 2-year longitudinal study

PURPOSE

This prospective cohort study investigated the longitudinal relationship between hypertension (HTN), defined by the 2017 ACC/AHA guidelines, and changes in choroidal thickness (CT) in patients with type 2 diabetes.

METHODS

Patients aged 30-80 years from the Guangzhou Diabetic Eye Study were categorized into non-HTN, stage 1-HTN, and stage 2-HTN groups based on BP criteria. Macular and parapapillary CT were measured using swept-source optical coherence tomography (SS-OCT). Mixed linear regression models analysed CT decline rates over a median 2.1-year follow-up, adjusting for confounders.

RESULTS

803 diabetes patients were included. Both stage 1-HTN and stage 2-HTN groups showed significantly thinner macular and parapapillary CT compared to non-HTN (all P < 0.05). Stage 2-HTN correlated with reduced macular CT thinning (coef = -11.29 μm/year; 95% CI, -22.36 to -0.22; P = 0.046) after adjustment, but not in the parapapillary area (coef = -4.07 μm/year; 95% CI, -12.89 to 4.74; P = 0.365). Subgroup analyses indicated faster macular CT decline in stage 2-HTN among those <65 years old (coef = -20.31 μm/year; 95% CI, -35.67 to -4.95; P = 0.10), males (coef = -14.1 μm/year; 95% CI, -32.54 to -4.33; P = 0.004), BMI ≥ 25 kg/m2 (coef = -10.24 μm/year; 95% CI, -26.86 to -6.38; P = 0.007), HbA1c > 6.5% (coef = -8.91 μm/year; 95% CI, -13.49 to -4.68; P = 0.001), and diabetes duration <10 years (coef = -12.78 μm/year; 95% CI, -27.48 to -1.91; P = 0.008).

CONCLUSION

Stage 2-HTN is associated with accelerated macular CT loss in diabetic patients, suggesting macular CT measurements could potentially serve as early indicators of systemic hypertension. Further research is needed to establish precise CT cutoff values for clinical use in detecting and monitoring hypertension-related ocular changes.

Associations of Retinal Vessel Geometry and Optical Coherence Tomography Angiography Metrics With Choroidal Metrics in Diabetic Retinopathy

Purpose

To elucidate the mechanism underlying changes in choroidal metrics (choroidal thickness [CT], choroidal vascularity index [CVI], and choriocapillaris [CC] flow deficit [FD]) observed in diabetic retinopathy (DR) and examine the association of choroidal metrics with both retinal vessel geometry and optical coherence tomography angiography (OCTA) metrics.

Methods

Overall, 133 eyes of 133 patients were analyzed retrospectively. Retinal vessel geometry parameters were assessed using semiautomated software. The OCTA metrics and CT were calculated using automated algorithms provided by the manufacturer, whereas the CVI and CC-FD were calculated using ImageJ software from the binarized choroid B-scan image and the CC slab provided by the manufacturer, respectively. To assess the associations among choroidal metrics, retinal vessel geometry, and OCTA metrics, multivariable regression analyses were performed while controlling for clinical features and DR severity.

Results

In the multivariable linear regression analysis, CT (β = -399.84; P = 0.014) and CVI (β = -2.34; P = 0.021) showed significant associations with the arteriole-venule ratio, which is a ratio of central retinal arteriolar equivalent caliber with respect to central retinal venular equivalent caliber. The CC-FD showed a significant association with the fractal dimension of retinal arteriolar network (β = -2.90; P = 0.040). In contrast, the OCTA metrics showed no significant association with the choroidal metrics.

Conclusions

The CT, CVI, and CC-FD in patients with DR were associated with retinal arteriolar geometry parameters rather than OCTA metrics, which indicates an association between choroidal changes and hemodynamic alterations in retinal arterioles and venules.

Diabetes Renders Photoreceptors Susceptible to Retinal Ischemia-Reperfusion Injury

Purpose

Studies have suggested that photoreceptors (PR) are altered by diabetes, contributing to diabetic retinopathy (DR) pathology. Here, we explored the effect of diabetes on retinal ischemic injury.

Methods

Retinal ischemia-reperfusion (IR) injury was caused by elevation of intraocular pressure in 10-week-old BKS db/db type 2 diabetes mellitus (T2DM) mice or C57BL/6J mice at 4 or 12 weeks after streptozotocin (STZ)-induced type 1 diabetes mellitus (T1DM), and respective nondiabetic controls. Retinal neurodegeneration was evaluated by retinal layer thinning, TUNEL staining, and neuron loss. Vascular permeability was evaluated as retinal accumulation of circulating fluorescent albumin. The effects of pretreatment with a sodium-glucose co-transporter (SGLT1/2) inhibitor, phlorizin, were examined.

Results

Nondiabetic control mice exhibited no significant outer retinal layer thinning or PR loss after IR injury. In contrast, db/db mice exhibited significant outer retina thinning (49%, P < 0.0001), loss of PR nuclei (45%, P < 0.05) and inner segment (IS) length decline (45%, P < 0.0001). STZ-induced diabetic mice at 4 weeks showed progressive thinning of the outer retina (55%, by 14 days, P < 0.0001) and 4.3-fold greater number of TUNEL+ cells in the outer nuclear layer (ONL) than injured retinas of control mice (P < 0.0001). After 12 weeks of diabetes, the retinas exhibited similar outer layer thinning and PR loss after IR. Diabetes also delayed restoration of the blood-retinal barrier after IR injury. Phlorizin reduced outer retinal layer thinning from 49% to 3% (P < 0.0001).

Conclusions

Diabetes caused PR to become highly susceptible to IR injury. The ability of phlorizin pretreatment to block outer retinal thinning after IR suggests that the effects of diabetes on PR are readily reversible.

Pachychoroid as a Risk Factor for Exudative Retinal Detachment After Panretinal Photocoagulation: A Report of Two Cases

In this case series of two patients, we discuss pachychoroid as a risk factor for predicting exudative retinal detachment (RD) after panretinal photocoagulation (PRP). The first patient was a 55-year-old diabetic male with unstable proliferative diabetic retinopathy (PDR), serous pigment epithelial detachment (PED), and pachychoroid confirmed via fluorescein angiography (FA) and optical coherence tomography (OCT), who underwent PRP. Post-PRP, the patient complained of visual loss in both eyes. Subsequent FA and OCT confirmed the presence of exudative RD, which resolved after a course of non-steroidal anti-inflammatory eyedrops. The second patient was a 50-year-old male with PDR, serous PED, and pachychoroid confirmed via OCT, who underwent PRP. Post-PRP, he had reduced vision due to exudative RD. His vision improved upon the resolution of the exudative RD after three weeks. Pachychoroid is known to be associated with PDR. In the presence of pachychoroid, PRP-induced inflammation overwhelms the retinal pigment epithelium due to preexisting choroidal thickening, leading to exudative RD. These cases highlight how the identification of pachychoroid before laser PRP can help in predicting exudative RD as a post-procedure complication.

Regional assessment of choroidal vascularity index in patients with pre- and early-stage diabetic retinopathy using ultra-wide-field OCTA

Purpose

To characterize the regional variations of choroidal vascularity index (CVI) in patients with diabetes mellitus (DM) using ultra-wide-field optical coherence tomography angiography (UWF-OCTA) and identify their correlations with the onset of diabetic retinopathy (DR).

Methods

This cross-sectional, monocular-sampling study recruited 141 participants from four age-matched groups: no DM (NDM), no DR with early DM (EDM) and late DM (LDM), and mild-moderate non-proliferative diabetic retinopathy (mNPDR). UWF-OCTA was employed for circular scans centered on the fovea. CVI in the central region (0-1 mm) and four quadrants of the concentric rings with different ranges (1-3, 3-6, 6-9, 9-12, 12-15, 15-18 mm) was obtained for analysis together with their demographic and clinical data. The Area under the receiver operating characteristic curve (AUC) was calculated to assess the diagnostic efficacy for mNPDR and compared using the DeLong test.

Results

The average CVI was lower in patients with mNPDR compared to other groups across all regions. Although there was no significant difference in DM duration between the LDM and mNPDR groups, a notable variance in CVI was observed, particularly (p = 0.0004) in the temporal quadrant of the 15-18 mm range (T18). CVI in T18 region was negatively correlated with creatinine levels, while positively correlated with body mass index and estimated glomerular filtration rate (ps < 0.05). The CVI in the T18 region demonstrated superior diagnostic efficacy (AUC = 0.755), and when combined with those in other regions and clinical data, the AUC rose to 0.907, which was significantly better (p = 0.0280) than using clinical data alone.

Conclusion

Reduced CVI was observed in the most peripheral region, highly predictive for mNPDR and associated with the declining renal function, thus enhancing the potential of UWF-OCTA to integrate into DM management and promote early DR screening.

Detection of choroidal vascular features in diabetic patients without clinically visible diabetic retinopathy by optical coherence tomography angiography: A systemic review and meta-analysis

Researchers have explored choroidal features in the eyes of diabetic patients without clinically visible diabetic retinopathy (DM-NoDR) employing optical coherence tomography angiography (OCTA); however, the results are controversial. We systematically searched PubMed, Embase, and Ovid databases for OCTA studies comparing choroidal parameters between DM-NoDR eyes and healthy controls or nonproliferative diabetic retinopathy (NPDR) eyes. Outcomes included choriocapillaris (CC) perfusion density (PD), flow area (FA), and flow deficits (FD). 36 studies were finally included in the quantitative meta-analysis, involving 1908 DM-NoDR eyes, 792 NPDR eyes, and 1391 healthy control eyes. DM-NoDR eyes had significantly lower CC PD in the foveal region (P = 0.0005) and superior parafoveal region (P = 0.003) than healthy control eyes, but no significant difference was found in other parafoveal subregions (P > 0.05). DM-NoDR eyes were also associated with increased CC FD (P < 0.00001) and decreased CC FA (P < 0.0001) in whole OCTA images with a 3 × 3 mm2 field of view (FOV). Compared with all-stage NPDR eyes, DM-NoDR eyes had higher CC PD in the foveal region (P < 0.0001), parafoveal region (P < 0.00001), and the whole OCTA images with a 6 × 6 mm2 FOV (P < 0.00001). Early choroidal microvascular changes may precede clinically visible DR and can be detected early using OCTA in DM-NoDR eyes.

Retinal Microvascular Alterations in Hidradenitis Suppurativa Patients: A Pilot Study Using Optical Coherence Tomography Angiography

Background: Hidradenitis suppurativa (HS) is a relapsing-remitting inflammatory disease characterized by the progression of asymptomatic nodules to deep-seated lesions and fistula formation that leads to suppuration and scarring. Optical coherence tomography angiography (OCTA) is a new non-invasive imaging technique that carefully analyzes retinal microvasculature networks with high-resolution imaging. Recent studies have demonstrated that retinal vessel density and retinal perfusion reflect systemic inflammatory responses. This study's aim was to analyze OCTA-derived retinal microvasculature parameters to understand if patients affected by HS and without any relevant ocular or systemic comorbidities showed impaired retinal vascular function and morphology. Method: We performed a case-control study of HS patients and age- and sex-matched control cohort. A total of 20 eyes from 10 HS patients and 30 eyes from 15 healthy controls were analyzed, and OCTA-derived microvasculature parameters were compared between groups. Results: OCTA images showed that HS patients, compared to healthy controls, were typically characterized by higher values of the foveal avascular zone (FAZ) both in the superficial capillary plexus (SCP) and in the deep capillary plexus (DCP), and by lower values of vessel density (VD)-SCP, VD-DCP, and vessel length density (VLD)-SCP in the foveal region. These findings partially reflect changes that have been demonstrated in diabetic patients that could be induced by a protracted metabolic or systemic inflammatory dysregulation. Conclusions: In conclusion, OCTA enables large-scale, non-invasive visual screening and follow-up of the retinal vasculature features, providing a new strategy for the prevention and monitoring of visual changes in HS patients.

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.