Stages Of Non-proliferative Diabetic Retinopathy Research Articles

Inner retinal oxygen delivery and metabolism in progressive stages of diabetic retinopathy

Previous studies have reported increased retinal venous oxygen saturation and decreased retinal blood flow and oxygen metabolism in non-proliferative diabetic retinopathy (NPDR). The current study aimed to determine alterations in both inner retinal oxygen delivery (DO2) and metabolism (MO2) in proliferative DR (PDR) as well as at stages of NPDR. A total of 123 subjects participated in the study and were categorized into five groups: non-diabetic control (N = 32), diabetic with no diabetic retinopathy (NDR, N = 34), mild NPDR (N = 31), moderate to severe NPDR (N = 17), or PDR (N = 9). Multi-modal imaging was performed to measure oxygen saturation and blood flow, which were used for derivation of DO2 and MO2. There were significant associations of groups with DO2 and MO2. DO2 was lower in PDR and not significantly different in NDR and NPDR stages as compared to the non-diabetic control group. MO2 was decreased in PDR and moderate to severe NPDR as compared to the control group, and not significantly reduced in NDR and mild NPDR. The findings demonstrate reductions in both DO2 and MO2 in PDR and MO2 in moderate to severe NPDR, suggesting their potential as biomarkers for monitoring progression and treatment of DR.

The Relationship Between Health Insurance Status and Diabetic Retinopathy Progression

ObjectiveTo determine if baseline diabetic retinopathy severity mediates the relationship between health insurance status and diabetic retinopathy progression. DesignRetrospective cohort study Subjects716 patients aged ≥18 years with a diagnosis of type 1 or 2 diabetes mellitus, and a diagnosis of non-proliferative diabetic retinopathy (NPDR) were identified from the electronic health record (EHR) of a tertiary academic center between 6/2012 and 2/2022. MethodsNPDR severity at baseline was the proposed mediator in the relationship between insurance status and PDR progression. Logistic regression was used to determine the association between insurance status and NPDR severity at baseline, and Cox proportional hazards regression was used to assess the association between insurance status and time to PDR progression. To analyze the mediation effect of NPDR severity at baseline, a counterfactual approach, which decomposes a total effect into a natural direct effect and a natural indirect effect was applied. Main Outcome MeasuresTime to progression from first NPDR diagnosis to first PDR diagnosis. ResultsOf the 716 patients, 581 (81%) had Medicare or private insurance, 107 (15%) had Medicaid, and 28 (4.0%) were uninsured at their baseline eye visit. Uninsured or Medicaid patients had a higher proportion of moderate or severe NPDR at their baseline eye visit, and a higher proportion of progression to PDR. After adjusting for confounders and NPDR severity at baseline, uninsured patients had significantly greater risk of progression to PDR compared to Medicare/private insurance patients (HR 2.63, 95% CI 1.10 – 6.25). Medicaid patients also had an increased risk of progression to PDR compared to Medicare/private insurance patients, although not statistically significant (HR 1.53, 95% CI 0.81 – 2.89). NPDR severity at baseline mediated 41% of the effect of insurance status (uninsured vs Medicare/private insurance) on PDR progression. ConclusionsUninsured patients were more likely to have an advanced stage of NPDR at their baseline eye visit and were at significantly greater risk of progression to PDR compared with Medicare or privately insured patients. Mediation analysis revealed that differences in baseline NPDR severity by insurance explained a significant proportion of the relationship between insurance status and diabetic retinopathy progression.

SUPPORT VECTOR MACHINE MODELS FOR DIABETIC RETINOPATHY DIAGNOSIS AND GRADING

This work applies five variants of the support vector machine to the classification of the various stages of nonproliferative diabetic retinopathy. Four hundred eye fundus images from the Messidor repository are preprocessed and thirteen features extracted. The features best suited as inputs for support vector machine classification are identified. Initially, binary classification of severe nonproliferative diabetic retinopathy alone versus a normal eye is performed, achieving an accuracy of 97.44% using the standard support vector machine with Gaussian kernel and when optimized for accuracy. When optimized for sensitivity, the twin bounded support vector machine achieves the highest sensitivity of 99.06%. Then multiclass grading into all four stages of nonproliferative diabetic retinopathy is performed. Best performance with regards to four performance metrics, namely accuracy, sensitivity, specificity, and precision is achieved with the twin bounded support vector machine variant, when one-versus-one decision configuration is used in combination with a novel decision strategy that includes accumulated distances from the decision hyperplanes in the decision algorithm. The results compare favorably with data published in the literature.

Neuro-vascular coupling and heart rate variability in patients with type II diabetes at different stages of diabetic retinopathy.

There is evidence that diabetes is accompanied by a break-down of functional hyperemia, an intrinsic mechanism of neural tissues to adapt blood flow to changing metabolic demands. However, to what extent functional hyperemia is altered in different stages of diabetic retinopathy (DR) in patients with type II diabetes is largely unknown. The current study set out to investigate flicker-induced retinal blood flow changes in patients with type II diabetes at different stages of DR. A total of 76 subjects were included in the present parallel-group study, of which 56 had diabetes with either no DR or different stages of non-proliferative DR (n = 29 no DR, 12 mild DR, 15 moderate to severe DR). In addition, 20 healthy subjects were included as controls. Retinal blood flow was assessed before and during visual stimulation using a combined measurement of retinal vessel calibers and blood velocity by the means of Doppler optical coherence tomography (OCT). To measure systemic autonomic nervous system function, heart rate variability (HRV) was assessed using a short-term orthostatic challenge test. In healthy controls, retinal blood flow increased by 40.4 ± 27.2% during flicker stimulation. Flicker responses in patients with DR were significantly decreased depending on the stage of the disease (no DR 37.7 ± 26.0%, mild DR 26.2 ± 28.2%, moderate to severe DR 22.3 ± 13.9%; p = 0.035, ANOVA). When assessing systemic autonomous neural function using HRV, normalized low frequency (LF) spectral power showed a significantly different response to the orthostatic maneuver in diabetic patients compared to healthy controls (p < 0.001). Our study indicates that flicker induced hyperemia is reduced in patients with DR compared to healthy subjects. Further, this impairment is more pronounced with increasing severity of DR. Further studies are needed to elucidate mechanisms behind the reduced hyperemic response in patients with type II diabetes. [https://clinicaltrials.gov/], identifier [NCT03 552562].

Retinal Oxygen Metabolism in Patients With Type 2 Diabetes and Different Stages of Diabetic Retinopathy.

The aim of this cross-sectional study was to assess retinal oxygen metabolism in patients with type 2 diabetes and different stages of nonproliferative diabetic retinopathy (DR) (n = 67) compared with healthy control subjects (n = 20). Thirty-four patients had no DR, 15 had mild DR, and 18 had moderate to severe DR. Retinal oxygen saturation in arteries and veins was measured using the oxygen module of a retinal vessel analyzer. Total retinal blood flow (TRBF) was measured using a custom-built Doppler optical coherence tomography system. Retinal oxygen extraction was calculated from retinal oxygen saturation and TRBF. Arteriovenous difference in oxygen saturation was highest in healthy subjects (34.9 ± 7.5%), followed by patients with no DR (32.5 ± 6.3%) and moderate to severe DR (30.3 ± 6.5%). The lowest values were found in patients with mild DR (27.3 ± 8.0%, P = 0.010 vs. healthy subjects). TRBF tended to be higher in patients with no DR (40.1 ± 9.2 μL/min) and mild DR (41.8 ± 15.0 μL/min) than in healthy subjects (37.2 ± 5.7 μL/min) and patients with moderate to severe DR (34.6 ± 10.4 μL/min). Retinal oxygen extraction was the highest in healthy subjects (2.24 ± 0.57 μL O2/min), followed by patients with no DR (2.14 ± 0.6 μL O2/min), mild DR (1.90 ± 0.77 μL O2/min), and moderate to severe DR (1.78 ± 0.57 μL O2/min, P = 0.040 vs. healthy subjects). These results indicate that retinal oxygen metabolism is altered in patients with type 2 diabetes. Furthermore, retinal oxygen extraction decreases with increasing severity of DR.

"The Use of Calcium Dobesilate in the Treatment of the Early Stage of Non-Proliferative Diabetic Retinopathy"

"The Use of Calcium Dobesilate in the Treatment of the Early Stage of Non-Proliferative Diabetic Retinopathy"

"The Use of Calcium Dobesilate in the Treatment of the Early Stage of Non-Proliferative Diabetic Retinopathy"

Urmanova FM1* and Bakhritdinova FA2 Author Affiliations 1Head of Ophthalmology Department of the Multidisciplinary Clinic of the Tashkent Medical Academy, Uzbekistan 2Professor of the Department of Ophthalmology of the Tashkent Medical Academy, Uzbekistan Received: March 07, 2022 | Published: March 18, 2022 Corresponding author: Urmanova Firuza Makhkamovna, Candidate of Medical Sciences, Head of Ophthalmology Department of the Multidisciplinary Clinic of the Tashkent Medical Academy, Republic of Uzbekistan, 100047, Tashkent, Yashnabad district, ul. Machtumkuli, 103, Uzbekistan DOI: 10.26717/BJSTR.2022.42.006797

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Порушення агрегації тромбоцитів як чинник розвитку діабетичної макулопатії та діабетичного макулярного набряку у хворих на непроліферативну діабетичну ретинопатію при цукровому діабеті 2-го типу

Актуальність. Аналіз сучасних даних дає можливість висунути припущення, що патогенетичні чинники цукрового діабету (ЦД) можуть провокувати проагрегантний статус тромбоцитів (Тц) та викликати порушення мікроциркуляції в оболонках ока і розвиток діабетичної макулопатії (ДМП) та діабетичного макулярного набряку (ДМН). Мета дослідження — проаналізувати порушення агрегації Тц при ДМН та ДМП за умов непроліферативної діабетичної ретинопатії (НПДР) при ЦД 2-го типу. Матеріали та методи. Дослідження включало 32 хворих (32 ока) із ЦД 2-го типу, у яких за класифікацією ETDRS виявлена легка (14 хворих, 14 очей) і помірна (18 хворих, 18 очей) стадії НПДР. Для дослідження Тц in vitro використовували аденозиндифосфат (АДФ), адреналін, ангіотензин-2 (Анг-2), фактор активації тромбоцитів (ФАТ) і колаген. Оцінку агрегації Тц проводили турбидиметричним методом на аналізаторі Chronolog (США). Результати. У пацієнтів з ДМП при помірній стадії НПДР виявлена більша реактивність Тц до Анг-2, ФАТ і адреналіну, ніж при легкій стадії (p &lt; 0,01). Даний феномен відбивав підвищення агрегації Тц внаслідок порушень симпатоадреналової та ренін-ангіотензинової систем та зростання тяжкості запалення. Гіперреактивність Тц до Анг-2 була причиною розвитку ДМН у хворих з ДМП при помірній стадії НПДР. Висновки. Патогенетичні чинники ЦД можуть провокувати проагрегантний статус Тц і тим самим викликати порушення мікроциркуляції в оболонках ока, що супроводжується розвитком ДМП і ДМН.

Optical Coherence Tomography Angiography Metrics Monitor Severity Progression of Diabetic Retinopathy-3-Year Longitudinal Study.

: BackgroundTo examine retinal vessel closure metrics and neurodegenerative changes occurring in the initial stages of nonproliferative diabetic retinopathy (NPDR) and severity progression in a three-year period. Methods: Three-year prospective longitudinal observational cohort of individuals with type 2 diabetes (T2D), one eye per person, using spectral domain-optical coherence tomography (SD-OCT) and OCT-Angiography (OCTA). Eyes were examined four times with one-year intervals. OCTA vessel density maps of the retina were used to quantify vessel closure. Thickness of the ganglion cell + inner plexiform layer (GCL + IPL) was examined to identify retinal neurodegenerative changes. Diabetic retinopathy ETDRS classification was performed using the seven-field ETDRS protocol. Results: A total of 78 eyes/patients, aged 52 to 80 years, with T2D and ETDRS grades from 10 to 47 were followed for 3 years with annual examinations. A progressive increase in retinal vessel closure was observed. Vessel density (VD) showed higher decreases with retinopathy worsening demonstrated by step-changes in ETDRS severity scale (p < 0.001). No clear correlation was observed between neurodegenerative changes and retinopathy progression. Conclusions: Retinal vessel closure in NPDR correlates with DR severity progression. Our findings provide supporting evidence that OCTA metrics of vessel closure may be used as a surrogate for DR severity progression.

Association of glycation markers with the progression of the initial stages of diabetic non-proliferative retinopathy in type 2 diabetes mellitus

Relevance. In the development and progression of non-proliferative diabetic retinopathy (NPDR) in type 2 diabetes mellitus (DM2), an important role belongs to the activity of the protein glycation process and the formation of advanced glycation end products (AGE).Objective: To link glycation markers carboxymethyl lysine (AGE-CML) and circulating AGE receptor (sRAGE) to the progression of early-stage of nonproliferative diabetic retinopathy in patients with type 2 diabetes.Material and methods. 91 patients (182 eyes) with diabetes mellitus aged 42 to 80 years were examined. The control group included 25 people of the appropriate age. At the time of the initial examination and 1 year later, the NPDR stage was established according to the modified ETDRS system of clinical signs Airlie House. The content of glycation markers was determined by enzyme-linked immunosorbent assay in blood plasma. MedStat and MedCalc v.15.1 (MedCalc Software bvba) software packages were used for statistical research.Results. The initial manifestations of diabetic retinal lesions occurred in 27.5% of patients, began after 7.16 ± 1.11 years and were accompanied by higher glycemia. The content of AGE-CML in diabetes mellitus was significantly increased compared to the control, which was more pronounced in the presence of initial retinal changes - was 1.3 times higher than in patients without such changes (p = 0.015). The content of sRAGE decreased several times, which was also associated with the presence of diabetic retinal changes - in their presence it was 2.2 times lower (p &lt;0.001). The content of AGE-CML was significantly higher (1.5 times; p &lt;0.001) in the presence of NPDR progression during 1 year of observation than without it. The content of sRAGE in the presence of progression was 1.6 times (p &lt;0.001) lower. Conclusion. Thus, accumulation of blood AGE-CML and sRAGE reduction is connected with the occurrence and progression of NPDR.Key words: nonproliferative diabetic retinopathy, type 2 diabetes mellitus, Advanced Glicated End Products, AGE-CML, sRAGE

Non‐invasive structural and metabolic retinal markers of disease activity in non‐proliferative diabetic retinopathy

Metabolic and structural microvascular retinal alterations are essential components in diabetic retinopathy (DR). The present study aimed to measure changes at different stages of non-proliferative DR (NPDR) and to explore interactions of imaging-based metrics. This cross-sectional, cohort study included 139 eyes from 80 diabetic patients. Each patient underwent dilated fundal examinations including colour fundus photography, retinal oximetry and optical coherence tomography angiography (OCTA), analysed by semi-automated and automated software. Diabetic retinopathy (DR) severity was classified according to the International Clinical Diabetic Retinopathy (ICDR) Severity Scale, ranging from no DR to severe NPDR (level 0-3). Retinal metabolism was evaluated by oximetry as retinal arteriolar (raSatO2 ) and venular oxygen saturation (rvSatO2 ), and macular microvascular structure was measured by OCTA as the area of foveal avascular zone (FAZ), vessel density (VD), vessel diameter index (VDI), FAZ circularity and fractal dimension (FD) in the superficial and deep retinal capillary plexus. A trend for increasing rvSatO2 was found with increasing DR severity (51.3%, 53.3%, 54.2%, 59.8%, p=0.02). Increasing severity of DR associated with decreasing FD in the superficial and deep plexus (p<0.001 and p=0.014), and in the superficial plexus decreasing VD (p<0.001), increasing VDI (p=0.003) and decreasing FAZ circularity (p=0.006). A few interactions were identified between raSatO2 , rvSatO2 and VDI, but only in the deep capillary plexus (p<0.01 and p<0.01). Alterations of the venular retinal vascular oxygen saturation and microvascular structural abnormities were found continuously throughout the DR-spectrum. Given the sparse correlations between metabolic and structural abnormalities, it seems that these occur independently in DR.

Swept-source OCTA quantification of capillary closure predicts ETDRS severity staging of NPDR

PurposeTo test whether a single or composite set of parameters evaluated with optical coherence tomography angiography (OCTA), representing retinal capillary closure, can predict non-proliferative diabetic retinopathy (NPDR) staging according to...

A Classification Approach Using Fuzzy Inference System for Non-Proliferative Diabetic Retinopathy

This paper proposes a classification technique using fuzzy inference system (FIS) for non-proliferative diabetic retinopathy (NPDR). The input variables to FIS are the extracted features from the pathologies of NPDR. Abnormalities like exudates and microaneuryms are segmented for feature extraction. The pathological aspects of NPDR leads to fuzzy if-then rules that effectively handles the fuzziness present in some of the features. The role of FIS in NPDR classification replaces the training phase in learning based classification methods. The performance of the proposed fuzzy approach is analyzed for stages of NPDR and diabetic retinopathy classification on various databases. The accuracy of 98.2% is observed for NPDR classification in Messidor database.

QUANTITATIVE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY FEATURES FOR OBJECTIVE CLASSIFICATION AND STAGING OF DIABETIC RETINOPATHY.

This study aims to characterize quantitative optical coherence tomography angiography (OCTA) features of nonproliferative diabetic retinopathy (NPDR) and to validate them for computer-aided NPDR staging. One hundred and twenty OCTA images from 60 NPDR (mild, moderate, and severe stages) patients and 40 images from 20 control subjects were used for this study conducted in a tertiary, subspecialty, academic practice. Both eyes were photographed and all the OCTAs were 6 mm × 6 mm macular scans. Six quantitative features, that is, blood vessel tortuosity, blood vascular caliber, vessel perimeter index, blood vessel density, foveal avascular zone area, and foveal avascular zone contour irregularity (FAZ-CI) were derived from each OCTA image. A support vector machine classification model was trained and tested for computer-aided classification of NPDR stages. Sensitivity, specificity, and accuracy were used as performance metrics of computer-aided classification, and receiver operation characteristics curve was plotted to measure the sensitivity-specificity tradeoff of the classification algorithm. Among 6 individual OCTA features, blood vessel density shows the best classification accuracies, 93.89% and 90.89% for control versus disease and control versus mild NPDR, respectively. Combined feature classification achieved improved accuracies, 94.41% and 92.96%, respectively. Moreover, the temporal-perifoveal region was the most sensitive region for early detection of DR. For multiclass classification, support vector machine algorithm achieved 84% accuracy. Blood vessel density was observed as the most sensitive feature, and temporal-perifoveal region was the most sensitive region for early detection of DR. Quantitative OCTA analysis enabled computer-aided identification and staging of NPDR.

Macular OCT-angiography parameters to predict the clinical stage of nonproliferative diabetic retinopathy: an exploratory analysis.

To test whether a single or a composite set of macular vascular density parameters, evaluated with optical coherence tomography angiography (OCTA), are able to predict nonproliferative diabetic retinopathy (NPDR) staging according to the gold-standard ETDRS-grading scheme. Prospectively defined, cross-sectional study in which macular structural and vascular parameters of diabetic eyes with nonproliferative DR (up to ETDRS Level 53) were evaluated with OCTA (Avanti RTVue-XR 100, Optovue Inc, Fremont, CA). Seven-field photographs of the fundus were taken for DR staging according to the ETDRS-grading scheme. The vessel density in the superficial and deep capillary plexus (SCP and DCP, respectively), as well as in the choriocapillaris (CC), were calculated using automated software. Univariate and multivariate ordered logistic regression models were used in the analysis. P < 0.05 was considered statistically significant. We included 101 eyes from 56 subjects (mean (SD) age 62.64 (11.74) years; 57.4% were male). On univariate analysis, several OCTA parameters were found to be associated with higher ETDRS level (parafoveal SCP density: OR = 0.87 (95% CI 0.76-0.99), p = 0.039; parafoveal DCP density: OR = 0.79 (95% CI 0.72-0.87), p < 0.001; CC density: OR = 0.89 (95% CI 0.80-0.99)), p = 0.036). In the final model, while also adjusting for relevant clinical features, only parafoveal vessel density in the DCP remained as a significant predictor of NPDR ETDRS level (OR = 0.54 (95% CI 0.32-0.92), p = 0.024). Our results suggest that parafoveal vessel density in the DCP is the parameter most robustly associated with ETDRS level. OCTA analysis may provide objective imaging biomarkers to monitor NPDR clinical progression.

Retinopathy severity correlates with RANTES concentrations and CCR 5-positive microvesicles in diabetes.

RANTES regulates leukocyte recruitment to areas affected by the inflammatory process. Microvesicles (MVs) belong to a subpopulation of extracellular vesicles and show proangiogenic potential by transferring bioactive molecules to target cells. the aim of this study was to determine the relationship between circulating proangiogenic factors (MVs and RANTES) and diabetes complications in patients with different severities of diabetic retinopathy (DR). CCR5 (CD195) receptors transported by annexin V-labeled MVs were also investigated. Diabetic patients (n = 61), among whom 35 had confirmed DR classified according to guidelines, and controls (n = 25) were included. MVs were isolated by centrifugation and analyzed using flow cytometry, RANTES was assessed by ELISA. the study group differed from the control group with respect to BMI, age, heart rate and systolic blood pressure. Additionally, glucose and creatinine concentrations were significantly increased: 5.30 [5.09-5.62] vs. 9.38 [7.48-11.55] (p <0.0001) mmol/l and 74.59 [64-84] vs. 89.00 [77.11-105.44] μmol/l (p = 0.0005), respectively. RANTES concentrations were significantly increased in diabetic patients compared to those of controls (15.5 (9.7-18.1) vs. 8.9 (0.9-14.6) μg/ml (p = 0.011)), and RANTES concentration significantly increased with respect to nonproliferative DR progression. Moreover, the number of CCR5-positive MVs was significantly increased in patients with heavy nonproliferative diabetic retinopathy (HNPDR) compared to those with so nonproliferative DR (SNPDR): 1178 [836-2254] vs. 394 [275-799] counts/μl. Correlation of RANTES concentrations with the stage of nonproliferative DR and the statistically significant dependence of CCR5-positive MVs with disease progression suggest that MVs and RANTES can be considered new biomarkers.

Loss to Follow-up After Intravitreal Anti–Vascular Endothelial Growth Factor Injections in Patients with Diabetic Macular Edema

To determine the rate of loss to follow-up (LTFU) and associated risk factors in patients with nonproliferative diabetic retinopathy (NPDR) who had diabetic macular edema (DME) and were receiving intravitreal anti-vascular endothelial growth factor (VEGF) injections. Retrospective cohort study. A total of 2595 NPDR patients with DME who received at least one anti-VEGF injection at a single large retina practice from January 1, 2012, to January 1,2017. A retrospective review based on billing codes was performed. LTFU was defined as no subsequent office visits within 12 months after an intravitreal injection. Patient demographics and clinical features were evaluated, and logistic regression was used to identify independent predictors for LTFU. LTFU rates and potential risk factors. LTFU was found in 413 (25.3%) of 1632 patients. Examining LTFU by racial groups, 21.3% identified themselves as white, 29.1% as black, 30.6% as Asian, and 35.0% as Hispanic (P < 0.001). A difference in LTFU was also found based on average adjusted gross income (AGI) (P < 0.001) and NPDR stage (P= 0.04). In the multivariate model, factors associated with LTFU included Hispanic (odds ratio [OR] 1.66), American Indian, Pacific Islander, multiple races (OR 2.60), and unknown race (OR 1.59) compared with those who were white. Additional factors included those with an average AGI of $50000 to $75000 (OR 1.37) and <$50000 (OR 1.88) compared with those with an average AGI > $75000. Based on subgroup analysis of patients with available visual acuity data, a significant association was found between decreasing baseline vision and LTFU (P < 0.001). Approximately 1 in 4 patients with NPDR who had DME had no follow-up visit for at least 1 year after an anti-VEGF injection. Given the importance of ongoing therapy, these real-world findings may help identify at-risk groups for noncompliance with care.

Assessment of capillary dropout in the superficial retinal capillary plexus by optical coherence tomography angiography in the early stage of diabetic retinopathy

BackgroundTo assess capillary dropout in the superficial retinal capillary plexus (SCP) by optical coherence tomography angiography (OCTA) in the early stage of diabetic retinopathy (DR).MethodsThis study was a cross-sectional observational study. Patients that underwent OCTA examinations in our hospital between November 2015 and May 2016 were included in the study. The subjects were divided into two groups: A) normal controls (41 eyes of 41 subjects) and B) the DR patients (49 eyes of 49 patients with mild non-proliferative DR (NPDR)). The retinal thickness and SCP vessel density were analyzed using built-in software in nine sections of the macular area; whole scan area; fovea; parafovea; and sub-sections of the parafovea, superior-hemi, inferior-hemi, temporal, superior, nasal, and inferior. The correlation between vessel density and retinal thickness was also analyzed.ResultsThe SCP density was significantly lower (P < 0.05) in mild NPDR patients than in normal controls in all areas, with the exception of the fovea (P > 0.05). In the parafovea, superior-hemi, inferior-hemi, temporal, and nasal sectors of group B, the SCP density was negatively correlated with the corresponding retinal thickness (P < 0.05). Specifically, as the SCP density decreased, retinal thickness increased.ConclusionsIn the early stage of NPDR, retinal capillary dropout and retinal thickness changes can be clearly captured and analyzed by OCTA. The results confirm a negative correlation between vessel density and retinal thickness in diabetic patients. This noninvasive technique could be applied for DR detection and monitoring. Further study with a larger sample size is warranted.

QUANTIFICATION OF RETINAL VESSEL TORTUOSITY IN DIABETIC RETINOPATHY USING OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY.

To investigate the association of vessel tortuosity with severity of diabetic retinopathy (DR) using optical coherence tomography angiography. We retrospectively analyzed 30 healthy eyes and 121 eyes of diabetic subjects with no DR, mild nonproliferative DR (NPDR), moderate to severe NPDR and proliferative DR (PDR). Binarized images were used to quantify the vessel tortuosity, vessel density, foveal avascular zone (FAZ) area, and FAZ acircularity. The vessels were divided vertically as superficial retinal layer and deep retinal layer, and horizontally as circular areas with 3 mm and 1.5 mm diameters. Analysis of variance was performed for multiple comparisons. Correlation analysis evaluated the association between the quantified parameters. Compared with healthy eyes, vessel tortuosity increased as DR severity was more in NPDR, but decreased in PDR (P = 0.033). The decrease in vessel density and the increase in both FAZ area and FAZ acircularity were consistent, while DR approached PDR. Among all parameters, statistically significant difference between no DR and mild NPDR was observed only in vessel tortuosity, especially within the 1.5 mm area of superficial retinal layer (P = 0.011). Correlations of vessel tortuosity with FAZ area and acircularity were confined to the 3 mm and 1.5 mm areas of superficial retinal layer (r = -0.185, P = 0.023 for FAZ area; r = 0.268, P = 0.001 for FAZ acircularity), while vessel density strongly correlated with FAZ parameters in the superficial retinal layer and deep retinal layer. Vessel tortuosity increased as the stage of NPDR was more severe, but decreased in PDR. The vessel tortuosity determined using optical coherence tomography angiography might be a useful parameter indicating the progression to PDR, circumventing the risk from invasive conventional angiography.