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Diabetic retinopathy and ultrawide field imaging.
Ashraf, M, Shokrollahi, S, Salongcay, RP, Aiello, LP, Silva, PS
Seminars in ophthalmology. 2020;(1):56-65
Abstract
The introduction of ultrawide field imaging has allowed the visualization of approximately 82% of the total retinal area compared to only 30% using 7-standard field Early Treatment Diabetic Retinopathy (ETDRS) photography. This substantially wider field of view, while useful in many retinal vascular diseases, is particularly important in diabetic retinopathy where eyes with predominantly peripheral lesions or PPL have been shown to have significantly greater progression rates compared to eyes without PPL. In telemedicine settings, ultrawide field imaging has substantially reduced image ungradable rates and increased rate of disease identification allowing care to be delivered more effectively. Furthermore, the use of ultrawide field fluorescein angiography allows the visualization of significantly more diabetic retinal lesions and allows more accurate quantification of total retinal nonperfusion, with potential implications in the management of diabetic retinopathy and diabetic macular edema. The focus of this paper is to review the current role of ultrawide field imaging in diabetic retinopathy and its possible future role in innovations for retinal image analysis such as artificial intelligence and vessel caliber measurements.
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Imaging and Biomarkers in Diabetic Macular Edema and Diabetic Retinopathy.
Kwan, CC, Fawzi, AA
Current diabetes reports. 2019;(10):95
Abstract
PURPOSE OF REVIEW Diabetic retinopathy (DR) is the leading cause of acquired vision loss in adults across the globe. Early identification and treatment of patients with DR is paramount for vision preservation. The aim of this review paper is to outline current and new imaging techniques and biomarkers that are valuable for clinical diagnosis and management of DR. RECENT FINDINGS Ultrawide field imaging and automated deep learning algorithms are recent advancements on traditional fundus photography and fluorescein angiography. Optical coherence tomography (OCT) and OCT angiography are techniques that image retinal anatomy and vasculature and OCT is routinely used to monitor response to treatment. Many circulating, vitreous, and genetic biomarkers have been studied to facilitate disease detection and development of new treatments. Recent advancements in retinal imaging and identification of promising new biomarkers for DR have the potential to increase detection, risk stratification, and treatment for patients with DR.
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The Diabetic Retinopathy Clinical Research Network (DRCR.net) and Its Contributions to the Treatment of Diabetic Retinopathy.
Sun, JK, Jampol, LM
Ophthalmic research. 2019;(4):225-230
Abstract
Over the past two decades, the Diabetic Retinopathy Clinical Research Network (now known as the DRCR Retina Network) has contributed to multiple and substantial advances in the clinical care of diabetic eye disease. Network studies helped establish anti-vascular endothelial growth factor (VEGF) agents as an effective alternative to panretinal photocoagulation for eyes with proliferative diabetic retinopathy (PDR) and as first-line therapy for eyes with visual impairment for diabetic macular edema (DME), defined treatment algorithms for the use of intravitreal medications in these conditions, and provided critical data to understand how to better evaluate the diabetic eye using optical coherence tomography and other imaging modalities. Ongoing DRCR.net studies will address whether anti-VEGF therapy is effective at preventing vision-threatening complications in eyes with severe non-proliferative diabetic retinopathy, if photobiomodulation has a beneficial effect in eyes with DME, and whether initiation of DME treatment with bevacizumab and rescue with aflibercept can provide visual outcomes as good as those achieved with aflibercept alone. Future plans for the Network also include the expansion into non-diabetic eye disease in areas such as age-related macular degeneration.
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Isolation of Retinal Exosome Biomarkers from Blood by Targeted Immunocapture.
Klingeborn, M, Skiba, NP, Stamer, WD, Bowes Rickman, C
Advances in experimental medicine and biology. 2019;:21-25
Abstract
The retinal pigmented epithelium (RPE) forms the outer blood-retinal barrier, provides nutrients, recycles visual pigment, and removes spent discs from the photoreceptors, among many other functions. Because of these critical roles in visual homeostasis, the RPE is a principal location of disease-associated changes in age-related macular degeneration (AMD), emphasizing its importance for study in both visual health and disease. Unfortunately, there are no early indicators of AMD or disease progression, a void that could be filled by the development of early AMD biomarkers. Exosomes are lipid bilayer membrane vesicles of nanoscale sizes that are released in a controlled fashion by cells and carry out a number of extra- and intercellular activities. In the RPE they are released from both the apical and basal sides, and each source has a unique signature/content. Exosomes released from the basolateral side of RPE cells enter the systemic circulation via the choroid and thus represent a potential source of retinal disease biomarkers in blood. Here we discuss the potential of targeted immunocapture of eye-derived exosomes and other small extracellular vesicles from blood for eye disease biomarker discovery.
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5.
Mechanisms enhancing the protective functions of macular xanthophylls in the retina during oxidative stress.
Widomska, J, Subczynski, WK
Experimental eye research. 2019;:238-246
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Abstract
Macular xanthophylls (MXs) are distinguished from other dietary carotenoids by their high membrane solubility and preferential transmembrane orientation. Additionally, these properties enhance the chemical and physical stability of MXs in the eye retina, and maximize their protective activities. The effectiveness of MXs' protection is also enhanced by their selective accumulation in the most vulnerable domains of retinal membranes. The retina is protected by MXs mainly through blue-light filtration, quenching of the excited triplet states of potent photosensitizers, and physical quenching of singlet oxygen. To perform these physical, photo-related actions, the structure of MXs should remain intact. However, the conjugated double-bond structure of MXs makes them highly chemically reactive and susceptible to oxidation. Chemical quenching of singlet oxygen and scavenging of free radicals destroy their intact structure and consume MXs. Consequently, their physical actions, which are critical to the protection of retina, are diminished. Thus, it is timely and important to identify mechanisms whereby the chemical destruction (bleaching) of MXs in retinal membranes can be reduced. It was shown that nitroxide free radicals (spin labels) located in membranes protect MXs against destruction, and their effect is especially pronounced during the light-induced formation of singlet oxygen. That should extend and enhance their positive action in the retina through physical processes. In this review, we will discuss possible applications of this new strategy during ophthalmological procedures, which can cause acute bleaching of MXs and damage the retina through oxidative processes.
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Update on Screening for Sight-Threatening Diabetic Retinopathy.
Scanlon, PH
Ophthalmic research. 2019;(4):218-224
Abstract
PURPOSE The aim of this article was to describe recent advances in the use of new technology in diabetic retinopathy screening by looking at studies that assessed the effectiveness and cost-effectiveness of these technologies. METHODS The author conducts an ongoing search for articles relating to screening or management of diabetic retinopathy utilising Zetoc with keywords and contents page lists from relevant journals. RESULTS The areas discussed in this article are reference standards, alternatives to digital photography, area of retina covered by the screening method, size of the device and hand-held cameras, mydriasis versus non-mydriasis or a combination, measurement of distance visual acuity, grading of images, use of automated grading analysis and cost-effectiveness of the new technologies. CONCLUSIONS There have been many recent advances in technology that may be adopted in the future by screening programmes for sight-threatening diabetic retinopathy but each device will need to demonstrate effectiveness and cost-effectiveness before more widespread adoption.
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Diabetic retinopathy techniques in retinal images: A review.
Salamat, N, Missen, MMS, Rashid, A
Artificial intelligence in medicine. 2019;:168-188
Abstract
The diabetic retinopathy is the main reason of vision loss in people. Medical experts recognize some clinical, geometrical and haemodynamic features of diabetic retinopathy. These features include the blood vessel area, exudates, microaneurysm, hemorrhages and neovascularization, etc. In Computer Aided Diagnosis (CAD) systems, these features are detected in fundus images using computer vision techniques. In this paper, we review the methods of low, middle and high level vision for automatic detection and classification of diabetic retinopathy.We give a detailed review of 79 algorithms for detecting different features of diabetic retinopathy during the last eight years.
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A Review of Pathogenic Drivers of Age-Related Macular Degeneration, Beyond Complement, with a Focus on Potential Endpoints for Testing Therapeutic Interventions in Preclinical Studies.
Choudhary, M, Malek, G
Advances in experimental medicine and biology. 2019;:9-13
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Abstract
Age-related macular degeneration (AMD) continues to be the leading cause of visual impairment for the elderly in developed countries. It is a complex, multifactorial, progressive disease with diverse molecular pathways regulating its pathogenesis. One of the cardinal features of the early clinical subtype of AMD is the accumulation of lipid- and protein-rich deposits within Bruch's membrane, called drusen, which can be visualized by fundus imaging. Currently, multiple in vitro and in vivo model systems exist, which can be used to help tease out mechanisms associated with different molecular pathways driving disease initiation and progression. Given the lack of treatments for patients suffering from the dry form of AMD, it is imperative to appreciate the different known morphological endpoints associated with the various pathogenic pathways, in order to derive further insights, for the ultimate purpose of disease modeling and development of effective therapeutic interventions.
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Sickle cell retinopathy. A focused review.
Abdalla Elsayed, MEA, Mura, M, Al Dhibi, H, Schellini, S, Malik, R, Kozak, I, Schatz, P
Graefe's archive for clinical and experimental ophthalmology = Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie. 2019;(7):1353-1364
Abstract
PURPOSE To provide a focused review of sickle cell retinopathy in the light of recent advances in the pathogenesis, multimodal retinal imaging, management of the condition, and migration trends, which may lead to increased prevalence of the condition in the Western world. METHODS Non-systematic focused literature review. RESULTS Sickle retinopathy results from aggregation of abnormal hemoglobin in the red blood cells in the retinal microcirculation, leading to reduced deformability of the red blood cells, stagnant blood flow in the retinal precapillary arterioles, thrombosis, and ischemia. This may be precipitated by hypoxia, acidosis, and hyperosmolarity. Sickle retinopathy may result in sight threatening complications, such as paracentral middle maculopathy or sequelae of proliferative retinopathy, such as vitreous hemorrhage and retinal detachment. New imaging modalities, such as wide-field imaging and optical coherence tomography angiography, have revealed the microstructural features of sickle retinopathy, enabling earlier diagnosis. The vascular growth factor ANGPTL-4 has recently been identified as a potential mediator of progression to proliferative retinopathy and may represent a possible therapeutic target. Laser therapy should be considered for proliferative retinopathy in order to prevent visual loss; however, the evidence is not very strong. With recent development of wide-field imaging, targeted laser to ischemic retina may prove to be beneficial. Exact control of intraoperative intraocular pressure, including valved trocar vitrectomy systems, may improve the outcomes of vitreoretinal surgery for complications, such as vitreous hemorrhage and retinal detachment. Stem cell transplantation and gene therapy are potentially curative treatments, which may prevent retinopathy. CONCLUSIONS There is lack of evidence regarding the optimal management of sickle retinopathy. Further study is needed to determine if recent progress in the understanding of the pathophysiology and diagnosis of sickle retinopathy may translate into improved management and outcome.
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Imaging Biomarkers in Diabetic Retinopathy and Diabetic Macular Edema.
Mehta, N, Tsui, E, Lee, GD, Dedania, V, Modi, Y
International ophthalmology clinics. 2019;(1):241-262