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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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Vitreous and intraretinal macular changes in diabetic macular edema with and without tractional components.
Romano, MR, Allegrini, D, Della Guardia, C, Schiemer, S, Baronissi, I, Ferrara, M, Cennamo, G
Graefe's archive for clinical and experimental ophthalmology = Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie. 2019;(1):1-8
Abstract
Diabetic macular edema (DME) is still one of the main causes of visual impairment. Repeated intravitreal injections of ranibizumab are considered the gold standard treatment, but the efficacy in patients with prominent cystic characteristics remains uncertain. In diabetic retinas, the identification of both antero-posterior and, particularly, tangential tractions is crucial to prevent misdiagnosis of tractional and refractory DME, and therefore to prevent poor treatment outcomes. The treatment of tractional DME with anti-VEGF injections could be poorly effective due to the influence of a tractional force. Pars plana vitrectomy (PPV) is a surgical procedure that has been widely used in the treatment of diffuse and refractory DME. Anatomical improvement, although stable and immediate, did not result in visual improvement. PPV with internal limiting membrane (ILM) peeling for the treatment of non-tractional DME in patients with prominent cysts (> 390 μm) causes subfoveal atrophy, defined as "floor effect". Epiretinal tangential forces and intraretinal change evaluation by SD-OCT of non-tractional DME are essential for determining appropriate management.
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Differentiation of Underlying Pathologies of Macular Edema Using Spectral Domain Optical Coherence Tomography (SD-OCT).
Dysli, M, Rückert, R, Munk, MR
Ocular immunology and inflammation. 2019;(3):474-483
Abstract
Purpose: To describe the morphological characteristics of macular edema (ME) of different origins using spectral domain optical coherence tomography (SD-OCT). Methods: This article summarizes and highlights key morphologic findings, based on published articles, describing the characteristic presentations of ME of different origins using SD-OCT. The following pathologies were included: uveitic macular edema, pseudophakic cystoid macular edema (PCME), diabetic macular edema (DME), macular edema secondary to central or branch retinal vein occlusion (CRVO/BRVO), microcystic macular edema (MME), ME associated with epiretinal membrane (ERM), and retinitis pigmentosa (RP). Conclusions: Macular edema of different origins show characteristic patterns that are often indicative of the underlying cause and pathology. Thus, trained algorithms may in the future be able to automatically differentiate underlying causes and support clinical diagnosis. Knowledge of different appearances support the clinical diagnosis and can lead to improved and more targeted treatment of ME.
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Asian age-related macular degeneration: from basic science research perspective.
Yanagi, Y, Foo, VHX, Yoshida, A
Eye (London, England). 2019;(1):34-49
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Abstract
In Asian populations, polypoidal choroidal vasculopathy (PCV), a distinct phenotype of neovascular age-related macular degeneration (AMD), is more prevalent than Caucasians. Recently, there has been significant focus on how PCV differs from typical AMD. Although typical AMD and PCV share a variety of mechanisms by which abnormal angiogenic process occurs at the retinochoroidal interface, PCV has different clinical characteristics such as aneurysm-like dilation at the terminal of choroidal neovascular membranes, less frequent drusen and inner choroidal degeneration due to the thickened choroid. Recent studies support an important role for inflammation, angiogenesis molecules and lipid metabolism in the pathogenesis of neovascular AMD. Furthermore, although less attention has been paid to the role of the choroid in AMD, accumulating evidence suggests that the choriocapillaris and choroid also play a pivotal role in drusenogenesis, typical AMD and PCV. This review discusses the basic pathogenic mechanisms of AMD and explores the difference between typical AMD and PCV.
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Retinal Manifestations of Juvenile Dermatomyositis: Case Report of Bilateral Diffuse Chorioretinopathy with Paracentral Acute Middle Maculopathy and Review of the Literature.
Choi, RY, Swan, RJ, Hersh, A, Vitale, AT
Ocular immunology and inflammation. 2018;(6):929-933
Abstract
PURPOSE To review a case of bilateral diffuse chorioretinopathy as a presenting sign of juvenile dermatomyositis (JDM) and review the literature regarding retinal manifestations associated with this disease. METHODS Review of case record and literature regarding retinal manifestations related to juvenile dermatomyositis. RESULTS A 13-year-old girl presented with bilateral diffuse chorioretinopathy as the presenting sign of juvenile dermatomyositis. A review of the literature suggests that retinopathy associated with JDM is a rare finding that is symptomatic to patients and often responds to systemic treatment of juvenile dermatomyositis. This is also the first documented case of paracentral acute middle maculopathy in the setting of juvenile dermatomyositis. CONCLUSION Chorioretinopathy is a rare finding in juvenile dermatomyositis. While all patients with JDM likely do not warrant screening ophthalmologic examinations, any patient who has visual symptoms should have a careful dilated examination to evaluate for retinopathy or steroid-induced cataracts.
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Antecedents of Soft Drusen, the Specific Deposits of Age-Related Macular Degeneration, in the Biology of Human Macula.
Curcio, CA
Investigative ophthalmology & visual science. 2018;(4):AMD182-AMD194
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Abstract
AMD pathobiology was irreversibly changed by the recent discovery of extracellular cholesterol-containing deposits in the subretinal space, between the photoreceptors and retinal pigment epithelium (RPE), called subretinal drusenoid deposits (SDDs). SDDs strikingly mirror the topography of rod photoreceptors in human macula, raising the question of whether an equivalent process results in a deposition related to foveal cones. Herein we propose that AMD's pathognomonic lesion-soft drusen and basal linear deposit (BLinD, same material, diffusely distributed)-is the leading candidate. Epidemiologic, clinical, and histologic data suggest that these deposits are most abundant in the central macula, under the fovea. Strong evidence presented in a companion article supports the idea that the dominant ultrastructural component is large apolipoprotein B,E-containing lipoproteins, constitutively secreted by RPE. Lipoprotein fatty acids are dominated by linoleate (implicating diet) rather than docosahexaenoate (implicating photoreceptors); we seek within the retina cellular relationships and dietary drivers to explain soft druse topography. The delivery of xanthophyll pigments to highly evolved and numerous Müller cells in the human fovea, through RPE, is one strong candidate, because Müller cells are the main reservoir of these pigments, which replenish from diet. We propose that the evolution of neuroglial relations and xanthophyll delivery that underlie exquisite human foveal vision came with a price, that is, soft drusen and sequela, long after our reproductive years.
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Retinal complications of gout: a case report and review of the literature.
Jiang, Y, Brenner, JE, Foster, WJ
BMC ophthalmology. 2018;(1):11
Abstract
BACKGROUND There have been few reported findings of posterior segment complications of gout. While exudative lesions, an increased risk of macular degeneration, and vascular occlusions have been previously reported, to our knowledge, refractile macular lesions have not been reported in a patient with chronic uncontrolled gout. CASE PRESENTATION Highly refractile, crystal-like lesions were found in the macula of a 62 year old male patient with chronically uncontrolled gout. The lesions appeared at the termination of retinal arterioles and were located at the level of the retinal pigment epithelium. The lesions did not stain with fluorescein and were associated with larger areas geographic atrophy. Review of the patient's blood tests revealed well-controlled vasculopathic risk factors. Fundus appearance and best-corrected visual acuity remained stable over 12 months of follow-up during which the uric acid levels were well controlled. CONCLUSION Retinopathy may be associated with chronically uncontrolled gout and patients with visual complaints should undergo a dilated examination in addition to the typical anterior segment slit-lamp exam.
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Management of Diabetic Macular Edema.
Moisseiev, E, Loewenstein, A
Ophthalmic research. 2017;(1):15-17
Abstract
Diabetic macular edema is a common condition frequently encountered by ophthalmologists. In this piece we briefly review its definition, pathogenesis, clinical aspects, imaging, and treatment.
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Optical Coherence Tomography Angiography in Diabetic Maculopathy.
Coscas, G, Lupidi, M, Coscas, F
Developments in ophthalmology. 2017;:38-49
Abstract
Fluorescein angiography (FA) and indocyanine green angiography have provided information about the normal retinal and choroidal anatomy, nearly comparable to histological findings. These tests have been fundamental in the evaluation of all retinal and choroidal vascular diseases and have allowed clinicians to define and diagnose several pathological conditions. FA became the "gold standard" in retinal imaging due to the capacity to visualize the retinal capillary bed and its changes, both in the macular area and in the periphery. Although the fluorescence of the injected dye enabled improved visualization of retinal capillaries, not all the different layers of the retinal capillary network could be visualized in this bi-dimensional examination, mainly because of the light scattering phenomenon. By calculating the difference between static and non-static tissues, optical coherence tomography angiography (OCT-A) allows a depth-resolved visualization of the retinal and choroidal microvasculature. Given that the main moving elements in the ocular fundus are contained in blood vessels, determining a vascular decorrelation signal enables visualization of the 3-dimensional retinal and choroidal vascular networks without the intravenous dye injection, reducing therefore the risk of potential adverse events. Since OCT-A is perfectly co-registered with its structural OCT, both morphological findings, such as macular edema, and functional ones, like capillary drop-out, may be clearly evaluated on a single dye-free examination. Proficient detection of the different findings in diabetic maculopathy on OCT-A can result in a rapid analysis of the examination, and in the capacity to distinguish truly decorrelated structures (perfused vessels) from artifacts. Moreover, a complete morpho-functional assessment may help in determining both the origin and the clinical activity of a given vascular disease.
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Vitreous anatomy and the vitreomacular correlation.
Kishi, S
Japanese journal of ophthalmology. 2016;(4):239-73
Abstract
The presence of a posterior precortical vitreous pocket, referred to as a precortical pocket, implies that the vitreous cortex is formed into a collagen sheet separated from the gel in the macula. Along with strong vitreoretinal attachment at the fovea, the precortical pocket plays a role in perifoveal posterior vitreous detachments, which may lead to macular holes, premacular membranes, and ring-shaped proliferation in diabetic retinopathy. I and my colleagues published pioneer studies of the vitreous in postmortem eyes. Here, the role of the precortical pocket in various vitreoretinal interface diseases is discussed. Swept-source optical coherence tomography showed development of the precortical pocket, the connecting channel, and Cloquet's canal during early childhood. These findings raised the possibility that aqueous humor may drain into the precortical pocket. The physiologic role of the drainage route is also discussed. Crosstalk between the anterior chamber and macula is an attractive hypothesis and remains to be elucidated.