Early Detection of Microvascular Impairments With Optical Coherence Tomography Angiography in Diabetic Patients Without Clinical Retinopathy: A Meta-analysis

Linking physiology and demographics, non-ocular pathology and pharmaceutical drug use to standard OCT measures of the inner retina: The PPP project

PURPOSE

To assess the associations between physiology and demographics, non-ocular pathology and pharmaceutical drug use against peri-papillary retinal nerve fibre layer thickness (pRNFL T) and other optical coherence tomography (OCT) inner retinal measures in normal, healthy eyes.

METHODS

A retrospective, cross-sectional study of 705 consecutive participants with bilateral normal, healthy optic nerves and maculae. PRNFL Ts, vertical cup/disc ratio (CDR), cup volume and macular ganglion cell layer-inner plexiform layer (GCL-IPL) Ts were extracted from Cirrus OCT scans, then regressed against predictor variables of participants' physiology and demographics (eye laterality, refraction, intraocular pressure [IOP], age, sex, race/ethnicity, etc.) and non-ocular pathology and pharmaceutical drug use according to the World Health Organisation classifications. Associations were assessed for statistical significance (p < 0.05) and clinical significance (|β| > 95% limits of agreement for repeated measures).

RESULTS

A multitude of non-ocular pathology and pharmaceutical drug use were statistically and clinically significantly associated with deviations in standard OCT inner retinal measures, exceeding the magnitude of other factors such as age, IOP and race/ethnicity. Thinner inner retina and larger optic nerve cup measures were linked to use of systemic corticosteroids, sex hormones/modulators, presence of vasomotor/allergic rhinitis and other diseases and drugs (up to -29.3 [-49.88, -8.72] μm pRNFL T, 0.31 [0.07, 0.54] vertical CDR, 0.29 [0.03, 0.54] mm3 cup volume and -10.18 [-16.62, -3.74] μm macular GCL-IPL T; all p < 0.05). Thicker inner retina and smaller optic nerve cup measures were diffusely associated with use of antineoplastic agents, presence of liver or urinary diseases and other diseases and drugs (up to 67.12 [64.92, 69.31] μm pRNFL T, -0.31 [-0.53, -0.09] vertical CDR, -0.06 [-0.11, 0] mm3 cup volume and 28.84 [14.51, 43.17] μm macular GCL-IPL T; all p < 0.05).

CONCLUSION

There are a multitude of systemic diseases and drugs associated with altered OCT inner retinal measures, with magnitudes far exceeding those of other factors such as age, IOP and race/ethnicity. These systemic factors should at least be considered during OCT assessments to ensure precise interpretation of normal versus pathological inner retinal health.

Perfusion Deficits in Diabetes Without Retinopathy Localize to the Perivenular Deep Capillaries Near the Fovea on OCT Angiography

Purpose

To localize early capillary perfusion deficits in patients with diabetes mellitus (DM) without clinical diabetic retinopathy (DR) using averaged OCT angiography (OCTA).

Design

Retrospective cross-sectional study.

Participants

Patients with DM without DR and healthy controls.

Methods

We measured perfusion deficits in the full retina, superficial capillary plexus (SCP), and deep capillary plexus (DCP) on averaged 3 × 3-mm OCTA images. Perfusion deficits were defined as the percentage of retinal tissue located >30 μm from blood vessels, excluding the foveal avascular zone (FAZ). One eye from each patient was selected based on image quality. We measured deficits in the parafoveal region, the 300 μm surrounding the FAZ, and 300 to 1000 μm surrounding the FAZ. If a capillary layer within one of these regions was significantly different in DM without DR compared with controls, we further characterized the location of perfusion deficit as periarteriolar, perivenular, or the capillaries between these 2 zones.

Main Outcome Measures

Location of increased perfusion deficits in patients with DM without DR compared with controls.

Results

Sixteen eyes from 16 healthy controls were compared with 16 eyes from 16 patients with DM without DR (age 45.1 ± 10.7 and 47.4 ± 15.2 years respectively, P = 0.64). Foveal avascular zone area and perfusion deficits in the entire parafovea and the 300 to 1000-μm ring around the FAZ were not significantly different between groups (P > 0.05 for all). Perfusion deficits in 300 μm around the FAZ were significantly increased in patients with DM without DR in full retinal thickness, SCP, and DCP (P < 0.05 for all). When analyzing the perivenular, periarteriolar, and capillary zones, only the perivenular DCP perfusion deficits were significantly increased (5.03 ± 2.92% in DM without DR and 2.73 ± 1.97% in controls, P = 0.014).

Conclusions

Macular perfusion deficits in patients with DM without DR were significantly increased in the region nearest the FAZ, mainly at the perivenular deep capillaries. Further research on these early changes may improve our understanding of the capillaries most susceptible to vascular injury and disruption during diabetes.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Diagnostic application in streptozotocin-induced diabetic retinopathy rats: A study based on Raman spectroscopy and machine learning

Vision impairment caused by diabetic retinopathy (DR) is often irreversible, making early-stage diagnosis imperative. Raman spectroscopy emerges as a powerful tool, capable of providing molecular fingerprints of tissues. This study employs RS to detect ex vivo retinal tissue from diabetic rats at various stages of the disease. Transmission electron microscopy was utilized to reveal the ultrastructural changes in retinal tissue. Following spectral preprocessing of the acquired data, the random forest and orthogonal partial least squares-discriminant analysis algorithms were employed for spectral data analysis. The entirety of Raman spectra and all annotated bands accurately and distinctly differentiate all animal groups, and can identify significant molecules from the spectral data. Bands at 524, 1335, 543, and 435 cm-1 were found to be associated with the preproliferative phase of DR. Bands at 1045 and 1335 cm-1 were found to be associated with early stages of DR.

Optical coherence tomography angiography in diabetic retinopathy: A major review

Diabetic retinopathy (DR) is characterized by retinal vasculopathy and is a leading cause of visual impairment. Optical coherence tomography angiography (OCTA) is an innovative imaging technology that can detect various pathologies and quantifiable changes in retinal microvasculature. We briefly describe its functional principles and advantages over fluorescein angiography and perform a comprehensive review on its clinical applications in the screening or management of people with prediabetes, diabetes without clinical retinopathy (NDR), nonproliferative DR (NPDR), proliferative DR (PDR), and diabetic macular edema (DME). OCTA reveals early microvascular alterations in prediabetic and NDR eyes, which may coexist with sub-clinical neuroretinal dysfunction. Its applications in NPDR include measuring ischemia, detecting retinal neovascularization, and timing of early treatment through predicting the risk of retinopathy worsening or development of DME. In PDR, OCTA helps characterize the flow within neovascular complexes and evaluate their progression or regression in response to treatment. In eyes with DME, OCTA perfusion parameters may be of predictive value regarding the visual and anatomical gains associated with treatment. We further discussed the limitations of OCTA and the benefits of its incorporation into an updated DR severity scale.

Blood Glucose Levels Moderate the Associations Between IGF-1 Levels and Choroidal Metrics in Patients With Diabetes With Acromegaly Without Diabetic Retinopathy

Purpose

To examine the effects of serum growth hormone (GH) and insulin-like growth factor-1 (IGF-1) on choroidal structures with different blood glucose levels in patients with diabetes mellitus (DM) with acromegaly without diabetic retinopathy.

Methods

Eighty-eight eyes of 44 patients with acromegaly were divided into a nondiabetic group (23 patients, 46 eyes) and a diabetic group (21 patients, 42 eyes). Forty-four age- and sex-matched healthy controls and 21 patients with type 2 DM without diabetic retinopathy were also included. Linear regression models with a simple slope analysis were used to identify the correlation and interaction between endocrine parameters and choroidal thickness (ChT), total choroidal area (TCA), luminal area (LA), stromal area (SA), and choroidal vascular index (CVI).

Results

Our study revealed significant increases in the ChT, LA, SA, and TCA in patients with acromegaly compared with healthy controls, with no difference in the CVI. Comparatively, patients with DM with acromegaly had greater ChT than matched patients with type 2 DM, with no significant differences in other choroidal parameters. The enhancement of SA, LA and TCA caused by an acromegalic status disappeared in patients with diabetic status, whereas ChT and CVI were not affected by the interaction. In the diabetic acromegaly, higher IGF-1 (P = 0.006) and GH levels (P = 0.049), longer DM duration (P = 0.007), lower blood glucose (P = 0.001), and the interaction between GH and blood glucose were associated independently with thicker ChT. Higher GH levels (P = 0.016, 0.004 and 0.007), longer DM duration (P = 0.022, 0.013 and 0.013), lower blood glucose (P = 0.034, 0.011 and 0.01), and the interaction of IGF-1 and blood glucose were associated independently with larger SA, LA, and TCA. As blood glucose levels increased, the positive correlation between serum GH level and ChT diminished, and became insignificant when blood glucose was more than 7.35 mM/L. The associations between serum IGF-1 levels and LA, SA, and TCA became increasingly negative, with LA, becoming significantly and negatively associated to the GH levels only when blood glucose levels were more than 8.59 mM/L.

Conclusions

Acromegaly-related choroidal enhancements diminish in the presence of DM. In diabetic acromegaly, blood glucose levels are linked negatively with changes in choroidal metrics and their association with GH and IGF-1.

Translational Relevance

We revealed the potential beneficial impacts of IGF-1 and GH on structural measures of the choroid in patients with DM at relatively well-controlled blood glucose level, which could provide a potential treatment target for diabetic retinopathy.

Comparison of the optical coherence tomography-angiography (OCT-A) vascular measurements between molecularly confirmed MODY and age-matched healthy controls

AIMS

Previous structural, vascular density, and perfusion studies have mostly comprised type 1 and type 2 diabetes, even in the absence of retinopathy. The current study aimed to compare macular vessel density (VD) measurements between maturity-onset diabetes of the young (MODY) patients and controls.

METHODS

The macular VD of superficial, deep retina, and choriocapillaris (CC), and central macular thickness (CMT), foveal avascular zone (FAZ), FAZ perimetry, VD of the total retina at 300 µm around the FAZ (FD), and acirculatory index (AI) measurements were taken and analyzed via OCT-A (RTVue XR 100-2 Avanti, AngioVue) and were compared between molecularly confirmed MODY (glucokinase (GCK) variants) patients and healthy controls.

RESULTS

Twenty-five MODY patients and 30 healthy controls were included in the study. The mean plasma hemoglobin A1c level in the MODY group was 6.39 ± 0.38. The mean age was 13.8 ± 2.1 in the MODY group and was 12.6 ± 2.5 years among controls. There was no significant difference in terms of the age, superficial and deep retinal VD, FAZ, FAZ perimetry, CMT, FD, or AI between the groups. Compared to the healthy controls, a slight but significant increase in the CC-VD was detected in the MODY group, but only in the parafoveal and perifoveal regions (p = 0.034, p = 0.009).

CONCLUSION

The significant CC-VD increase in the MODY group might be associated with hyperglycemia and/or relatively poor and vulnerable peripheral vascular CC perfusion compared to the central. Previous thickness and VD results of childhood or adolescent diabetes were distributed in a wider range, suggesting that various factors, including some not yet clearly defined, may affect the choroidal vasculature independently of glycemia or as a contributing factor.

Advances in Structural and Functional Retinal Imaging and Biomarkers for Early Detection of Diabetic Retinopathy

Diabetic retinopathy (DR), a vision-threatening microvascular complication of diabetes mellitus (DM), is a leading cause of blindness worldwide that requires early detection and intervention. However, diagnosing DR early remains challenging due to the subtle nature of initial pathological changes. This review explores developments in multimodal imaging and functional tests for early DR detection. Where conventional color fundus photography is limited in the field of view and resolution, advanced quantitative analysis of retinal vessel traits such as retinal microvascular caliber, tortuosity, and fractal dimension (FD) can provide additional prognostic value. Optical coherence tomography (OCT) has also emerged as a reliable structural imaging tool for assessing retinal and choroidal neurodegenerative changes, which show potential as early DR biomarkers. Optical coherence tomography angiography (OCTA) enables the evaluation of vascular perfusion and the contours of the foveal avascular zone (FAZ), providing valuable insights into early retinal and choroidal vascular changes. Functional tests, including multifocal electroretinography (mfERG), visual evoked potential (VEP), multifocal pupillographic objective perimetry (mfPOP), microperimetry, and contrast sensitivity (CS), offer complementary data on early functional deficits in DR. More importantly, combining structural and functional imaging data may facilitate earlier detection of DR and targeted management strategies based on disease progression. Artificial intelligence (AI) techniques show promise for automated lesion detection, risk stratification, and biomarker discovery from various imaging data. Additionally, hematological parameters, such as neutrophil-lymphocyte ratio (NLR) and neutrophil extracellular traps (NETs), may be useful in predicting DR risk and progression. Although current methods can detect early DR, there is still a need for further research and development of reliable, cost-effective methods for large-scale screening and monitoring of individuals with DM.

Preliminary research on LncRNA ATP2B2-IT2 in neovascularization of diabetic retinopathy

OBJECTIVE

Diabetic retinopathy (DR) is a common complication of diabetes, and recent findings have shown that long noncoding RNAs (lncRNAs) may be involved in its pathogenesis. Through bioinformatics analysis, we found that lncRNA ATP2B2-IT2 may be involved in this process. This study primarily investigated the expression of the lncRNA ATP2B2-IT2 in human retinal microvascular endothelial cells (HRMECs) under high-glucose conditions and its effects on HRMEC proliferation, migration, and neovascularization.

METHODS

We used RT‒PCR to assess the expression levels of lncRNA ATP2B2-IT2 and vascular endothelial growth factor (VEGF) in HRMECs under normal glucose (5.5 mmol/L) and high glucose (30 mmol/L) conditions. HRMECs were subsequently divided into four groups: the normal glucose (NG), high glucose (HG), high glucose with lncRNA ATP2B2-IT2 silencing (HG + si-lncRNA ATP2B2-IT2), and high glucose with silencing control (HG + si-NC) groups. The expression levels of the lncRNA ATP2B2-IT2 and VEGF in each group were determined using RT‒PCR. Thereafter, cell proliferation, migration, and neovascularization were assessed using CCK-8, Transwell, and tube formation assays, respectively.

RESULTS

RT‒PCR revealed that the expression levels of the lncRNA ATP2B2-IT2 and VEGF were greater in the HG group than in the NG group (P < 0.05). After silencing of the lncRNA ATP2B2-IT2, the expression of VEGF decreased significantly (P < 0.05). Subsequent CCK-8, Transwell, and tube formation assays demonstrated that compared to those in the NG group, the HRMECs in the HG group exhibited significantly increased proliferation, migration, and neovascularization (P < 0.05). However, after silencing of the lncRNA ATP2B2-IT2, the proliferation, migration, and neovascularization of HRMECs were significantly decreased in the HG + si-lncRNA ATP2B2-IT2 group compared to those in the HG group (P < 0.05).

CONCLUSION

LncRNA ATP2B2-IT2 may promote the proliferation, migration and neovascularization of HRMECs under high-glucose conditions.

Associations of retinal microvascular alterations with diabetes mellitus: an OCTA-based cross-sectional study

BACKGROUND

Diabetes, a health crisis afflicting millions worldwide, is increasing rapidly in prevalence. The microvascular complications triggered by diabetes have emerged as the principal cause of renal disease and blindness. The retinal microvascular network may be sensitive to early systemic vascular structural and functional changes. Therefore, this research endeavored to discern the systemic determinants influencing the retinal microvascular network in patients with and without diabetes.

METHODS

The Kailuan Eye Study is a cross-sectional study based on the community-based cohort Kailuan Study. Participants underwent optical coherence tomography angiography (OCTA) (Zeiss Cirrus 5000; Carl Zeiss Meditec) and comprehensive systemic examination. Metrics such as perfusion density (PD), vascular density (VD), foveal avascular zone (FAZ) parameters of the superficial capillary plexus (SCP) in the macula were assessed.

RESULTS

This study included 860 eligible participants (average age = 62.75 ± 6.52 years; 21.9% female), of which 449 were diabetics. People with diabetes had diminished PD and VD in the entire macular and parafoveal regions compared to people without diabetes. Reduced PD in the whole macular region was correlated with higher fasting plasma glucose (FPG, mmol/L) concentration (Beta = -0.19, 95% CI = -0.42 to -0.36, P < 0.001), longer axial length (AL, mm) (Beta = -0.13, 95%CI = -0.48 to -0.25, P = 0.002), and elevated heart rate (Beta = -0.10, 95%CI = -0.14 to -0.19, P = 0.014), after adjusting for younger age (Beta = -0.18, 95%CI = -0.24 to -0.35, P < 0.001), consistent with VD of the whole macular region. A higher FPG level was significantly correlated with lower SCP density of both PD and VD in the macular and parafoveal region (P < 0.05 for all), as well as increased systolic blood pressure and low-density lipoprotein cholesterol concentration (P < 0.01 for all).

CONCLUSIONS

In this large-sample cross-sectional study, OCTA evaluation revealed that high prevalence of diabetes and elevated FPG levels were correlated with reduced retinal VD and PD. Hypertension and hyperlipidemia are important risk factors for the development of atherosclerotic cardiovascular disease but have no significant effect on retinal microvascular abnormalities.

Macular Neural and Microvascular Alterations in Type 2 Diabetes Without Retinopathy: A SS-OCT Study

PURPOSE

To identify specific markers indicative of macular neural and microvascular alterations in individuals with Type 2 Diabetes Mellitus (T2DM) without clinically observable retinopathy.

DESIGN

Prospective cross-sectional study.

METHODS

Using the PLEX Elite 9000, all eyes underwent swept-source optical coherence tomography (SS-OCT) angiography. Quantitative analysis of acquired images compared macular neural and microvascular alterations in T2DM patients without retinopathy to age-matched controls. Precise assessments encompassed measuring the thickness of each individual retinal layer and evaluating macular vascular indices within different capillary plexuses.

RESULTS

Forty-nine T2DM patients and 51 age-matched controls participated. T2DM patients exhibited a significant reduction in the mean macular thickness of the ganglion cell-inner plexiform layer (GC-IPL) (82.5 ± 5.5 µm vs 86.2 ± 5.0 µm, P = .001) and macular retinal nerve fiber layer (RNFL) (45.8 ± 3.0 µm vs 48.1 ± 3.7 µm, P = .001). Furthermore, macular full retinal thickness was significantly lower in diabetic eyes than controls (324.9 ± 16.3 µm vs 332.8 ± 13.7 µm, P = .009). Vascular measurements revealed subtle changes in macular vascular skeleton density within the total capillary plexuses in T2DM patients (0.132 ± 0.005 vs 0.135 ± 0.005, P = .019).

CONCLUSIONS

Metrics derived from SS-OCT, particularly macular RNFL and GC-IPL thicknesses, emerged as superior indicators for the early detection of diabetic retinal disease in individuals with T2DM without clinically observable retinopathy. Further investigations are warranted to comprehensively understand the clinical implications of these findings.

Structural and functional characterization of retinal impairment in T1DM patients without diabetic retinopathy: a 3-year longitudinal study

PURPOSE

To analyze the progression of structural and functional retinal impairment in type 1 diabetes mellitus (T1DM) patients with no clinical signs of diabetic retinopathy (DR) during a 3-year follow-up.

METHODS

This was an observational longitudinal study. Post-pediatric T1DM patients without clinical signs of DR, and sex- and age-matched healthy subjects were recruited at San Raffaele Hospital (Milan, Italy). Each patient underwent a comprehensive ophthalmological evaluation, including optical coherence tomography (OCT), OCT-angiography (OCT-A), retinal static and dynamic vessel analysis (DVA), and microperimetry.

RESULTS

21 eyes of 21 T1DM patients (10 females; 24 ± 2 years old), and 21 age and sex-matched healthy subjects were enrolled. At baseline, T1DM eyes revealed a significantly decreased vessel length density using OCT-A (p < 0.001 and p = 0.046 in 3 × 3 and 6 × 6 mm images) and a significantly increased vessel density index (p = 0.013 and p = 0.087 in 3 × 3 and 6 × 6 mm images) of deep capillary plexus. DVA detected a significantly decreased vessel response to flicker light (p = 0.002). A significantly increased thickness of ganglion cellular layer 6-mm-diameter subfields in inferior and superior quadrants was found in diabetic patients (p < 0.001 in both subfields). At 3-years-follow-up no significant longitudinal changes were disclosed in all analyses.

CONCLUSIONS

Concomitant subclinical microvascular and neurodegenerative damages could be early signs of DR onset that precede functional alterations and clinical signs of DR development. These alterations demonstrated a stable trend over time.

Reduced macular thickness and vascular density in abnormal glucose metabolism patients: A meta-analysis of optical coherence tomography (OCT) and OCT angiography studies

BACKGROUND

Alterations in macular thickness and vascular density before clinically visible diabetic retinopathy (DR) remain inconclusive. This study aimed to determine whether retinal manifestations in abnormal glucose metabolism (AGM) patients differ from those in the healthy individuals.

METHODS

PubMed, Embase, and Web of Science were searched between 2000 and 2021. The eligibility criteria were AGM patients without DR. Primary and secondary outcomes measured by optical coherence tomography (OCT) and OCT angiography (OCTA) were analyzed and expressed as standardized mean differences (SMDs) with 95% confidence intervals (CIs). A random-effects model was used in the data synthesis. The potential publication bias for the variables was evaluated using Egger's test.

RESULTS

A total of 86 observational studies involving 13,773 participants and 15,416 eyes were included. OCT revealed that compared to healthy controls, the total macular thickness of AGM patients was thinner, including the thickness of fovea (-0.24, 95% CI [-0.39, -0.08]; P  = 0.002, I2  = 87.7%), all regions of parafovea (-0.32, 95% CI [-0.54, -0.11]; P  = 0.003; I2  = 71.7%) and the four quadrants of perifovea; the thickness of peripapillary retinal nerve fiber layer (pRNFL), macular retinal nerve fiber layer (mRNFL), and ganglion cell layer (GCL) also decreased. OCTA indicated that the superficial and deep vascular density decreased, the foveal avascular zone (FAZ) area enlarged, and the acircularity index (AI) reduced in AGM individuals.

CONCLUSIONS

Retinal thinning and microvascular lesions have occurred before the advent of clinically detectable DR; OCT and OCTA may have the potential to detect these preclinical changes.

REGISTRATION

PROSPERO; http://www.crd.york.ac.uk/prospero/ ; No. CRD42021269885.

Detection of Retinal Microvascular Changes with Optical Coherence Tomography Angiography in Patients with Acute Leukemia Without Retinopathy

INTRODUCTION

Acute leukemia often affects microcirculation perfusion. This study aimed to investigate retinal microvascular changes in patients with acute leukemia without retinopathy during clinical remission using optical coherence tomography angiography (OCTA) and to determine the correlation of these changes with systemic laboratory values.

METHODS

Thirty-eight patients in remission from acute leukemia with no retinopathy (NLR group) and 36 age-matched healthy individuals (control group) were included in this cross-sectional study. OCTA parameters, including the central foveal thickness (CFT), foveal avascular zone (FAZ) area, FAZ perimeter, acircularity index (AI), foveal density (FD300), and the vessel densities (VDs) of the superficial capillary plexus (SCP), deep capillary plexus (DCP), and choriocapillaris were analyzed in a 6 × 6 mm2 macular scan. Correlation and multiple linear regression analyses were conducted to identify potential systemic characteristics associated with these OCTA metrics.

RESULTS

AI (P = 0.034) and FD300 (P < 0.001) differed significantly between the NLR and control groups. The VD of SCP in the parafovea (P = 0.001) and of DCP in both the parafovea (P = 0.011) and perifovea (P = 0.001) were significantly lower in the NLR group than in the control group. In a multiple linear regression analysis, the reduced VD of the perifoveal DCP was significantly correlated with the increased international normalized ratio (standardized beta [STD β] = - 0.356; P = 0.047).

CONCLUSIONS

Macular microvascular changes can be observed during remission from acute leukemia antecedent to clinically visible retinal lesions. Hematological disturbances may be associated with microvascular impairments in preclinical leukemic retinopathy.

Qi-Ju-Di-Huang-Pill delays the progression of diabetic retinopathy

ETHNOPHARMACOLOGICAL RELEVANCE

Qi-Ju-Di-Huang-Pill (QJDH pill) is a Chinese decoction. Although it is commonly used to treat eye conditions, such as diabetic retinopathy (DR), its exact mechanism of action is unknown.

AIM OF THE STUDY

To investigate the specific mechanism by which QJDH pill slows the progression of diabetic retinopathy (DR) based on animal and cellular experiments.

MATERIAL AND METHODS

The major components of QJDH pill were characterized by ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLCMS/MS). C57BL/6J mice were randomly divided into five groups as follows: normal group (control group), model group (STZ group), low-dosage QJDH pill group (QJDH-L group), medium-dosage QJDH pill group (QJDH-M group) and high-dosage QJDH pill group (QJDH-H group). Changes in water intake, urination, food intake, and body mass were monitored weekly, while changes in blood glucose were monitored monthly. Fluorescein fundus angiography (FFA), optical coherence tomography angiography (OCTA), and optical coherence tomography (OCT) were utilized to analyze the changes in fundus imaging indications. Hematoxylin & eosin (H&E) and transmission electron microscopy (TEM) were employed to examine histopathologic and ultrastructural changes in retina. The levels of interleukin-6 (IL-6), interleukin-17 (IL-17), tumor necrosis factor-α (TNF-α), and vascular endothelial growth factor (VEGF) in peripheral blood were detected using Enzyme-linked immunosorbent assay (ELISA). The mouse retina apoptotic cells were labeled with green fluorescence via terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (Tunel). The protein levels of Bcl-2-Associated X (Bax), B cell lymphoma 2 (Bcl-2), Caspase-3, PI3K, phosphorylated PI3K (p-PI3K), protein kinase B (AKT) and phosphorylated AKT (p-AKT) were quantified by Western blot (WB). The retinal pigment epithelium (RPE) cells were cultured and classified into five groups as follows: normal glucose group (NG group), high glucose group (HG group), high glucose + QJDH pill group (HG + QJDH group), high glucose + inhibitor group (HG + LY294002 group), and high glucose + inhibitor + QJDH pill group (HG + LY294002 + QJDH group). Cell viability and apoptosis were detected via Cell Counting Kit-8 (CCK8) and then analyzed by flow cytometry.

RESULTS

In vivo experiments revealed that the QJDH pill effectively reduced blood glucose, symptoms of increased water intake, elevated urination, increased food intake and decreased body mass in DR mice. QJDH pill also slowed the development of a series of fundus imaging signs, such as retinal microangiomas, tortuous dilatation of blood vessels, decreased vascular density, and thinning of retinal thickness, downregulated IL-6, IL-17, TNF-α, and VEGF levels in peripheral blood, and inhibited retinal cell apoptosis by activating the PI3K/AKT signaling pathway. Moreover, in vitro experiments showed that high glucose environment inhibited RPE cell viability and activated RPE cell apoptosis pathway. In contrast, lyophilized powder of QJDH pill increased RPE cell viability, protected RPE cells from high glucose-induced damage, and decreased apoptosis of RPE cells by activating the pi3k pathway.

CONCLUSION

QJDH pill induces hypoglycemic, anti-inflammatory effects, anti-VEGF and anti-retinal cell apoptosis by activating PI3K/AKT signaling pathway, and thus can protect the retina and slow the DR progression.

Associations between retinal microvascular flow, geometry, and progression of diabetic retinopathy in type 2 diabetes: a 2-year longitudinal study

PURPOSE

To determine the association between retinal blood vessel flow and geometric parameters and the risk of diabetic retinopathy (DR) progression through a 2-year prospective cohort study.

METHODS

Patients with type 2 diabetes mellitus (T2DM) were recruited from a diabetic registry between November 2017 and March 2019. All participants underwent standardized examinations at the baseline and 2-year follow-up visit, and the presence and severity of DR were assessed based on standard seven-field color fundus photographs. They also underwent swept-source optical coherence tomography angiography (OCTA) imaging to obtain measurements of foveal avascular zone area, blood vessel density (VD), fractal dimension (FD), blood vessel tortuosity (BVT) in the superficial capillary plexus (SCP) and deep capillary plexus (DCP).

RESULTS

A total of 233 eyes of 125 patients were included, and 40 eyes (17.17%) experienced DR progression within 2 years. DR progression was significantly associated with lower baseline VD (odds ratio [OR] 2.323 per SD decrease; 95% confidence interval [CI] 1.456-3.708; P < 0.001), lower FD (OR, 2.484 per SD decrease; 95% CI 1.268-4.867; P = 0.008), and higher BVT (OR, 2.076 per SD increase; 95% CI 1.382-3.121; P < 0.001) of the DCP after adjusting for confounding factors. The addition of OCTA metrics improved the predictive ability of the original model for DR progression (area under the curve [AUC] from 0.725 to 0.805; P = 0.022).

CONCLUSIONS

OCTA-derived VD, FD and BVT in the DCP were independent predictors of DR progression and showed additive value when added to established risk models predicting DR progression.

A two-year longitudinal observational study of the peripapillary microvasculature in pediatric type 1 diabetes mellitus patients without visual impairment or diabetic retinopathy

•Neurodegeneration precede microcirculatory deterioration in DR. Early signs can be seen in DM patients without visible DR symptoms, such as glial cell apoptosis and thinner retinal nerve fiber layer.•Peripapillary microvascular abnormalities in the peripapillary region may affect the normal metabolism of neurons and eventually aggravate the process of DR.•Prompting ongoing research to monitor the peripapillary microcirculation and microvasculature among T1DM children for early detection and prevention.•In longitudinal observation, the vessel density of the peripapillary superficial capillary plexus were slightly affected, while vessel density, blood flow, vessel morphological abnormalities and flow impairment area were significantly deteriorated in the deep capillary plexus.•The peripapillary deep capillary plexus is more susceptible and vulnerable to DR progression and could be used as a target for DR screening.

Diabetic Retinopathy and Cardiovascular Disease: A Literature Review

Diabetic complications can be divided into macrovascular complications such as cardiovascular disease and cerebrovascular disease and microvascular complications such as diabetic retinopathy, diabetic nephropathy and diabetic neuropathy. Among them, cardiovascular disease (CVD) is an important cause of death in diabetic patients. Diabetes retinopathy (DR) is one of the main reasons for the increasing disability rate of diabetes. In recent years, some studies have found that because DR and CVD have a common pathophysiological basis, the occurrence of DR and CVD are inseparable, and to a certain extent, DR can predict the occurrence of CVD. With the development of technology, the fundus parameters of DR can be quantitatively analyzed as an independent risk factor of CVD. In addition, the cytokines related to DR can also be used for early screening of DR. Although many advances have been made in the treatment of CVD, its situation of prevention and treatment is still not optimistic. This review hopes to discuss the feasibility of DR in predicting CVD from the common pathophysiological mechanism of DR and CVD, the new progress of diagnostic techniques for DR, and the biomarkers for early screening of DR.

Structural and Functional Retinal Changes in Patients with Mild Cognitive Impairment with and without Diabetes

Our objective is to analyze retinal changes using optical coherence tomography angiography (OCT-A) in patients with mild cognitive impairment (MCI) to characterize structural and vascular alterations. This cross-sectional study involved 117 eyes: 39 eyes from patients with MCI plus diabetes (DM-MCI), 39 eyes from patients with MCI but no diabetes (MCI); and 39 healthy control eyes (C). All patients underwent a visual acuity measurement, a structural OCT, an OCT-A, and a neuropsychological examination. Our study showed a thinning of retinal nerve fiber layer thickness (RNFL) and a decrease in macular thickness when comparing the MCI-DM group to the C group (p = 0.008 and p = 0.016, respectively). In addition, an increase in arteriolar thickness (p = 0.016), a reduction in superficial capillary plexus density (p = 0.002), and a decrease in ganglion cell thickness (p = 0.027) were found when comparing the MCI-DM group with the MCI group. Diabetes may exacerbate retinal vascular changes when combined with mild cognitive impairment.

The OSCAR-MP Consensus Criteria for Quality Assessment of Retinal Optical Coherence Tomography Angiography

BACKGROUND AND OBJECTIVES

Optical coherence tomography angiography (OCTA) is a noninvasive high-resolution imaging technique for assessing the retinal vasculature and is increasingly used in various ophthalmologic, neuro-ophthalmologic, and neurologic diseases. To date, there are no validated consensus criteria for quality control (QC) of OCTA. Our study aimed to develop criteria for OCTA quality assessment.

METHODS

To establish criteria through (1) extensive literature review on OCTA artifacts and image quality to generate standardized and easy-to-apply OCTA QC criteria, (2) application of OCTA QC criteria to evaluate interrater agreement, (3) identification of reasons for interrater disagreement, revision of OCTA QC criteria, development of OCTA QC scoring guide and training set, and (4) validation of QC criteria in an international, interdisciplinary multicenter study.

RESULTS

We identified 7 major aspects that affect OCTA quality: (O) obvious problems, (S) signal strength, (C) centration, (A) algorithm failure, (R) retinal pathology, (M) motion artifacts, and (P) projection artifacts. Seven independent raters applied the OSCAR-MP criteria to a set of 40 OCTA scans from people with MS, Sjogren syndrome, and uveitis and healthy individuals. The interrater kappa was substantial (κ 0.67). Projection artifacts were the main reason for interrater disagreement. Because artifacts can affect only parts of OCTA images, we agreed that prior definition of a specific region of interest (ROI) is crucial for subsequent OCTA quality assessment. To enhance artifact recognition and interrater agreement on reduced image quality, we designed a scoring guide and OCTA training set. Using these educational tools, 23 raters from 14 different centers reached an almost perfect agreement (κ 0.92) for the rejection of poor-quality OCTA images using the OSCAR-MP criteria.

DISCUSSION

We propose a 3-step approach for standardized quality control: (1) To define a specific ROI, (2) to assess the occurrence of OCTA artifacts according to the OSCAR-MP criteria, and (3) to evaluate OCTA quality based on the occurrence of different artifacts within the ROI. OSCAR-MP OCTA QC criteria achieved high interrater agreement in an international multicenter study and is a promising QC protocol for application in the context of future clinical trials and studies.

Retina and microvascular alterations in migraine: a systemic review and meta-analysis

Objective

This study aimed to evaluate the retina and microvascular alterations with optical coherence tomography (OCT) or optical coherence tomography angiography (OCTA) in patients with migraine with aura (MA) and migraine without aura (MO).

Methods

PubMed, Embase, and Cochrane Library databases were searched to find relevant literature on patients with MA or MO using OCT/OCTA devices. The eligible data were analyzed by Stata Software (version 15.0).

Results

There were 16 studies identified, involving 379 eyes with MA, 583 eyes with MO, and 658 eyes of healthy controls. The thickness of the peripapillary retinal nerve fiber layer (pRNFL) of patients with MA decreased significantly in most regions. The foveal avascular zone (FAZ) area and perimeter in MA patients significantly enlarged, while the perfusion density (PD) in the macular deep capillary plexus (mDCP) significantly decreased in the whole image and its subregions except for the fovea, with the PD in radial peripapillary capillary (RPC) decreasing inside the disk. Patients with MO demonstrated a significantly decreased thickness of pRNFL in most regions, and the FAZ parameters were significantly enlarged. No statistical significance was observed in the retina and microvascular features of patients with MA and MO.

Conclusion

The eyes affected by MA and MO demonstrated significantly reduced thickness of pRNFL and enlarged FAZ. Patients with MA showed retinal microvascular impairments, including a decreased PD in mDCP. The OCT and OCTA could detect membrane morphology and circulation status in migraine and might provide the basis for the diagnosis and follow-up of patients with migraine.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, CRD42023397653.

Acteoside inhibits high glucose-induced oxidative stress injury in RPE cells and the outer retina through the Keap1/Nrf2/ARE pathway

Diabetes retinopathy (DR) is one of the most common microvascular complications of diabetes. Retinal pigment epithelial (RPE) cells exposed to a high glucose environment experience a series of functional damages, which is an important factor in promoting the progression of DR. Acteoside (ACT) has strong antioxidant and anti-apoptotic properties, but the mechanism of ACT in DR is not completely clear. Therefore, the purpose of the present study was to explore whether ACT inhibits the damage to RPE cells in a high glucose environment through antioxidative effects to alleviate the DR process. The DR in vitro cell model was constructed by treating RPE cells with high glucose, and the DR in vivo animal model was constructed by injecting streptozotocin (STZ) into the peritoneal cavity of mice to induce diabetes. The proliferation and apoptosis of RPE cells were detected by CCK-8 and flow cytometry assays, respectively. The expression changes in Nrf2, Keap1, NQO1 and HO-1 were evaluated by qRT‒PCR, Western blot and immunohistochemistry analyses. The MDA, SOD, GSH-Px and T-AOC contents were detected by kits. The changes in ROS and nuclear translocation of Nrf2 were observed by immunofluorescence assays. HE staining was used to measure the thickness of the outer nuclear layer (ONL) of the retina, and TUNEL staining was used to detect the number of apoptotic cells in the retinas of mice. In the present study, ACT effectively ameliorated outer retina damage in diabetic mice. In high glucose (HG)-induced RPE cells, ACT treatment had the following effects: improved proliferation, decreased apoptosis, inhibited Keap1 expression, promoted the nuclear translocation and expression of Nrf2, upregulated NQO1 and HO-1 (the target genes of Nrf2) expression, decreased ROS concentration, and increased the levels of the SOD, GSH-Px and T-AOC antioxidant indicators. However, knockdown of Nrf2 reversed the above phenomena, which indicated that the protective function of ACT in HG-induced RPE cells are closely related to Nrf2. In summary, the present study demonstrated that HG-induced oxidative stress injury is inhibited by ACT in RPE cells and the outer retina through the Keap1/Nrf2/ARE pathway.

Central and peripheral changes in the retina and choroid in patients with diabetes mellitus without clinical diabetic retinopathy assessed by ultra-wide-field optical coherence tomography angiography

Background

To explore the central and peripheral retinal and choroidal changes in diabetic patients without clinical diabetic retinopathy (DM-NoDR) using ultra-wide-field swept-source optical coherence tomography angiography (UWF-SS-OCTA).

Methods

67 DM-NoDR eyes and 32 age-matched healthy eyes were recruited. Retinal and choroidal parameters, including qualitative retinal microangiopathy, vessel flow (VFD) and linear density (VLD), thickness, and volume, were measured in the central and peripheral areas of the 24 × 20 mm² UWF-SS-OCTA images.

Results

DM-NoDR eyes had significantly more nonperfusion area and capillary tortuosity than controls in the central and peripheral areas (p < 0.05). The presence of central capillary tortuosity was associated with higher levels of serum creatinine (OR 1.049, 95%CI 1.001-1.098; p = 0.044) and blood urea nitrogen (OR 1.775, 95%CI 1.051-2.998; p = 0.032) in DM-NoDR eyes. For DM-NoDR eyes versus controls, VFD in the 300-μm annulus around the foveal avascular zone, superficial capillary plexus (SCP), and full retina, and SCP-VLD significantly decreased, while VFD in the deep capillary plexus (DCP), retinal thickness, and retinal volume increased (p < 0.05). Analysis in the central and peripheral areas recapitulated all these findings, except for decreased peripheral thickness and volume and no difference in peripheral DCP-VFD. In DM-NoDR eyes, choriocapillaris-VFD, choroidal thickness, and choroidal volume increased in the central area, while VFD in the large and medium choroidal vessel layer decreased in the whole image (p < 0.05).

Conclusion

Retinal and choroidal changes already existed in the central and/or peripheral areas of DM-NoDR eyes. UWF-SS-OCTA, enabling the visualization of the peripheral fundus area, is a promising image technique for the early detection of fundus changes in DM-NoDR patients.

Ocular images-based artificial intelligence on systemic diseases

PURPOSE

To provide a summary of the research advances on ocular images-based artificial intelligence on systemic diseases.

METHODS

Narrative literature review.

RESULTS

Ocular images-based artificial intelligence has been used in a variety of systemic diseases, including endocrine, cardiovascular, neurological, renal, autoimmune, and hematological diseases, and many others. However, the studies are still at an early stage. The majority of studies have used AI only for diseases diagnosis, and the specific mechanisms linking systemic diseases to ocular images are still unclear. In addition, there are many limitations to the research, such as the number of images, the interpretability of artificial intelligence, rare diseases, and ethical and legal issues.

CONCLUSION

While ocular images-based artificial intelligence is widely used, the relationship between the eye and the whole body should be more clearly elucidated.

Early Retinal Microvascular Alterations in Young Type 1 Diabetic Patients without Clinical Retinopathy

The purpose of this study is to identify and quantify preclinical changes with the help of optical coherence tomography angiography (OCTA) within the retinal microcirculation of young type 1 diabetes (T1D) patients without clinical signs of diabetic retinopathy (DR) and to compare these results with those obtained from healthy age-matched subjects. OCTA is currently used for monitoring diabetic retinopathy; however, there is no current consensus on which OCTA parameter alterations predict the first clinical signs of diabetic retinopathy. The main challenge that young patients with T1D face during the course of the disease is that they can rapidly progress to the development of DR, especially during adolescence. Moreover, they also present an increased risk of rapid progression toward advanced stages of DR and vision loss compared to type 2 diabetes patients, indicating the importance of early diagnosis and intervention. The limitations of the currently used screening procedures that led to the conceptualization of our study are the difficulties in performing fluorescein angiography tests for diagnosing the clinical signs of DR on young patients, namely the invasive procedure of dye injection, the risk of allergic reactions and the long duration of the examination. Moreover, given the long life expectancy of young T1D patients, it is essential to identify the preclinical changes in retinal microvasculature before reaching the first clinical signs quantifiable by FFA. The clinical study enrolled 119 subjects aged between 4 and 30 years old with a mean age of 13 years old, comprising 61 T1D patients with a mean duration of the disease of 4 years and 8 months and 58 healthy age-matched subjects for the control group. OCTA scans were performed using the RevoNX 130 OCTA device (Optopol) to evaluate the following retinal parameters: foveal avascular zone (FAZ) area, perimeter and circularity, overall foveal thickness, and superficial and deep vessel densities. Statistically significant differences between the two groups were identified for the following parameters: the FAZ area in the T1D group (0.42 ± 0.17) was larger than the control group (0.26 ± 0.080), the FAZ circularity (0.41 ± 0.11) was decreased compared to the control group (0.61 ± 0.08) and the FAZ perimeter was larger (3.63 ± 0.97) compared to the control group (2.30 ± 0.50). The overall foveal thickness was decreased in the T1D group (222.98 ± 17.33) compared to the control group (230.64 ± 20.82). The total vessel density of the superficial capillary plexus (SCP) on an investigated area of 6 X 6 mm centered around the fovea was decreased in the T1D group (37.4164 ± 2.14) compared to the control group (38.0241 ± 2.44). Our data suggest that specific imaging biomarkers such as FAZ perimeter, area and circularity, decreased overall foveal thickness and decreased vessel density in the SCP precede the clinical diagnosis of DR in young T1D patients and represent useful parameters in quantifying capillary nonperfusion in T1D patients without clinical signs of DR.

Early Retinal Microvascular Changes Assessed with Swept-Source OCT Angiography in Type 1 Diabetes Patients without Retinopathy

Type 1 diabetes is a chronic disease that can lead to vision loss when diabetic retinopathy develops. Retinal microvascular alterations occur before the appearance of clinical signs on a fundus examination. This study aimed to analyze retinal vascular parameters on optical coherence tomography angiography (OCT-A) in patients with type 1 diabetes without diabetic retinopathy in comparison with non-diabetic volunteers. This cross-sectional study was conducted at Dijon University Hospital from 2018 to 2020. Vascular densities were measured using macular OCT-A. In total, 98 diabetes patients and 71 non-diabetic volunteers were enrolled. A statistically significant lower vascular density of the inner circle was found in the superficial capillary plexus (SCP) in the diabetes group (p < 0.01). There was a statistically significant correlation between central vascular density in the deep capillary plexus (DCP) and total daily insulin intake (p = 0.042); furthermore, use of the FreeStyle Libre (FSL) device was associated with higher vascular densities in both the SCP (p = 0.034 for outer circle density) and DCP (p < 0.01 for inner circle density and p = 0.023 for outer circle density). Retinal microvascularization was early-altered in type 1 diabetes, and using the FSL device seemed to preserve retinal microvascularization.

Optic nerve head vessel density in patients with pseudoexfoliation syndrome/glaucoma: a systematic review and meta-analysis

PURPOSE

Exfoliative material has been shown to accumulate in ocular and systemic tissues. We aimed to perform a systematic review and meta-analysis of the current literature evaluating optic nerve head vessel density (VD) using optical coherence tomography angiography (OCTA) in patients with XFS and XFG.

METHODS

Studies were retrieved from PubMed, Scopus, and Web of Science databases. Studies comparing patients with XFS and/or XFG patients to healthy controls, using the optic nerve head-centred 4.5 × 4.5 mm square OCTA scan protocol were included. Pooled results are presented as standardised mean differences with 95% confidence intervals (CI). Meta-regression analysis was performed between mean difference in circumpapillary VD between XFG and controls and mean pRNFL thickness in patients with XFG.

RESULTS

Fifteen studies with 1475 eyes were included in this review. Whole image VD and circumpapillary VD (cpVD) were significantly decreased in patients with XFS [-0.78(95% Cl: -1.08, -0.47); [-0.55(95% Cl: -0.80, -0.30); respectively] and XFG [-1.85(95% CI: -2.33, -1.36); -1.84 (95% CI: -2.30, -1.39); respectively] compared to healthy controls. Furthermore, pRNFL thickness decreased in patients with XFS [-0.55(95% Cl: -0.72, -0.35)] and XFG [-1.78(95% Cl: -2.21, -1.36)] compared to healthy controls. Meta-regression showed that pRNFL thickness decreased with increasing mean cpVD difference in XFG patients compared to healthy controls.

CONCLUSIONS

OCTA provides non-invasive, objective and reproducible assessment of peripapillary VD and is important for the detection of vasculopathy in patients with XFS or XFG. This study provides strong evidence for decreased cpVD in the eyes of patients with XFS and XFG.

Optic nerve head vessel density using OCTA in patients with primary angle closure disease: A systematic review and network meta-analysis

PURPOSE

Elevated intraocular presure secondary to angle closure in angle closure glaucoma is considered the primary mechanism in the development of optic nerve damage. There is evidence that vascular mechanisms may play a role in the pathogenesis of primary angle closure disease (PACD). We aimed to evaluate optic nerve head vessel density in PACD.

METHODS

PubMed, Scopus, and Web of Science were searched. Observational investigations were included. A frequentist network meta-analysis was performed. The primary outcome was circumpapillary vessel density (cpVD), and the secondary outcome was peripapillary retinal nerve fiber layer (pRNFL) thickness.

RESULTS

One thousand twenty four eyes from eleven studies were included in the study. There was no difference in cpVD between the primary angle closure glaucoma (PACG) and acute primary angle closure (APAC) group however, there was a significant decreasing in pRNFL thickness in the PACG group compared to APAC group. In the PACG and APAC group, cpVD and pRNFL thickness were decreased compared to primary angle closure (PAC), primary angle closure suspect (PACS), and control group. There was no difference in cpVD and pRNFL thickness between PAC, PACS and control group.

CONCLUSION

This study has shown that the elevated intraocular pressure is an important factor affecting optical nerve perfusion in PACD. The decreasing in cpVD and RNFL thickness was more severe in the PACG and APAC group.

Exploring various novel diagnostic and therapeutic approaches in treating diabetic retinopathy

Diabetic retinopathy is regarded as a common manifestation of diabetes mellitus, being a prominent cause of visual impairment and blindness. This microvascular complication is marked by the appearance of microaneurysms, elevated vascular permeability, capillary blockage, and proliferation of neovasculature. The etiology behind retinopathy is ambiguous and the efficacy of current treatment strategies is minimal. Early diagnosis of this complication using a biomarker with high sensitivity and specificity is very essential for providing better therapeutic strategies. The current available therapeutic options are limited with various adverse effects. Laser treatment is not beneficial in all the situations, economic constraints being the major challenge. Surgical interventions are employed when pharmacotherapy and laser treatment fail. New pharmacological treatments are becoming a necessity for treating the condition. This review highlights the use of various diagnostic tools, emerging biomarkers for early detection of diabetic retinopathy, pathological mechanisms associated with the disease, current therapeutic approaches used and future strategies for more enhanced treatment options and more potent pharmacological actions.

Rates of Choroidal and Neurodegenerative Changes Over Time in Diabetic Patients Without Retinopathy: A 3-Year Prospective Study

PURPOSE

To evaluate the longitudinal changes of retinal neurodegeneration and choroidal thickness in diabetic patients with and without diabetic retinopathy (DR).

DESIGN

Prospective observational cohort study.

METHODS

This prospective observational cohort study recruited type 2 diabetic patients from a community registry in Guangzhou. All participants underwent annual ocular examinations via swept-source optical coherence tomography that obtained choroid thickness (CT), retinal thickness (RT), and ganglion cell-inner plexiform layer (GC-IPL) thickness. The changes in GC-IPL, CT, and RT between patients who developed incident DR (IDR) or remained non-DR (NDR) were compared during a 3-year follow-up.

RESULTS

Among 924 patients, 159 (17.2%) patients developed IDR within the 3-year follow-up. A reduction in GC-IPL, RT, and CT was observed in NDR and IDR; however, CT thinning in patients with IDR was significantly accelerated, with an average CT reduction of -6.98 (95% CI: -8.26, -5.71) μm/y in patients with IDR and -3.98 (95% CI: -4.60, -3.36) μm/y in NDR patients (P < .001). Reductions in average GC-IPL thickness over 3 years were -0.97 (95% CI: -1.24, -0.70) μm/y in patients with IDR and -0.76 (95% CI: -0.82, -0.70) μm/y in NDR patients (P = .025). After adjusting for confounding factors, the average CT and GC-IPL thinning were significantly faster in patients with IDR compared with those who remained NDR by 2.09 μm/y (95% CI: 1.01, 3.16; P = .004) and -0.29 μm/y (95% CI: -0.49, -0.09; P = .004), respectively. The RT in the IDR group increased, whereas the RT in the NDR group decreased over time, with the adjusted difference of 2.09 μm/y (95% CI: 1.01, 3.16; P < .001) for central field RT.

CONCLUSIONS

The rate of retinal neurodegeneration and CT thinning were significantly different between the eyes that developed IDR and remained NDR during the 3-year follow-up, but both groups observed thickness reduction. This indicates that GC-IPL and CTs may decrease before the clinical manifestations of DR.

Deep Learning in Optical Coherence Tomography Angiography: Current Progress, Challenges, and Future Directions

Optical coherence tomography angiography (OCT-A) provides depth-resolved visualization of the retinal microvasculature without intravenous dye injection. It facilitates investigations of various retinal vascular diseases and glaucoma by assessment of qualitative and quantitative microvascular changes in the different retinal layers and radial peripapillary layer non-invasively, individually, and efficiently. Deep learning (DL), a subset of artificial intelligence (AI) based on deep neural networks, has been applied in OCT-A image analysis in recent years and achieved good performance for different tasks, such as image quality control, segmentation, and classification. DL technologies have further facilitated the potential implementation of OCT-A in eye clinics in an automated and efficient manner and enhanced its clinical values for detecting and evaluating various vascular retinopathies. Nevertheless, the deployment of this combination in real-world clinics is still in the "proof-of-concept" stage due to several limitations, such as small training sample size, lack of standardized data preprocessing, insufficient testing in external datasets, and absence of standardized results interpretation. In this review, we introduce the existing applications of DL in OCT-A, summarize the potential challenges of the clinical deployment, and discuss future research directions.

Macular microcirculation changes after repair of rhegmatogenous retinal detachment assessed with optical coherence tomography angiography: A systematic review and meta-analysis

Purpose: The aim of the study was to investigate microcirculation changes in the macula evaluated by optical coherence tomography angiography (OCTA)in patients receiving anatomical repair after surgery for rhegmatogenous retinal detachment (RRD). Methods: A literature search was conducted in PubMed, EMBASE, Web of Science and the Cochrane Library. Studies including patients with macula-on or macula-off RRD and repaired successfully through primary surgery were selected. Foveal avascular zone (FAZ) area and macular vascular density (VD) in both the superficial capillary plexus (SCP) and deep capillary plexus (DCP) were analyzed using RevMan 5.4 software. Results: Twelve studies including 430 RRD eyes and 430 control eyes were selected. In eyes with macula-on RRD, FAZ area, VD in the foveal SCP and DCP, and VD in the parafoveal SCP and DCP were not altered compared with control eyes, after the retina was reattached. In eyes with macula-off RRD that was repaired successfully through surgery, FAZ area in the DCP (0.13 mm², 95% CI: 0.02 to 0.25, p = 0.02) remained enlarged compared with control eyes. Meanwhile, VD in the foveal DCP was also significantly reduced (-3.12%, 95% CI: -6.15 to -0.09%, p = 0.04), even though retinal reattachment was achieved by surgery in eyes with macula-off RRD. Conclusion: In patients with macula-off rhegmatogenous retinal detachment, foveal avascular zone area in the deep capillary plexuses was enlarged and vascular density in the foveal deep capillary plexus was reduced, even after the retina was successfully reattached through a primary surgery.

Wide-field swept-source OCTA in the assessment of retinal microvasculature in early-stage diabetic retinopathy

BACKGROUND

To perform a quantitative analysis of retinal microvasculature in patients with early-stage diabetic retinopathy (DR) using wide-field swept-source optical coherence tomography angiography (SS-OCTA).  METHODS: One hundred nineteen eyes of 119 patents (67 eyes with no DR and 52 eyes with mild-moderate nonproliferative diabetic retinopathy (NPDR)) were enrolled in this observational and cross-sectional cohort study, and an age-matched group consisting of 39 eyes of 39 non-diabetic subjects were set as the control. Each participant underwent a full ophthalmic examination, including wide-field SS-OCTA imaging. On OCTA scans (12 mm * 12 mm), the mean perfusion area (PA) and vessel density (VD) were independently measured in all 16 Early Treatment Diabetic Retinopathy Study (ETDRS) sectors. Linear regression analyses were conducted to evaluate the influences of PA.

RESULTS

In the central ring, there were no significant differences in the average PA and VD among the groups. In the 3 mm radius, the PA and VD of the no DR and mild-moderate NPDR were significantly decreased compared with the control group in superior and inferior quadrants. In the wide-field scans (9 and 12 mm radius), there was no significant difference in average PA and VD between the groups in each sectors (p > 0.05). Regression analysis found that the effect of VD on PA was statistically different (b = 1.311, p < 0.001).

CONCLUSION

Wide-field OCTA imaging is useful for evaluating peripheral capillary perfusion in eyes with early-stage DR. Decrease in PA and VD was greater in the S3 and I3 sectors, and reductions in PA and VD were uneven in wide-filed sectors (9 and 12 mm radius).

Structural and functional retinal changes in patients with type 2 diabetes without diabetic retinopathy

OBJECTIVE

The characteristics of the early changes in preclinical diabetic retinopathy (DR) are poorly known. This study aimed to analyse the changes in the structure and function of the fundus in diabetic patients without diabetic retinopathy (NDR).

METHODS

This prospective study enrolled patients with type 2 diabetes and healthy controls from April to December 2020. Retinal sensitivity was measured by microperimetry. The peripapillary retinal nerve fibre layer (p-RNFL) thickness, macular retinal thickness, and retinal volume were measured by optical coherence tomography (OCT). The vessel density (VD) and perfusion density (PD) of the peripapillary area, as well as the foveal avascular zone (FAZ) area, FAZ perimeter, and FAZ circularity, were measured by optical coherence tomographic angiography (OCTA).

RESULTS

A total of 71 cases (100 eyes) were enrolled in the study, including 34 cases (51 eyes) in the NDR group and 37 cases (49 eyes) in the control group. The mean retinal sensitivity was lower in the NDR group than in the control group for all sectors (all p < .001). Compared with controls, the NDR group showed thinner p-RNFL in the T sector (76.24 ± 14.29 vs. 85.47 ± 19.66 µm, p = .035). The NDR group had a thinner retina in the N2 sector (304.55 ± 16.07 vs. 312.02 ± 12.30 µm, p = .010). The PD of DCP was lower in the N2 sector in the NDR group (44.92 ± 11.77 vs. 50.27 ± 6.37%, p = .044). The VD was higher in the NDR group in RPCP-S/N/I, and the PD was higher in the RPCP-S/N (all p < .05). The frequencies of perifoveal capillary drop-out, notched or punched out borders of the superficial FAZ, and loss of smooth contour were all higher in the NDR group (all p < .05).

CONCLUSION

The structure (p-RNFL thickness, VD, and PD) and function (retinal sensitivity) display some changes in diabetic patients even if they had not been found to have DR.Key messagesDecreased retinal sensitivity was observed in diabetic patients before the onset of diabetic retinopathy.Compared with the control group, we found the changes in vessel density or perfusion density in a certain area, whether in SCP, DCP, or RPCP in the NDR group.Before the onset of diabetic retinopathy, the structure and function of the retina in diabetic patients had changed.

Retinal vascular assessment in psoriatic patients with and without metabolic syndrome using optical coherence tomography angiography

To evaluate the retinal vasculature in psoriasis patients and detect if metabolic syndrome is an additional risk factor. This cross-sectional analytic study was carried out on 80 eyes of 80 subjects; 28 eyes with psoriasis only (PS group), 12 eyes with additional metabolic syndrome to psoriasis (PMS group) and 40 eyes healthy controls (HS). The retinal capillary plexuses were evaluated by OCTA. The disease activity was evaluated by the Psoriasis Area and Severity Index (PASI) score and extent. The superficial capillary plexus (SCP) vascular density was significantly lower in PS group than HS while in PMS it was significantly lower only in whole image and superior and temporal perifoveal areas (p-value = 0.020, 0.030, 0.001 respectively). The changes correlated with the disease duration. The vascular density of the deep capillary plexus (DCP) was significantly lower in both PS and PMS groups (p-value < 0.001). Psoriatic patients are at a higher risk of developing retinal vascular complications even without evident clinical ocular disease. It was noted that the presence of metabolic syndrome contributes as an additional risk factor in possible visual loss secondary to ischemic changes that are likely to start in the DCP and progress to involve all levels.

Evolution of Quantitative Optical Coherence Tomography Angiography Markers with Glycemic Control: A Pilot Study

Aim: We aimed to analyze changes in retinal microvascularization with intensive reduction of glycated hemoglobin A1c (HbA1c) in patients with poorly controlled diabetes using quantitative optical coherence tomography angiography (OCT-A) metrics. Method: This was a retrospective observational study in patients with uncontrolled diabetes admitted to the hospital for glycemic control. A second set of 15 healthy volunteers was included to serve as a control group. OCT-A was performed at inclusion and at 3 months to measure foveal avascular zone area (FAZA), vessel density (VD) of the superficial capillary plexus (SCP) and deep capillary plexus (DCP), acircularity index (AI), and fractal dimension (FD). Results: This analysis included 35 patients (35 eyes): 28 type-2 diabetics and 7 type-1 diabetics. Mean HbA1c was 13.1 ± 2.0% at inclusion and 7.0 ± 1.5% at 3 months. In the short period from inclusion to 3 months post-inclusion, patients showed significant decrease in VD−DCP (28.8% vs. 27.8%; p = 0.014), a significant increase in FAZA (0.300 mm2 vs. 0.310 mm2; p < 0.001), and a significant increase in AI (1.31 vs. 1.34; p < 0.01). Multivariate analysis found an increase in FAZA was correlated with baseline HbA1c level and age (R2 = 0.330), and a decrease in VD-DCP was correlated with HbA1c decrease and diabetes duration (R2 = 0.286). Conclusions: Rapid glycemic control in patients with uncontrolled diabetes led to possible short-term microvascular damage that correlated to both initial and decreased HbA1c.

Nomogram-based prediction of clinically significant macular edema in diabetes mellitus patients

AIMS

The aim of the study was to construct and validate a risk nomogram for clinically significant macular edema (CSME) prediction in diabetes mellitus (DM) patients using systemic variables.

METHODS

In this retrospective study, DM inpatients who underwent routine diabetic retinopathy screening were recruited and divided into training and validation sets according to their admission date. Ninety-three demographic and systemic variables were collected. The least absolute shrinkage and selection operator was used to select the predictive variables from the training set. The selected variables were used to construct the CSME prediction nomogram. Internal and external validations were performed. The C-index, calibration curve and decision curve analysis (DCA) were reported.

RESULTS

A total of 349 patients were divided into the training set (240, 68.77%) and the validation set (109, 31.23%). The presence of diabetic peripheral neuropathy (DPN) symptoms, uric acid, use of insulin only or not for treatment, insulin dosage, urinary protein grade and disease duration were chosen for the nomogram. The C-index of the prediction nomogram was 0.896, 0.878 and 0.837 in the training set, internal validation and external validation, respectively. The calibration curves of the nomogram showed good agreement between the predicted and actual outcomes. DCA demonstrated that the nomogram was clinically useful.

CONCLUSIONS

A nomogram with good performance for predicting CSME using systemic variables was developed. It suggested that DPN symptoms and renal function may be crucial risk factors for CSME. Moreover, this nomogram may be a convenient tool for non-ophthalmic specialists to rapidly recognize CSME in patients and to transfer them to ophthalmologists for early diagnosis and treatment.

Artificial Intelligence-Based Teleopthalmology Application for Diagnosis of Diabetics Retinopathy

Diabetic Retinopathy (DR) is one of the leading causes of blindness for people who have diabetes in the world. However, early detection of this disease can essentially decrease its effects on the patient. The recent breakthroughs in technologies, including the use of smart health systems based on Artificial intelligence, IoT and Blockchain are trying to improve the early diagnosis and treatment of diabetic retinopathy. In this study, we presented an AI-based smart teleopthalmology application for diagnosis of diabetic retinopathy. The app has the ability to facilitate the analyses of eye fundus images via deep learning from the Kaggle database using Tensor Flow mathematical library. The app would be useful in promoting mHealth and timely treatment of diabetic retinopathy by clinicians. With the AI-based application presented in this paper, patients can easily get supports and physicians and researchers can also mine or predict data on diabetic retinopathy and reports generated could assist doctors to determine the level of severity of the disease among the people.

Characteristics of macular morphology and microcirculation in diabetic macular edema patients with serous retinal detachment

BACKGROUND

To analyze and compare the characteristics of macular morphology and microcirculation in diabetic macular edema (DME) patients with and without macular serous retinal detachment (SRD).

METHODS

One hundred eyes in 81 patients diagnosed with the DME (the central macular thickness (CMT) of ≥ 300 μm) from March 2020 to November 2020 were selected. According to whether complicated with SRD, patients were divided into DME with SRD (60 eyes) and without SRD (40 eyes) groups. We analyzed the following parameters: CMT, central retinal thickness (CRT), subfoveal choroidal thickness (SFCT), number of hyperreflective foci (HF) in the complete retina, inner retina, outer retina, and subretinal space, the integrity of the ellipsoid zone (EZ) and external limiting membrane (ELM), the presence of disorganization of inner retinal layers (DRIL), foveal avascular zone (FAZ) area, and the vascular flow density of superficial capillary plexus (SCP), deep capillary plexus (DCP), and choriocapillaris.

RESULTS

(1) Compared to the group without SRD, the group with SRD had a greater CMT (P < 0.05) and a smaller CRT (P < 0.001); (2) The number of the HF in the complete retina, outer retina, and the subretinal space was larger in the group with SRD (P < 0.001); 3.The proportion of the EZ disruption (P < 0.05) and ELM disruption (P < 0.001) were higher in the group with SRD; 4. The SFCT (P < 0.05) and the vascular flow density of choriocapillaris (P < 0.05) were greater in the group with SRD; 5. There were no significant differences in the FAZ area and the vascular flow density of the DCP and SCP (P > 0.05); 6. The presence of the SRD was correlated with the integrity of the ELM, the number of HF in the complete retina, outer retina, and subretinal space (χ2 = 26.930, OR = 0.707, 0.263, 0.995, P < 0.001), as well as the SFCT (OR = 0.992, P < 0.05).

CONCLUSIONS

The results support the hypothesis that the presence of the ELM disruption, the larger number of the HF, and the thickening and hyperperfusion of the choroid may be involved in the pathogenesis of SRD in DME.

Retinal Neurovascular Changes in Patients With Ischemic Stroke Investigated by Optical Coherence Tomography Angiography

Background

To investigate retinal neurovascular structural changes in patients with ischemic stroke (IS) using optical coherence tomography angiography (OCTA).

Materials and Methods

The cross-sectional study was conducted in Guangdong Provincial People’s Hospital, China, consisting of 159 eyes from IS patients and 109 eyes from age-matched control subjects. Retinal microvascular parameters including the vessel density (VD) of the superficial capillary plexus (SCP), deep capillary plexus (DCP) and radial peripapillary capillary (RPC), and neural parameters such as ganglion cell complex thickness (GCCt) and retinal nerve fibre layer thickness (RNFLt) were measured by OCTA.

Results

The VD of SCP and DCP in the macular area were significantly reduced in IS patients compared to the control group (all p &lt; 0.001). The VD of RPC at the optic disc was also significantly reduced in IS patients (all p &lt; 0.05). IS patients showed reduced GCCt and RNFLt and increased GCC focal loss volume and global loss volume compared with the controls (all p &lt; 0.05). Among patients with IS, the parafovea SCP VD was positively correlated with GCCt (r = 0.346–0.408, all p &lt; 0.001) but not with DCP VD (all p &gt; 0.1). In the optic disc region, the whole image RPC VD was positively correlated with mean RNFLt (r = 0.467–0.548, all p &lt; 0.001).

Conclusion

Reduction of retinal VD, GCCt and RNFLt was observed in patients with IS. The parafovea SCP VD and RPC VD were positively correlated with GCCt and RNFLt, respectively.

Macular Vessel Density Measurement in Pediatric Renal and Liver Transplant

OBJECTIVES

Microcirculatory dysfunction is known to be associated with organ failure and increased mortality in transplant patients. Noninvasive monitorization of retinal structures of the eye could be a predictor for systemic microvasculature in these patients. Therefore, in this study we aimed to evaluate the retinal microvascular changes in pediatric patients who had undergone liver or renal transplant surgery, using optical coherence tomography angiography.

MATERIALS AND METHODS

The medical records of pediatric patients who had liver or renal transplant in the past 10 years were reviewed. The macular vessel density parameters were obtained by optical coherence tomography angiography (Avanti RTVue XR). The results were compared with the age-matched, sex-matched, and spherical equivalent-matched healthy participants (control group). The IBM SPSS (version 25.0) statistics program was used for data analysis.

RESULTS

We included 32 eyes of 16 liver transplant patients, 20 eyes of 10 renal transplant patients, and 64 eyes of 32 healthy participants (control group). Superficial macular whole image, superficial perifoveal, and deep foveal vessel densities were found to be lower in the liver transplant group compared with the healthy control group (P = .02, P = .01, and P = .01, respectively). Superficial foveal, deep macular whole image, deep foveal, and deep perifoveal vessel densities were found to be lower in the renal transplant group compared with the healthy control group (P = .03, P = .04, P = .01, and P = .02, respectively).

CONCLUSIONS

Macular vessel density measurements are affected in pediatric renal and liver transplant patients. In those patients, retinal optical coherence tomography and optical coherence tomography angiography measurements may provide a noninvasive window to the microcirculation.

Flow and geometrical alterations in retinal microvasculature correlated with the occurrence of diabetic retinopathy: evidence from a longitudinal study

PURPOSE

To assess the relationship between flow and geometric parameters in optical coherence tomography angiography (OCTA) images and the risk of incident diabetic retinopathy (DR).

METHODS

This prospective, observational cohort study recruited patients with type 2 diabetes without DR in Guangzhou, China and followed up annually. A commercially available OCTA device (DRI-OCT Triton; Topcon Inc., Tokyo, Japan) was used to obtain a variety of flow (foveal avascular zone [FAZ] area, vessel density [VD], vessel length density [VLD]) and geometric (fractal dimension [FD] and blood vessel tortuosity [BVT]) parameters in superficial capillary plexus (SCP) and deep capillary plexus (DCP). The odds ratio [OR] and its 95% confidential interval [CI] were calculated per 1-SD increase in each OCTA parameter.

RESULTS

Over a follow-up of one year, 182 of 1,698 participants (10.7%) developed incident DR. After adjusting for conventional risk factors and image quality score, the higher risk of DR onset was significantly associated with the reduced parafoveal VD of SCP (OR=0.81; 95% CI: 0.69, 0.96; P = 0.016), reduced parafoveal VLD of SCP (OR=0.73; 95% CI: 0.59, 0.90; P = 0.003), reduced FD of SCP (OR=0.73; 95% CI: 0.61, 0.87; P < 0.001), increased BVT of SCP (OR=1.39; 95% CI: 1.18, 1.64; P < 0.001) and increased BVT of DCP (OR=1.19; 95% CI: 1.01, 1.40; P = 0.033) .

CONCLUSION

Reduced vessel density and impaired vessel geometry posed higher susceptibility for DR onset in patients with type 2 diabetes, supporting the adoption of OCTA parameters as early monitoring indicators of the newly incident DR.

The Value of Optical Coherence Tomography Angiography (OCT-A) in Neurological Diseases

Optical coherence tomography angiography (OCT-A) was commercially introduced in 2014. OCT-A allows a fast, non-invasive, three-dimensional analysis of the retinal vasculature from the vitreoretinal interface to the choriocapillaris. The results can be evaluated separately in automated or custom-defined retinal layers. Since its introduction, OCT-A has also been used in patients with neurological diseases in order to find and characterize retinal biomarkers. Many neurological diseases have retinal manifestations, often preceding the key symptoms of the neurological disease. Anatomically and developmentally, the retina is a part of the brain. In contrast to the brain, the retina is easily accessible for imaging methods; moreover, retinal imaging is more cost-effective than brain imaging. In this review, the current knowledge about OCT-A findings and possible OCT-A biomarkers in neurological diseases is summarized and discussed regarding the value of OCT-A as a diagnostic tool in neurological diseases.

Retinal vascular impairment in Wolfram syndrome: an optical coherence tomography angiography study

To evaluate differences in macular and optic disc circulation in patients affected by Wolfram Syndrome (WS) employing optical coherence tomography-angiography (OCTA) imaging. In this retrospective study, 18 eyes from 10 WS patients, 16 eyes of 8 patients affected by type I diabetes and 17 eyes from 17 healthy controls were enrolled. All patients were imaged through OCT and OCTA and vascular parameters, as perfusion density (PD) and vessel length density (VLD) were measured. OCTA showed reduced PD in WS patients at the macular superficial capillary plexus (SCP, 27.8 ± 5.3%), deep vascular complex (DVC, 33.2 ± 1.9%) and optic nerve head (ONH, 21.2 ± 9.1%) compared to both diabetic patients (SCP 33.9 ± 1.9%, P < 0.0001; DVC 33.2 ± 0.7%, P = 1.0; ONH 33.9 ± 1.3, P < 0.0001) and healthy controls (SCP 31.6 ± 2.5, P = 0.002; DVC 34.0 ± 0.7%, P = 0.089; ONH 34.6 ± 0.8%, P < 0.0001). Similarly, VLD was lower in WS patients at the SCP (10.9 ± 2.7%) and ONH levels (7.5 ± 4.1%) compared to diabetic patients (SCP 13.8 ± 1.2%, P = 0.001; DVC 13.8 ± 0.2%, P < 0.0001; ONH 13.0 ± 0.7%, P =  < 0.0001), but higher in DVC (15.7 ± 1.2%, P < 0.0001). Furthermore, VLD was lower in WS patients in all the vascular parameters compared to controls (SCP 13.8 ± 1.5%, P < 0.0001; DVC 17.3 ± 0.6%, P < 0.0001; ONH 15.7 ± 0.5%, P < 0.0001). A significant microvasculature impairment in the macular SCP and ONH microvasculature was demonstrated in eyes affected by WS. Microvascular impairment may be considered a fundamental component of the neurodegenerative changes in WS.

Association of serum apolipoprotein B with retinal neurovascular structural alterations in patients with type 2 diabetes: an optical coherence tomography angiography study

PURPOSE

To investigate the association of serum apoB concentrations with retinal neurovascular structural alterations in type 2 diabetes patients without clinically visible retinopathy.

METHODS

Eyes with no clinically visible diabetic retinopathy (DR) from diabetic patients with or without dyslipidemia were included. Changes in retinal neural structures, including the ganglion cell layer (GCL) and peripapillary retinal nerve fiber layer (RNFL) thicknesses, and microvascular metrics, including macular vessel density (VD) and perfusion density (PD) of the superficial capillary plexus, were measured with optical coherence tomography angiography (OCTA). Correlations between inner retinal layer thickness and OCTA metrics were analyzed. The association of serum apoB and diabetic retinal neurovascular structures was identified with regression analysis.

RESULTS

A total of 148 eyes in the diabetes group (n = 74) and dyslipidemia group (n = 74) were enrolled. GCL and RNFL thicknesses in patients in the dyslipidemia group were significantly thinner than those in the diabetes group (all p < 0.025). The total area of the VD and PD in the dyslipidemia group was also decreased compared to that of the diabetes group (p < 0.05) and was found to correlate with GCL and RNFL (all p < 0.01) thicknesses in all diabetic patients. Serum apoB levels were positively related to low-density lipoprotein (LDL) and total cholesterol (TC). Moreover, the average GCL thickness was significantly associated with serum apoB levels (all p < 0.05).

CONCLUSIONS

GCL and RNFL thinning was significantly correlated with decreased retinal blood flow in diabetic patients with dyslipidemia. Strictly controlling serum lipids, especially apoB levels, might be an effective strategy for DR treatment.

Retinal Vascular Response to Hyperoxia in Patients with Diabetes Mellitus without Diabetic Retinopathy

Purpose

To evaluate the retinal vascular response to hyperoxia in patients with diabetes at the preclinical stage of diabetic retinopathy (DR) and to quantify the changes in comparison with normal subjects using optical coherence tomography angiography (OCTA).

Methods

In this prospective study, 40 eyes of 20 participants comprising 10 diabetic patients with no diabetic retinopathy (NDR) and 10 normal subjects were recruited. OCTA images were acquired in the resting position and were repeated after a hyperoxic challenge using a nasal mask connected to a reservoir bag supplying 100% oxygen at the rate of 15 L per minute for 5 minutes. The changes of mean parafoveal vessel density (VD) in the superficial capillary plexus (SCP) and deep capillary plexus (DCP), the foveal avascular zone (FAZ) size, and the outer retina flow index were compared between two conditions in each group and between the two study groups. The statistical significance of differences in the means was evaluated using Student's t-test for unpaired samples with consideration of the generalized estimating equations (GEE) for intereye correlation.

Results

At baseline, the mean parafoveal VD of SCP and DCP were significantly lower in the NDR participants compared to the healthy subjects (P < 0.001 and P = 0.006, respectively). After induction of the hyperoxic challenge in healthy participants, mean parafoveal VD reduced at both the SCP and DCP, but reached a statistical significance only in DCP (P = 0.006). However, following induction of hyperoxic challenge in patients with NDR, no significant decline was noticed in mean parafoveal VD of SCP and DCP. The degree of change in mean parafoveal VD of DCP was statistically significantly more pronounced in healthy subjects compared to the NDR group (P = 0.034). The change in FAZ size and the outer retina flow index were comparable between the two study groups.

Conclusion

Retinal capillary layers responded differently to hyperoxia-induced challenge, and in normal subjects, the autoregulatory mechanism was mostly effective in the parafoveal DCP. Retinal vascular reactivity was impaired in SCP and DCP at the preclinical stage of DR. OCTA as a noninvasive modality was able to quantify the retinal vascular response to the hyperoxic challenge.

Detection of the Microvascular Changes of Diabetic Retinopathy Progression Using Optical Coherence Tomography Angiography

Purpose

To investigate microvascular parameters that are related to the severity of diabetic retinopathy (DR) with optical coherence tomography angiography (OCTA).

Methods

In total, 105 eyes from 105 diabetic patients were recruited in this prospective cross-sectional study, including 37 eyes with no clinical signs of DR (NoDR), 43 eyes with nonproliferative diabetic retinopathy (NPDR), and 25 eyes with proliferative diabetic retinopathy (PDR). Angiogram images from the parafoveal superficial capillary plexus (SCP), the deep capillary plexus (DCP), and the radial peripapillary capillary plexus were analyzed, and metrics were compared among groups. Multivariate regression analysis was used to identify the best OCTA parameters that could distinguish DR severity among groups.

Results

Parafoveal vessel diameter index in the SCP and vessel density (VD) in the DCP showed the strongest correlation with the severity of DR (P < 0.01). Extrafoveal avascular area in the SCP was the parameter that could most distinguish NoDR from NPDR (P < 0.01) with sensitivity and specificity of 83.72% and 78.38%, respectively. VD in the DCP also was the most sensitive biomarker to distinguish NPDR from PDR (P < 0.01) with sensitivity and specificity of 84.00% and 79.07%, respectively.

Conclusions

The microvascular changes in the SCP and DCP in DR may have different characteristics that could be identified with specific OCTA parameters. OCTA serves as a promising technology to discriminate eyes with different severity of DR.

Translational Relevance

Our study investigated OCTA metrics and severity of DR. At different stages of DR, ophthalmologists may focus on specific OCTA parameters to predict the progression of retinopathy in individual patients.

Quantitative analysis of retinal vessel density and thickness changes in diabetes mellitus evaluated using optical coherence tomography angiography: a cross-sectional study

Background

Diabetic retinopathy is the most common microvascular complication of diabetes; however, early changes in retinal microvessels are difficult to detect clinically, and a patient’s vision may have begun to deteriorate by the time a problem is identified. Optical coherence tomography angiography (OCTA) is an innovative tool for observing capillaries in vivo. The aim of this study was to analyze retinal vessel density and thickness changes in patients with diabetes.

Methods

This was a retrospective, observational cross-sectional study. Between August 2018 and February 2019, we collected OCTA data from healthy participants and diabetics from the First Affiliated Hospital of Harbin Medical University. Analyzed their retinal vessel density and thickness changes.

Results

A total of 97 diabetic patients with diabetes at different severity stages of diabetic retinopathy and 85 controls were involved in the experiment. Diabetic patients exhibited significantly lower retinal VD (particularly in the deep vascular complexes), thickening of the neurosensory retina, and thinning of the retinal pigment epithelium compared with controls. In the control group, nondiabetic retinopathy group and mild diabetic retinopathy group, superficial VD was significantly correlated with retinal thickness (r = 0.3886, P < 0.0001; r = 0.3276, P = 0.0019; r = 0.4614, P = 0.0024, respectively).

Conclusions

Patients with diabetes exhibit ischemia of the retinal capillaries and morphologic changes in vivo prior to vision loss. Therefore, OCTA may be useful as a quantitative method for the early detection of diabetic retinopathy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-021-01988-2.

Quantitative Parameters from OCT Angiography in Patients with Diabetic Retinopathy and in Those with Only Peripheral Retinopathy Compared with Control Participants

Purpose

To describe the differences in a range of quantitative OCT angiography (OCTA) metrics across early stages of diabetic retinopathy (DR), providing robust effect estimates as well as sensitivity and specificity.

Design

Cross-sectional study with population-based sampling.

Participants

Four hundred forty-one eyes from 296 individuals: 328 control eyes (no diabetes mellitus [DM] and no DR), 55 eyes with DM and no DR, and 58 eyes with early nonproliferative DR.

Methods

Multimodal retinal imaging included color fundus photography, color Optomap ultra-widefield imaging, and spectral-domain OCT (Spectralis OCT2; Heidelberg Engineering GmbH) with the OCTA module. All images were graded for the presence and severity of DR features. OCTA images were assessed manually for inclusion based on quality. Binary OCTA metrics were assessed after 3-dimensional projection artifact removal including from the nerve fiber layer vascular plexus, superficial vascular plexus (SVC), and deep vascular plexus (DVC) by Early Treatment Diabetic Retinopathy Study (ETDRS) grid, foveal avascular zone (FAZ) area, FAZ minimum and maximum diameter, perimeter length, and circularity.

Main Outcome Measures

Diabetes mellitus and DR status and presence or absence of DR in the retinal periphery.

Results

The reduction in vessel densities in participants with DM and manifest DR compared with control participants tended to be twice that of those with DM, but no DR, compared with control participants. Some evidence of spatial heterogeneity in vessel reductions was found in those yet to develop DR, whereas those with manifest DR had significant reductions across the ETDRS grid. The FAZ perimeter and circularity were impacted most significantly by DM, and those with DR showed decreased multispectral fractal dimensions compared with control participants. Eyes with peripheral DR had reduced vessel density compared with those with DM and no DR only in the superior outer, temporal inner, and temporal outer regions in the DVC and SVC. The area under the receiver operating characteristic curve ranged between 0.48 and 0.73.

Conclusions

Significant differences in OCTA metrics can be found in those with DM before manifest DR using commercially available equipment with minimal image postprocessing. Although diagnostic performance was poor, these metrics may be useful for measuring change over time in clinical trials.