scholarly journals Exploratory study of non-invasive, high-resolution functional macular imaging in subjects with diabetic retinopathy

2021 ◽  
Vol 14 (1) ◽  
pp. 57-63
Author(s):  
Thalmon R Campagnoli ◽  
◽  
Jing Tian ◽  
Delia Cabrera DeBuc ◽  
William E. Smiddy ◽  
...  
Keyword(s):  
Blood Flow ◽  
Diabetic Retinopathy ◽  
High Resolution ◽  
Functional Imaging ◽  
Case Series ◽  
Diabetic Patients ◽  
Capillary Perfusion ◽  
Imaging Device ◽  
Non Invasive ◽  
Retinal Microvasculature

AIM: To evaluate a high-resolution functional imaging device that yields quantitative data regarding macular blood flow and capillary network features in eyes with diabetic retinopathy (DR). METHODS: Prospective, cross-sectional comparative case-series in which blood flow velocities (BFVs) and non-invasive capillary perfusion maps (nCPMs) in macular vessels were measured in patients with DR and in healthy controls using the Retinal Functional Imager (RFI) device. RESULTS: A total of 27 eyes of 21 subjects were studied [9 eyes nonproliferative diabetic retinopathy (NPDR), 9 eyes proliferative diabetic retinopathy (PDR) and 9 controls]. All diabetic patients were type 2. All patients with NPDR and 5 eyes with PDR also had diabetic macular edema (DME). The NPDR group included eyes with severe (n=3) and moderate NPDR (n=6), and were symptomatic. A significant decrease in venular BFVs was observed in the macular region of PDR eyes when compared to controls (2.61±0.6 mm/s and 2.92±0.72 mm/s in PDR and controls, respectively, P=0.019) as well as PDR eyes with DME compared to NPDR eyes (2.36±0.51 mm/s and 2.94±1.09 mm/s in PDR with DME and NPDR, respectively, P=0.01). CONCLUSION: The RFI, a non-invasive imaging tool, provides high-resolution functional imaging of the retinal microvasculature and quantitative measurement of BFVs in visually impaired DR patients. The isolated diminish venular BFVs in PDR eyes compared to healthy eyes and PDR eyes with DME in comparison to NPDR eyes may indicate the possibility of more retinal vein compromise than suspected in advanced DR.

Review of Various Tasks Performed in the Preprocessing Phase of a Diabetic Retinopathy Diagnosis System

2020 ◽  
Vol 16 (4) ◽  
pp. 397-426
Author(s):  
Muhammad Nadeem Ashraf ◽  
Muhammad Hussain ◽  
Zulfiqar Habib
Keyword(s):  
Diabetic Retinopathy ◽  
Blood Vessels ◽  
Early Stage ◽  
Spherical Shape ◽  
Cost Effective ◽  
Lesion Detection ◽  
Diabetic Patients ◽  
Cad System ◽  
Non Invasive ◽  
Optic Discs

Diabetic Retinopathy (DR) is a major cause of blindness in diabetic patients. The increasing population of diabetic patients and difficulty to diagnose it at an early stage are limiting the screening capabilities of manual diagnosis by ophthalmologists. Color fundus images are widely used to detect DR lesions due to their comfortable, cost-effective and non-invasive acquisition procedure. Computer Aided Diagnosis (CAD) of DR based on these images can assist ophthalmologists and help in saving many sight years of diabetic patients. In a CAD system, preprocessing is a crucial phase, which significantly affects its performance. Commonly used preprocessing operations are the enhancement of poor contrast, balancing the illumination imbalance due to the spherical shape of a retina, noise reduction, image resizing to support multi-resolution, color normalization, extraction of a field of view (FOV), etc. Also, the presence of blood vessels and optic discs makes the lesion detection more challenging because these two artifacts exhibit specific attributes, which are similar to those of DR lesions. Preprocessing operations can be broadly divided into three categories: 1) fixing the native defects, 2) segmentation of blood vessels, and 3) localization and segmentation of optic discs. This paper presents a review of the state-of-the-art preprocessing techniques related to three categories of operations, highlighting their significant aspects and limitations. The survey is concluded with the most effective preprocessing methods, which have been shown to improve the accuracy and efficiency of the CAD systems.

Association of systemic cardio-vasculature status with retinal vascular endothelium in diabetes

2020 ◽  
Vol 1 (1) ◽  
pp. 52-57
Author(s):  
Galina Dimitrova ◽  
Keyword(s):  
Blood Flow ◽  
Diabetic Retinopathy ◽  
Optic Nerve ◽  
Arterial Stiffness ◽  
Vascular Endothelium ◽  
Lamina Cribrosa ◽  
Central Retinal Artery ◽  
Diabetic Patients ◽  
Retinal Artery ◽  
Central Retinal Vein

The relationship between diabetic retinopathy and macro-vascular complications in diabetes suggests a pathogenic association between these conditions. Vascular endothelium has been identified as a main site of blood vessel injury in diabetes. Diabetic retinopathy is associated with systemic arterial stiffness and altered vascular endothelium function and structure. Retinal vasculature endothelium at the macula, arterio-venous crossings, and in the optic nerve at the lamina cribrosa region is reported to differ from the endothelium in the rest of the retinal blood vessels. The central retinal artery and vein are in close proximity in the optic nerve where they share a common adventitia; thus, increased arterial wall stiffness and thickness may affect blood flow in the neighboring central retinal vein in this region. Moreover, increased arterial stiffness in small arterial beds is associated with retinal venular widening; it suggests the possibility of central retinal artery compressing the central retinal vein at the lamina cribrosa, thereby compromising venular outflow in the retina of diabetic patients. Altered blood flow in the central retinal vein in the postlaminar region has been detected in patients who experience progression of diabetic retinopathy. Increased hydrostatic pressure in the central retinal vein may play a major role in the pathogenesis of diabetic retinopathy. The aim of this review article is to emphasize this pathogenetic mechanism that has often been overlooked.

scholarly journals Retinal functional imager (RFI): Non-invasive functional imaging of the retina

2013 ◽  
Vol 5 (2) ◽  
pp. 250-257 ◽  
Author(s):  
Sunil Ganekal
Keyword(s):  
Functional Imaging ◽  
Structural Changes ◽  
Imaging System ◽  
Retinal Blood Flow ◽  
Capillary Perfusion ◽  
Functional Changes ◽  
Non Invasive ◽  
Retinal Disorders ◽  
Retinal Blood Flow Velocity ◽  
Perfusion Maps

Retinal functional imager (RFI) is a unique non-invasive functional imaging system with novel capabilities for visualizing the retina. The objective of this review was to show the utility of non-invasive functional imaging in various disorders. Electronic literature search was carried out using the websites www.pubmed.gov and www.google.com. The search words were retinal functional imager and non-invasive retinal imaging used in combination. The articles published or translated into English were studied. The RFI directly measures hemodynamic parameters such as retinal blood-flow velocity, oximetric state, metabolic responses to photic activation and generates capillary perfusion maps (CPM) that provides retinal vasculature detail similar to flourescein angiography. All of these parameters stand in a direct relationship to the function and therefore the health of the retina, and are known to be degraded in the course of retinal diseases. Detecting changes in retinal function aid early diagnosis and treatment as functional changes often precede structural changes in many retinal disorders. Nepal J Ophthalmol 2013; 5(10): 250-257 DOI: http://dx.doi.org/10.3126/nepjoph.v5i2.8738

scholarly journals Automated segmentation and fractal analysis of high-resolution non-invasive capillary perfusion maps of the human retina

2013 ◽  
Vol 89 ◽  
pp. 172-175 ◽  
Author(s):  
Hong Jiang ◽  
Delia Cabrera DeBuc ◽  
Tatjana Rundek ◽  
Byron L. Lam ◽  
Clinton B. Wright ◽  
...  
Keyword(s):  
High Resolution ◽  
Fractal Analysis ◽  
Automated Segmentation ◽  
Human Retina ◽  
Capillary Perfusion ◽  
Non Invasive ◽  
Perfusion Maps

scholarly journals Faulty homocysteine recycling in diabetic retinopathy

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Renu A. Kowluru ◽  
Ghulam Mohammad ◽  
Nikhil Sahajpal
Keyword(s):  
Dna Methylation ◽  
Diabetic Retinopathy ◽  
Methylenetetrahydrofolate Reductase ◽  
Epigenetic Modification ◽  
Mitochondrial Dynamics ◽  
Methylation Status ◽  
Mitochondrial Damage ◽  
Diabetic Patients ◽  
Retinal Microvasculature ◽  
Increased Risk

Abstract Background Although hyperglycemia is the main instigator in the development of diabetic retinopathy, elevated circulating levels of a non-protein amino acid, homocysteine, are also associated with an increased risk of retinopathy. Homocysteine is recycled back to methionine by methylenetetrahydrofolate reductase (MTHFR) and/or transsulfurated by cystathionine β-synthase (CBS) to form cysteine. CBS and other transsulfuration enzyme cystathionine-γ-lyase (CSE), through desulfuration, generates H2S. Methionine cycle also regulates DNA methylation, an epigenetic modification associated with the gene suppression. The aim of this study was to investigate homocysteine and its metabolism in diabetic retinopathy. Methods Homocysteine and H2S levels were analyzed in the retina, and CBS, CSE and MTHFR in the retinal microvasculature from human donors with established diabetic retinopathy. Mitochondrial damage was evaluated in retinal microvessels by quantifying enzymes responsible for maintaining mitochondrial dynamics (fission-fusion-mitophagy). DNA methylation status of CBS and MTHFR promoters was examined using methylated DNA immunoprecipitation technique. The direct effect of homocysteine on mitochondrial damage was confirmed in human retinal endothelial cells (HRECs) incubated with 100 μM L-homocysteine. Results Compared to age-matched nondiabetic control human donors, retina from donors with established diabetic retinopathy had ~ 3-fold higher homocysteine levels and ~ 50% lower H2S levels. The enzymes important for both transsulfuration and remethylation of homocysteine including CBS, CSE and MTHFR, were 40–60% lower in the retinal microvasculature from diabetic retinopathy donors. While the mitochondrial fission protein, dynamin related protein 1, and mitophagy markers optineurin and microtubule-associated protein 1A/1B-light chain 3 (LC3), were upregulated, the fusion protein mitofusin 2 was downregulated. In the same retinal microvessel preparations from donors with diabetic retinopathy, DNA at the promoters of CBS and MTHFR were hypermethylated. Incubation of HRECs with homocysteine increased reactive oxygen species and decreased transcripts of mtDNA-encoded CYTB. Conclusions Compromised transsulfuration and remethylation processes play an important role in the poor removal of retinal homocysteine in diabetic patients. Thus, regulation of their homocysteine levels should ameliorate retinal mitochondrial damage, and by regulating DNA methylation status of the enzymes responsible for homocysteine transsulfuration and remethylation, should prevent excess accumulation of homocysteine.

scholarly journals Retinal Blood Flow in Type 1 Diabetic Patients With No or Mild Diabetic Retinopathy During Euglycemic Clamp

Diabetes Care ◽  
2010 ◽  
Vol 33 (9) ◽  
pp. 2038-2042 ◽  
Author(s):  
B. Pemp ◽  
E. Polska ◽  
G. Garhofer ◽  
M. Bayerle-Eder ◽  
A. Kautzky-Willer ◽  
...  
Keyword(s):  
Blood Flow ◽  
Diabetic Retinopathy ◽  
Retinal Blood Flow ◽  
Diabetic Patients ◽  
Euglycemic Clamp ◽  
Type 1 Diabetic Patients

scholarly journals Prevalence, risk factors and awareness of diabetic retinopathy among admitted diabetic patients at a tertiary level hospital in Kathmandu

2014 ◽  
Vol 6 (1) ◽  
pp. 24-30 ◽  
Author(s):  
Raba Thapa ◽  
Deepak Man Joshi ◽  
Aparna Rizyal ◽  
Nhukesh Maharjan ◽  
Rajesh Dhoj Joshi
Keyword(s):  
Risk Factors ◽  
Diabetic Retinopathy ◽  
Case Series ◽  
Systemic Hypertension ◽  
P Value ◽  
Diabetic Patients ◽  
Duration Of Diabetes ◽  
Case Series Study ◽  
Systemic Problems ◽  
Clinically Significant

Introduction: Diabetic retinopathy (DR) is one of the commonest causes of visual impairment and blindness in Nepal. Objectives: The study aims to explore the prevalence, risk factors and awareness of DR among admitted diabetic patients. Materials and methods: A non-interventional case series study was conducted among the inpatient diabetic cases referred for ophthalmic consultation. The patients’ detailed demographics, awareness on DR, concurrent systemic problems, and glycemic control status were recorded. DR was graded using the Early Treatment Diabetic Retinopathy Study Criteria. Main outcome measures: The prevalence, risk factors and awareness of diabetic retinopathy among the study participants was analyzed. Results: A total of 277 diabetic patients were enrolled in the study. The mean age was 62.25 ± 13.26 years. Only one-third (34.6 %) of the cases were admitted for sugar control and newly diagnosed cases comprised of 19.49 %. Nearly half of the cases (46.6 %) were not aware of diabetic retinopathy and dilated fundus evaluation was done for the first time in 44.4 %. DR was found in 38.26 % of the cases and was diagnosed in 13 % of the new cases. Almost four-fifths (78 %) of the diabetics had had the disease for a duration of 16 to 20 years. Clinically significant macular edema was found in 5.78 % and proliferative DR in 2.52 %. DR was significantly associated with the duration of diabetes (P value = 0.001) and concurrent hypertension (P value = 0.004). Conclusion: The prevalence of DR was 38 % among the admitted diabetic cases and the DR was significantly associated with the duration of diabetes and systemic hypertension. Almost half of the cases had been unaware of DR before referral. This emphasizes the importance of the collaboration of the physician and the ophthalmologist for an early DR detection.   DOI: http://dx.doi.org/10.3126/nepjoph.v6i1.10760   Nepal J Ophthalmol 2014; 6 (2): 24-30

scholarly journals Pericyte Bridges in Homeostasis and Hyperglycemia

2020 ◽  
Author(s):  
Ada Admin ◽  
Bruce A. Corliss ◽  
H. Clifton Ray ◽  
Richard W. Doty ◽  
Corbin Mathews ◽  
...  
Keyword(s):  
Diabetic Retinopathy ◽  
Vascular Remodeling ◽  
Diabetic Control ◽  
Eye Disease ◽  
Diabetic Patients ◽  
Subsequent Increase ◽  
Process Formation ◽  
Retinal Microvasculature ◽  
Pericyte Loss

Diabetic retinopathy is a potentially blinding eye disease that threatens the vision of a ninth of diabetic patients. Progression of the disease has long been attributed to an initial dropout of pericytes that enwrap the retinal microvasculature. Revealed through retinal vascular digests, a subsequent increase in basement membrane bridges is observed. Using cell-specific markers, we demonstrate that pericytes rather than endothelial cells colocalize with these bridges. We show that the density of bridges transiently increases with elevation of Ang-2, PDGF-BB, and blood sugar, is rapidly reversed on a time scale of days, and often associated with a pericyte cell body located off-vessel. Cell-specific knockout of KLF4 in pericytes fully replicates this phenotype. <i>In vivo</i> imaging of limbal vessels demonstrates pericyte migration off-vessel, with rapid pericyte filopodial-like process formation between adjacent vessels. Accounting for off-vessel and on-vessel pericytes, we observe no pericyte loss relative to non-diabetic control retina. These findings reveal the possibility that pericyte perturbations in location and process formation may play a role in the development of pathological vascular remodeling in diabetic retinopathy.

scholarly journals Pericyte Bridges in Homeostasis and Hyperglycemia

2020 ◽  
Author(s):  
Ada Admin ◽  
Bruce A. Corliss ◽  
H. Clifton Ray ◽  
Richard W. Doty ◽  
Corbin Mathews ◽  
...  
Keyword(s):  
Diabetic Retinopathy ◽  
Vascular Remodeling ◽  
Diabetic Control ◽  
Eye Disease ◽  
Diabetic Patients ◽  
Subsequent Increase ◽  
Process Formation ◽  
Retinal Microvasculature ◽  
Pericyte Loss

Diabetic retinopathy is a potentially blinding eye disease that threatens the vision of a ninth of diabetic patients. Progression of the disease has long been attributed to an initial dropout of pericytes that enwrap the retinal microvasculature. Revealed through retinal vascular digests, a subsequent increase in basement membrane bridges is observed. Using cell-specific markers, we demonstrate that pericytes rather than endothelial cells colocalize with these bridges. We show that the density of bridges transiently increases with elevation of Ang-2, PDGF-BB, and blood sugar, is rapidly reversed on a time scale of days, and often associated with a pericyte cell body located off-vessel. Cell-specific knockout of KLF4 in pericytes fully replicates this phenotype. <i>In vivo</i> imaging of limbal vessels demonstrates pericyte migration off-vessel, with rapid pericyte filopodial-like process formation between adjacent vessels. Accounting for off-vessel and on-vessel pericytes, we observe no pericyte loss relative to non-diabetic control retina. These findings reveal the possibility that pericyte perturbations in location and process formation may play a role in the development of pathological vascular remodeling in diabetic retinopathy.

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