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Journal of Ophthalmic & Vision Research 2018Optical coherence angiography (OCTA) is a noninvasive technique that has been introduced in recent years to detect ophthalmological pathology. The growing usage of OCTA... (Review)
Review
Optical coherence angiography (OCTA) is a noninvasive technique that has been introduced in recent years to detect ophthalmological pathology. The growing usage of OCTA to detect retinal abnormalities can be attributed to its advantages over the reference-standard fluorescein angiography (FA), although both of these techniques can be used in association. OCTA's advantages include its dye independency, its ability to produce depth-resolved images of retinal and choroidal vessels that yield images of different vascular layers of the retina, and the better delineation of the foveal avascular zone. OCTA's disadvantages include the lack of normalized patient data, artefactual projection issues, and its inability to detect low-flow lesions or pathologic conditions. Different OCTA platforms use unique algorithms to detect microvasculature, which are implemented in both spectral-domain (SD) and swept-source (SS) OCT machines. Microvascular changes in retinal vein occlusions (RVOs) are visible in both the superficial and deep capillary networks of the retina in OCTA. These visualizations include a decrease in foveal and parafoveal vascular densities, non-perfusion areas, capillary engorgement and telangiectasias, vascular tortuosity, microaneurysms, disruption of the foveal perivascular plexus, and formation of collateral vessels. The restricted field of view and inability to show leakage are important limitations associated with the use of OCTA in RVO cases. In this article, we present a brief overview of OCTA and a review of the changes detectable in different slabs by OCTA in RVO cases published in PubMed and Embase.
PubMed: 30090189
DOI: 10.4103/jovr.jovr_264_17 -
Romanian Journal of Ophthalmology 2023Diabetic retinopathy (DR) is a vision-threatening complication of diabetes, necessitating early and accurate diagnosis. The combination of optical coherence tomography... (Review)
Review
Diabetic retinopathy (DR) is a vision-threatening complication of diabetes, necessitating early and accurate diagnosis. The combination of optical coherence tomography (OCT) imaging with convolutional neural networks (CNNs) has emerged as a promising approach for enhancing DR diagnosis. OCT provides detailed retinal morphology information, while CNNs analyze OCT images for automated detection and classification of DR. This paper reviews the current research on OCT imaging and CNNs for DR diagnosis, discussing their technical aspects and suitability. It explores CNN applications in detecting lesions, segmenting microaneurysms, and assessing disease severity, showing high sensitivity and accuracy. CNN models outperform traditional methods and rival expert ophthalmologists' results. However, challenges such as dataset availability and model interpretability remain. Future directions include multimodal imaging integration and real-time, point-of-care CNN systems for DR screening. The integration of OCT imaging with CNNs has transformative potential in DR diagnosis, facilitating early intervention, personalized treatments, and improved patient outcomes. DR = Diabetic Retinopathy, OCT = Optical Coherence Tomography, CNN = Convolutional Neural Network, CMV = Cytomegalovirus, PDR = Proliferative Diabetic Retinopathy, AMD = Age-Related Macular Degeneration, VEGF = vascular endothelial growth factor, RAP = Retinal Angiomatous Proliferation, OCTA = OCT Angiography, AI = Artificial Intelligence.
Topics: Humans; Diabetic Retinopathy; Tomography, Optical Coherence; Macular Edema; Vascular Endothelial Growth Factor A; Artificial Intelligence; Neural Networks, Computer; Macular Degeneration; Diabetes Mellitus
PubMed: 38239418
DOI: 10.22336/rjo.2023.63 -
Translational Vision Science &... Feb 2021To use high-resolution histology to define the associations between microaneurysms, capillary diameter and capillary density alterations in diabetic retinopathy (DR).
PURPOSE
To use high-resolution histology to define the associations between microaneurysms, capillary diameter and capillary density alterations in diabetic retinopathy (DR).
METHODS
Quantitative comparisons of microaneurysm number, capillary density and capillary diameter were performed between eight human donor eyes with nonproliferative DR and six age- and eccentricity-matched normal donor eyes after retinal vascular perfusion labelling. The parafovea, 3-mm, 6-mm, and 9-mm retinal eccentricities were analyzed and associations between microvascular alterations defined.
RESULTS
Mean capillary density was reduced in all retina regions in the DR group (P = 0.013). Microaneurysms occurred in all retina regions in the DR group, but the association between decreased capillary density and microaneurysm number was only significant in the 3-mm (P = 0.040) and 6-mm (P = 0.007) eccentricities. The mean capillary diameter of the DR group (8.9 ± 0.53 µm) was greater than the control group (7.60 ± 0.40 µm; P = 0.033). There was no association between capillary diameter increase and capillary density decrease (P = 0.257) and capillary diameter increase and microaneurysm number (P = 0.147) in the DR group. Within the parafovea of the DR group, capillary density was significantly reduced, and capillary diameter was significantly increased in the deep capillary plexus compared with the superficial and intermediate plexuses (all P < 0.05).
CONCLUSIONS
In DR, capillary density reduction occurs across multiple retina eccentricities with a predilection for the deep capillary plexus. The association between microaneurysm number and capillary density is specific to retina eccentricity. Capillary diameter increase may be an early biomarker of DR. These findings may refine the application of optical coherence tomography angiography techniques for the management of DR.
Topics: Diabetes Mellitus; Diabetic Retinopathy; Fluorescein Angiography; Humans; Microaneurysm; Microscopy, Confocal; Retinal Vessels; Tomography, Optical Coherence
PubMed: 34003893
DOI: 10.1167/tvst.10.2.6 -
Journal of Anatomy Oct 2023The aim of this study is to correlate small dot hyper-reflective foci (HRF) observed in spectral domain optical coherence tomography (SD-OCT) scans of an animal model of...
The aim of this study is to correlate small dot hyper-reflective foci (HRF) observed in spectral domain optical coherence tomography (SD-OCT) scans of an animal model of hyperglycaemia with focal electroretinography (fERG) response and immunolabelling of retinal markers. The eyes of an animal model of hyperglycaemia showing signs of diabetic retinopathy (DR) were imaged using SD-OCT. Areas showing dot HRF were further evaluated using fERG. Retinal areas enclosing the HRF were dissected and serially sectioned, stained and labelled for glial fibrillary acidic protein (GFAP) and a microglial marker (Iba-1). Small dot HRF were frequently seen in OCT scans in all retinal quadrants in the inner nuclear layer or outer nuclear layer in the DR rat model. Retinal function in the HRF and adjacent areas was reduced compared with normal control rats. Microglial activation was detected by Iba-1 labelling and retinal stress identified by GFAP expression in Müller cells observed in discrete areas around small dot HRF. Small dot HRF seen in OCT images of the retina are associated with a local microglial response. This study provides the first evidence of dot HRF correlating with microglial activation, which may allow clinicians to better evaluate the microglia-mediated inflammatory component of progressive diseases showing HRF.
Topics: Rats; Animals; Diabetic Retinopathy; Tomography, Optical Coherence; Retina; Inflammation; Hyperglycemia; Diabetes Mellitus
PubMed: 37222261
DOI: 10.1111/joa.13889 -
Medicina (Kaunas, Lithuania) Jul 2023: This study aimed to elucidate the role of laser photocoagulation therapy in the treatment of diabetic macular edema (DME) as an alternative to, or in conjunction with,... (Review)
Review
: This study aimed to elucidate the role of laser photocoagulation therapy in the treatment of diabetic macular edema (DME) as an alternative to, or in conjunction with, the first-line treatment, anti-vascular endothelial growth factor (VEGF). : A comprehensive literature search to identify studies that evaluated the efficacy of laser photocoagulation therapy in the management of DME was performed. The relevant findings of the efficacy of focal/grid laser therapy from data in randomized, controlled trials were synthesized, and the potential of new laser technologies, such as navigated laser systems, pattern scan lasers, and subthreshold lasers, was explored. The usefulness of multimodal imaging-guided laser therapy was also evaluated, with a focus on the potential contribution to anti-VEGF therapy. : Focal laser photocoagulation targeting microaneurysms remains an effective therapeutic approach to chronic refractory edema, despite the widespread use of anti-VEGF therapy. To achieve the best possible treatment outcomes, precise identification of microaneurysms is essential. This requires the use of multimodal imaging-guided, highly accurate, minimally invasive coagulation techniques. Subthreshold laser therapy can also reduce the frequency of anti-VEGF injections and minimize treatment burden. : Further studies are needed to determine the optimal timing and settings for laser photocoagulation therapy and the potential of new laser technologies in the management of DME. Nevertheless, laser photocoagulation therapy plays an important role in the management of DME, in conjunction with anti-VEGF therapy.
Topics: Humans; Macular Edema; Diabetic Retinopathy; Microaneurysm; Laser Coagulation; Laser Therapy; Treatment Outcome; Diabetes Mellitus
PubMed: 37512130
DOI: 10.3390/medicina59071319 -
Cirugia Espanola Oct 2005The aim of this study was to review our experience in the diagnosis and treatment of visceral artery aneurysms.
INTRODUCTION
The aim of this study was to review our experience in the diagnosis and treatment of visceral artery aneurysms.
MATERIAL AND METHOD
We performed a retrospective study through review of the medical records of patients diagnosed with visceral aneurysms from 1984 to 2003. Diagnosis, treatment and follow-up were analyzed.
RESULTS
Thirty-two aneurysms were diagnosed in 27 patients (17 men and 10 women). There were 12 aneurysms of the splanchnic artery, six of the hepatic artery, five of the celiac trunk, three gastroduodenal, one jejunal, one pancreaticoduodenal, one superior mesenteric--associated with a splanchnic, renal and celiac trunk aneurysm--, one inferior mesenteric, one cystic artery and one case of parenchymatous hepatorenal microaneurysms. Eight aneurysms were not treated. Three underwent embolization. One aneurysm was excluded with a covered endoprosthesis. Twenty aneurysms were treated surgically. Ligature or exclusion was performed in 11 patients, hepatic lobectomy in one patient, resection with revascularization in four patients, endoaneurysmorrhaphy in three patients and simple suture was performed in one hepatic artery pseudoaneurysm.
CONCLUSIONS
Current diagnostic techniques favor early and sometimes minimally invasive treatment. Splanchnic aneurysms are more difficult to diagnose and require highly varied repair techniques.
Topics: Adult; Aged; Aged, 80 and over; Aneurysm; Celiac Artery; Female; Follow-Up Studies; Humans; Male; Mesenteric Arteries; Middle Aged; Retrospective Studies; Viscera
PubMed: 16420833
DOI: 10.1016/s0009-739x(05)70926-x -
British Journal of Pharmacology Jan 2012Diabetic retinopathy (DR) is one of the most common microvascular complications of diabetes and remains a major cause of preventable blindness among adults at working... (Review)
Review
Diabetic retinopathy (DR) is one of the most common microvascular complications of diabetes and remains a major cause of preventable blindness among adults at working age. DR involves an abnormal pathology of major retinal cells, including retinal pigment epithelium, microaneurysms, inter-retinal oedema, haemorrhage, exudates (hard exudates) and intraocular neovascularization. The biochemical mechanisms associated with hyperglycaemic-induced DR are through multifactorial processes. Peroxisome proliferator-activated receptor-γ (PPAR-γ) plays an important role in the pathogenesis of DR by inhibiting diabetes-induced retinal leukostasis and leakage. Despite DR causing eventual blindness, only a few visual or ophthalmic symptoms are observed until visual loss develops. Therefore, early medical interventions and prevention are the current management strategies. Laser photocoagulation therapy is the most common treatment. However, this therapy may cause retinal damage and scarring. Herbal and traditional natural medicines may provide an alternative to prevent or delay the progression of DR. This review provides an analysis of the therapeutic potential of herbal and traditional natural medicines or their active components for the slowdown of progression of DR and their possible mechanism through the PPAR-γ pathway.
Topics: Biological Products; Diabetic Retinopathy; Humans; PPAR gamma; Plants, Medicinal; Retina
PubMed: 21480863
DOI: 10.1111/j.1476-5381.2011.01411.x -
Computational and Structural... 2016In this paper, we give a review on automatic image processing tools to recognize diseases causing specific distortions in the human retina. After a brief summary of the... (Review)
Review
In this paper, we give a review on automatic image processing tools to recognize diseases causing specific distortions in the human retina. After a brief summary of the biology of the retina, we give an overview of the types of lesions that may appear as biomarkers of both eye and non-eye diseases. We present several state-of-the-art procedures to extract the anatomic components and lesions in color fundus photographs and decision support methods to help clinical diagnosis. We list publicly available databases and appropriate measurement techniques to compare quantitatively the performance of these approaches. Furthermore, we discuss on how the performance of image processing-based systems can be improved by fusing the output of individual detector algorithms. Retinal image analysis using mobile phones is also addressed as an expected future trend in this field.
PubMed: 27800125
DOI: 10.1016/j.csbj.2016.10.001 -
Current Medicinal Chemistry 2013The onset of diabetic retinopathy is characterized by morphologic alterations of the microvessels, with thickening of the basement membrane, loss of inter-endothelial... (Review)
Review
The onset of diabetic retinopathy is characterized by morphologic alterations of the microvessels, with thickening of the basement membrane, loss of inter-endothelial tight junctions and early and selective loss of pericytes, together with increased vascular permeability, capillary occlusions, microaneurysms and, later, loss of endothelial cells (EC). A key role in the evolution of the disease is played by pericytes, specialized contractile mesenchymal cells of mesodermal origin, that, in capillaries, exert a function similar to smooth muscle cells in larger vessels, regulating vascular tone and perfusion pressure. Thickening of the basement membrane, together with systemic and local hypertension, hyperglycaemia, advanced glycation end-product formation and hypoxia, may disrupt the tight link between pericytes and EC causing pericyte apoptosis, while endothelium, deprived of proliferation control, can give rise to new vessels. Pericyte dropout has great consequences on capillary remodelling and may cause the first abnormalities of the diabetic eye which can be observed clinically. Hyperglycaemia and local hypertension are known to be a direct cause of pericyte apoptosis and dropout, and intracellular biochemical pathways of the glucose metabolites have been explored. However, the exact mechanisms are not yet fully understood and need further clarification in order to develop new effective drugs for the prevention of retinopathy.
Topics: Animals; Apoptosis; Diabetic Retinopathy; Endothelial Cells; Humans; Microvessels; Pericytes
PubMed: 23745544
DOI: 10.2174/09298673113209990022 -
Nature Reviews. Nephrology Jan 2011The mechanisms that drive the development of diabetic nephropathy remain undetermined. Only 30-40% of patients with diabetes mellitus develop overt nephropathy, which... (Review)
Review
The mechanisms that drive the development of diabetic nephropathy remain undetermined. Only 30-40% of patients with diabetes mellitus develop overt nephropathy, which suggests that other contributing factors besides the diabetic state are required for the progression of diabetic nephropathy. Endothelial dysfunction is associated with human diabetic nephropathy and retinopathy, and advanced diabetic glomerulopathy often exhibits thrombotic microangiopathy, including glomerular capillary microaneurysms and mesangiolysis, which are typical manifestations of endothelial dysfunction in the glomerulus. Likewise, diabetic mice with severe endothelial dysfunction owing to deficiency of endothelial nitric oxide synthase develop progressive nephropathy and retinopathy similar to the advanced lesions observed in humans with diabetes mellitus. Additionally, inhibitors of the renin-angiotensin system fail to be renoprotective in some individuals with diabetic nephropathy (due in part to aldosterone breakthrough) and in some mouse models of the disease. In this Review, we discuss the clinical and experimental evidence that supports a role for endothelial nitric oxide deficiency and subsequent endothelial dysfunction in the progression of diabetic nephropathy and retinopathy. If endothelial dysfunction is the key factor required for diabetic nephropathy, then agents that improve endothelial function or raise intraglomerular nitric oxide level could be beneficial in the treatment of diabetic nephropathy.
Topics: Animals; Diabetic Angiopathies; Diabetic Nephropathies; Disease Models, Animal; Endothelium, Vascular; Humans; Mice
PubMed: 21045790
DOI: 10.1038/nrneph.2010.152