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Faust CD, Klettner CA, Toso M, Hageman GS, Eames I, Luthert PJ, Zouache MA. The vascular geometry of the choriocapillaris is associated with spatially heterogeneous molecular exchange with the outer retina. J Physiol 2024; 602:1273-1295. [PMID: 38513000 DOI: 10.1113/jp285050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 02/14/2024] [Indexed: 03/23/2024] Open
Abstract
Vision relies on the continuous exchange of material between the photoreceptors, retinal pigment epithelium and choriocapillaris, a dense microvascular bed located underneath the outer retina. The anatomy and physiology of the choriocapillaris and their association with retinal homeostasis have proven difficult to characterize, mainly because of the unusual geometry of this vascular bed. By analysing tissue dissected from 81 human eyes, we show that the thickness of the choriocapillaris does not vary significantly over large portions of the macula or with age. Assessments of spatial variations in the anatomy of the choriocapillaris in three additional human eyes indicate that the location of arteriolar and venular vessels connected to the plane of the choriocapillaris is non-random, and that venular insertions cluster around arteriolar ones. Mathematical models built upon these anatomical analyses reveal that the choriocapillaris contains regions where the transport of passive elements is dominated by diffusion, and that these diffusion-limited regions represent areas of reduced exchange with the outer retina. The width of diffusion-limited regions is determined by arterial flow rate and the relative arrangement of arteriolar and venular insertions. These analyses demonstrate that the apparent complexity of the choriocapillaris conceals a fine balance between several anatomical and functional parameters to effectively support homeostasis of the outer retina. KEY POINTS: The choriocapillaris is the capillary bed supporting the metabolism of photoreceptors and retinal pigment epithelium, two critical components of the visual system located in the outer part of the retina. The choriocapillaris has evolved a planar multipolar vascular geometry that differs markedly from the branched topology of most vasculatures in the human body. Here, we report that this planar multipolar vascular geometry is associated with spatially heterogenous molecular exchange between choriocapillaris and outer retina. Our data and analyses highlight a necessary balance between choriocapillaris anatomical and functional parameters to effectively support homeostasis of the outer retina.
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Affiliation(s)
- Caitlin D Faust
- John A. Moran Eye Center, Department of Ophthalmology & Visual Sciences, University of Utah, Salt Lake City, Utah, USA
| | | | - Marc Toso
- John A. Moran Eye Center, Department of Ophthalmology & Visual Sciences, University of Utah, Salt Lake City, Utah, USA
| | - Gregory S Hageman
- John A. Moran Eye Center, Department of Ophthalmology & Visual Sciences, University of Utah, Salt Lake City, Utah, USA
| | - Ian Eames
- Department of Mechanical Engineering, University College London, London, UK
| | - Philip J Luthert
- Institute of Ophthalmology, University College London, London, UK
| | - Moussa A Zouache
- John A. Moran Eye Center, Department of Ophthalmology & Visual Sciences, University of Utah, Salt Lake City, Utah, USA
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Taylor TRP, Menten MJ, Rueckert D, Sivaprasad S, Lotery AJ. The role of the retinal vasculature in age-related macular degeneration: a spotlight on OCTA. Eye (Lond) 2024; 38:442-449. [PMID: 37673970 PMCID: PMC10858204 DOI: 10.1038/s41433-023-02721-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 06/27/2023] [Accepted: 08/25/2023] [Indexed: 09/08/2023] Open
Abstract
Age-related macular degeneration (AMD) remains a disease with high morbidity and an incompletely understood pathophysiological mechanism. The ocular blood supply has been implicated in the development of the disease process, of which most research has focused on the role of the choroid and choriocapillaris. Recently, interest has developed into the role of the retinal vasculature in AMD, particularly with the advent of optical coherence tomography angiography (OCTA), which enables non-invasive imaging of the eye's blood vessels. This review summarises the up-to-date body of work in this field including the proposed links between observed changes in the retinal vessels and the development of AMD and potential future directions for research in this area. The review highlights that the strongest evidence supports the observation that patients with early to intermediate AMD have reduced vessel density in the superficial vascular complex of the retina, but also emphasises the need for caution when interpreting such studies due to their variable methodologies and nomenclature.
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Affiliation(s)
- Thomas R P Taylor
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK
| | - Martin J Menten
- BioMedIA, Imperial College London, London, UK
- Institute for AI and Informatics in Medicine, Klinikum Rechts der Isar, Technical University Munich, Munich, Germany
| | - Daniel Rueckert
- BioMedIA, Imperial College London, London, UK
- Institute for AI and Informatics in Medicine, Klinikum Rechts der Isar, Technical University Munich, Munich, Germany
| | - Sobha Sivaprasad
- NIHR Moorfields Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Andrew J Lotery
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK.
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Ng K, Xu P, Jin G, Cheng W, Luo X, Ding X, Zheng D, Liu Y. Quantitative analysis of choriocapillaris flow deficits and choroidal thickness in children with Marfan syndrome. Br J Ophthalmol 2024; 108:274-279. [PMID: 36575623 DOI: 10.1136/bjo-2022-322535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 12/02/2022] [Indexed: 12/24/2022]
Abstract
PURPOSE To evaluate the characteristics and associated factors of choroidal thickness (ChT) and choriocapillaris flow deficit percentage (CC FD%) in children with Marfan syndrome (MFS). METHODS This is a cross-sectional study. The ChT of the subfoveal area and other areas 0.5, 1.5, and 2.5 mm away from the fovea were assessed. The CC FD% of quadrant and circular regions with diameters of 0.5, 1.5 and 2.5 mm were assessed with 3×3 mm macular choriocapillaris images. Best-corrected visual acuity (BCVA) and cardiac function factor such as Z score were measured to analyse the associations with ChT and CC FD%. RESULTS 51 MFS children and 50 healthy controls were enrolled in this study. Compared with the healthy controls, the ChT in the MFS group was thinner in the subfoveal area, temporal 0.5, 1.5 and 2.5 mm (all p<0.001). The CC FD% was higher in circle 0.5, 1.5 and 2.5 mm (all p<0.001). Multivariate regression analysis showed that CC FD% in the circle 2.5 mm when the Z score ≥2 was associated with BCVA (β=9.08 (95% CI 3.96 to 14.20); p=0.005) and Z score (β=4.19 (95% CI 1.28 to 12.00); p=0.012). CONCLUSIONS Thinner ChT and a higher CC FD% were observed in children with MFS, and an increased CC FD% in circle 2.5 mm was significantly associated with worse BCVA and cardiac function. These findings may help identify future visual impairment and early cardiac events in MFS children.
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Affiliation(s)
- Kityee Ng
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, Guangdong, China
| | - Pusheng Xu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, Guangdong, China
| | - Guangming Jin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, Guangdong, China
| | - Weijing Cheng
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, Guangdong, China
| | - Xiaoling Luo
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, Guangdong, China
| | - Xiaoyan Ding
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, Guangdong, China
| | - Danying Zheng
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, Guangdong, China
| | - Yizhi Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, Guangdong, China
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Minnella AM, Centini C, Gambini G, Savastano MC, Pagliei V, Falsini B, Rizzo S, Ciasca G, Maceroni M. Choroidal Thickness Changes After Intravitreal Aflibercept Injections in Treatment-Naïve Neovascular AMD. Adv Ther 2022; 39:3248-3261. [PMID: 35597837 PMCID: PMC9239952 DOI: 10.1007/s12325-022-02129-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 03/14/2022] [Indexed: 11/29/2022]
Abstract
Introduction Choroidal thickness (CT) plays an important role in the pathogenesis of various ocular diseases, including neovascular age-related macular degeneration (nAMD). Previous studies evaluated the CT variations after anti-vascular endothelial growth factor (VEGF) injections in patients with nAMD, but the results are still controversial. The present study aimed to evaluate the CT at different times (15, 30, 60, 90, and 365 days) after intravitreal aflibercept injections and its correlation with the baseline CT in treatment-naïve patients with nAMD. Secondly, the study evaluated the correlation between CT variation at 365 days and the number of intravitreal injections received. Methods This was a prospective, open-label, single-arm pilot study. Twenty-one treatment-naïve nAMD eyes were enrolled. The study population underwent three monthly aflibercept injections (loading phase) and additional injections as needed (pro re nata regimen). A complete ophthalmological examination, including optical coherence tomography (OCT) was performed at each visit. CT was measured manually by two independent observers. All patients were evaluated at baseline and at 15, 30, 60, 90, and 365 days after the first intravitreal injection. Results CT showed a statistically significant reduction at days 15, 90, and 365 in comparison to baseline. However, the major reduction of CT was observed at day 15 and in eyes with a thicker choroid at baseline. No significant correlation between CT variation and the number of injections performed was found. Conclusion Our findings contribute to clarifying the role of aflibercept injections in choroidal vasculature, confirming its effect after the first 2 weeks. Moreover, CT can be considered as a potential biomarker, as it reflects the pharmacological effect of anti-VEGF drugs.
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Affiliation(s)
- Angelo Maria Minnella
- Università Cattolica del Sacro Cuore, Rome, Italy
- UOC Oftalmologia, Fondazione Policlinico Universitario A. Gemelli-IRCCS, Rome, Italy
| | | | - Gloria Gambini
- UOC Oftalmologia, Fondazione Policlinico Universitario A. Gemelli-IRCCS, Rome, Italy
| | - Maria Cristina Savastano
- Università Cattolica del Sacro Cuore, Rome, Italy
- UOC Oftalmologia, Fondazione Policlinico Universitario A. Gemelli-IRCCS, Rome, Italy
| | - Valeria Pagliei
- Dipartimento di biotecnologie e scienze cliniche applicate, Università de L’Aquila, L’Aquila, Italy
| | - Benedetto Falsini
- Università Cattolica del Sacro Cuore, Rome, Italy
- UOC Oftalmologia, Fondazione Policlinico Universitario A. Gemelli-IRCCS, Rome, Italy
| | - Stanislao Rizzo
- Università Cattolica del Sacro Cuore, Rome, Italy
- UOC Oftalmologia, Fondazione Policlinico Universitario A. Gemelli-IRCCS, Rome, Italy
| | - Gabriele Ciasca
- Università Cattolica del Sacro Cuore, Rome, Italy
- Fondazione Policlinico Universitario A. Gemelli-IRCCS, Largo Agostino Gemelli, 8, 00168 Rome, RM Italy
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In-vivo functional and structural retinal imaging using multiwavelength photoacoustic remote sensing microscopy. Sci Rep 2022; 12:4562. [PMID: 35296738 PMCID: PMC8927130 DOI: 10.1038/s41598-022-08508-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Accepted: 03/08/2022] [Indexed: 11/16/2022] Open
Abstract
Many important eye diseases as well as systemic disorders manifest themselves in the retina. Retinal imaging technologies are rapidly growing and can provide ever-increasing amounts of information about the structure, function, and molecular composition of retinal tissue in-vivo. Photoacoustic remote sensing (PARS) is a novel imaging modality based on all-optical detection of photoacoustic signals, which makes it suitable for a wide range of medical applications. In this study, PARS is applied for in-vivo imaging of the retina and estimating oxygen saturation in the retinal vasculature. To our knowledge, this is the first time that a non-contact photoacoustic imaging technique is applied for in-vivo imaging of the retina. Here, optical coherence tomography is also used as a well-established retinal imaging technique to navigate the PARS imaging beams and demonstrate the capabilities of the optical imaging setup. The system is applied for in-vivo imaging of both microanatomy and the microvasculature of the retina. The developed system has the potential to advance the understanding of the ocular environment and to help in monitoring of ophthalmic diseases.
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Rosenfeld PJ, Trivizki O, Gregori G, Wang RK. An Update on the Hemodynamic Model of Age-Related Macular Degeneration. Am J Ophthalmol 2022; 235:291-299. [PMID: 34509436 DOI: 10.1016/j.ajo.2021.08.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 08/22/2021] [Accepted: 08/30/2021] [Indexed: 12/26/2022]
Abstract
PURPOSE To provide an update on the hemodynamic model of age-related macular degeneration (AMD). DESIGN Evidence-based perspective. METHODS Review of the literature and experience of the authors. RESULTS Choroidal hemodynamics are not the primary cause of AMD as proposed by Ephraim Friedman in 1997. However, evidence is accumulating to suggest that choroidal perfusion is an important environmental influence that contributes to our understanding of disease progression in this complex genetic disorder. Although early and intermediate AMD seem to be influenced to a large extent by the underlying genetics, the asymmetry of disease progression to the later stages of AMD cannot be explained by genetics alone. The progression of disease and the asymmetry of this progression seem to correlate with abnormalities in choroidal perfusion that can be documented by optical coherence tomography. These perfusion abnormalities in the setting of a thickened Bruch's membrane are thought to exacerbate the impaired nutritional exchange between the retinal pigment epithelium and the choriocapillaris. We propose that the genetic susceptibility to develop AMD combined with age-related changes in macular choroidal hemodynamics, such as increasing choriocapillaris perfusion deficits and decreasing choroidal vascular densities, play an important role in disease progression and may help to explain the asymmetry between eyes, particularly in the later stages of AMD. CONCLUSIONS This updated hemodynamic model of AMD focuses on disease progression and highlights the importance of age-related changes in the choroidal circulation as a major environmental influence on disease severity in eyes that are genetically susceptible to develop AMD.
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Affiliation(s)
- Philip J Rosenfeld
- From the Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine (P.J.P., O.T., G.G.), Miami, Florida, USA.
| | - Omer Trivizki
- From the Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine (P.J.P., O.T., G.G.), Miami, Florida, USA; Department of Ophthalmology, Tel Aviv Medical Center, Tel Aviv University (O.T.), Tel Aviv, Israel and the Department of Bioengineering (R.K.W.) and Department of Ophthalmology, University of Washington, Seattle, Washington, USA
| | - Giovanni Gregori
- From the Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine (P.J.P., O.T., G.G.), Miami, Florida, USA
| | - Ruikang K Wang
- Department of Ophthalmology (R.K.W.), University of Washington, Seattle, Washington, USA
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Hibert M, Chen Y, Ohringer N, Feuer W, Waheed N, Heier J, Calhoun M, Rosenfeld P, Polimeni J. Altered Blood Flow in the Ophthalmic and Internal Carotid Arteries in Patients with Age-Related Macular Degeneration Measured Using Noncontrast MR Angiography at 7T. AJNR Am J Neuroradiol 2021; 42:1653-1660. [PMID: 34210664 PMCID: PMC8423057 DOI: 10.3174/ajnr.a7187] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 04/04/2021] [Indexed: 02/01/2023]
Abstract
BACKGROUND AND PURPOSE Age-related macular degeneration is associated with reduced perfusion of the eye; however, the role of altered blood flow in the upstream ophthalmic or internal carotid arteries is unclear. We used ultra-high-field MR imaging to investigate whether the diameter of and blood flow in the ophthalmic artery and/or the ICA are altered in age-related macular degeneration and whether any blood flow changes are associated with disease progression. MATERIALS AND METHODS Twenty-four patients with age-related macular degeneration and 13 similarly-aged healthy controls participated. TOF and high-resolution dynamic 2D phase-contrast MRA (0.26 × 0.26 × 2mm3, 100-ms effective sampling rate) was acquired at 7T. Vessel diameters were calculated from cross-sectional areas in phase-contrast acquisitions. Blood flow time-series were measured across the cardiac cycle. RESULTS The ophthalmic artery vessel diameter was found to be significantly smaller in patients with age-related macular degeneration than in controls. Volumetric flow through the ophthalmic artery was significantly lower in patients with late age-related macular degeneration, with a significant trend of decreasing volumetric ophthalmic artery flow rates with increasing disease severity. The resistance index was significantly greater in patients with age-related macular degeneration than in controls in the ophthalmic artery. Flow velocity through the ophthalmic artery and ICA was significantly higher in patients with age-related macular degeneration. Ophthalmic artery blood flow as a percentage of ipsilateral ICA blood flow was nearly double in controls than in patients with age-related macular degeneration. CONCLUSIONS These findings support the hypothesis that vascular changes upstream to the eye are associated with the severity of age-related macular degeneration. Additional investigation into the potential causality of this relationship and whether treatments that improve ocular circulation slow disease progression is warranted.
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Affiliation(s)
- M.L. Hibert
- From the Athinoula A. Martinos Center for Biomedical Imaging (M.L.H., Y.I.C., N. O., J.R.P.), Massachusetts General Hospital, Charlestown, Massachusetts
| | - Y.I. Chen
- From the Athinoula A. Martinos Center for Biomedical Imaging (M.L.H., Y.I.C., N. O., J.R.P.), Massachusetts General Hospital, Charlestown, Massachusetts,Department of Radiology (Y.I.C., J.R.P.), Harvard Medical School, Boston, Massachusetts
| | - N. Ohringer
- From the Athinoula A. Martinos Center for Biomedical Imaging (M.L.H., Y.I.C., N. O., J.R.P.), Massachusetts General Hospital, Charlestown, Massachusetts
| | - W.J. Feuer
- Department of Ophthalmology (W.J.F., P.J.R.), Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida
| | - N.K. Waheed
- New England Eye Center (N.K.W.), Tufts Medical Center, Boston, Massachusetts
| | - J.S. Heier
- Ophthalmic Consultants of Boston (J.S.H.), Boston, Massachusetts
| | | | - P.J. Rosenfeld
- Department of Ophthalmology (W.J.F., P.J.R.), Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida
| | - J.R. Polimeni
- From the Athinoula A. Martinos Center for Biomedical Imaging (M.L.H., Y.I.C., N. O., J.R.P.), Massachusetts General Hospital, Charlestown, Massachusetts,Department of Radiology (Y.I.C., J.R.P.), Harvard Medical School, Boston, Massachusetts,Harvard-Massachusetts Institute of Technology Division of Health Sciences and Technology (J.R.P.), Massachusetts Institute of Technology, Cambridge, Massachusetts
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Transcriptomic analysis of the mouse retina after acute and chronic normobaric and hypobaric hypoxia. Sci Rep 2021; 11:16666. [PMID: 34404875 PMCID: PMC8371159 DOI: 10.1038/s41598-021-96150-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 08/05/2021] [Indexed: 12/13/2022] Open
Abstract
Oxygen delivery to the retinal pigment epithelium and the outer retina is essential for metabolism, function, and survival of photoreceptors. Chronically reduced oxygen supply leads to retinal pathologies in patients and causes age-dependent retinal degeneration in mice. Hypoxia can result from decreased levels of inspired oxygen (normobaric hypoxia) or reduced barometric pressure (hypobaric hypoxia). Since the response of retinal cells to chronic normobaric or hypobaric hypoxia is mostly unknown, we examined the effect of six hypoxic conditions on the retinal transcriptome and photoreceptor morphology. Mice were exposed to short- and long-term normobaric hypoxia at 400 m or hypobaric hypoxia at 3450 m above sea level. Longitudinal studies over 11 weeks in normobaric hypoxia revealed four classes of genes that adapted differentially to the hypoxic condition. Seventeen genes were specifically regulated in hypobaric hypoxia and may affect the structural integrity of the retina, resulting in the shortening of photoreceptor segment length detected in various hypoxic groups. This study shows that retinal cells have the capacity to adapt to long-term hypoxia and that consequences of hypobaric hypoxia differ from those of normobaric hypoxia. Our datasets can be used as references to validate and compare retinal disease models associated with hypoxia.
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Corvi F, Sadda SR. Progression of geographic atrophy. EXPERT REVIEW OF OPHTHALMOLOGY 2021. [DOI: 10.1080/17469899.2021.1951231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Federico Corvi
- Doheny Eye Institute, United States, California, United States
- Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, California, United States
| | - SriniVas R. Sadda
- Doheny Eye Institute, United States, California, United States
- Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, California, United States
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Verticchio Vercellin AC, Harris A, Chiaravalli G, Sacco R, Siesky B, Ciulla T, Guidoboni G. Physics-based modeling of Age-related Macular Degeneration-A theoretical approach to quantify retinal and choroidal contributions to macular oxygenation. Math Biosci 2021; 339:108650. [PMID: 34197878 DOI: 10.1016/j.mbs.2021.108650] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 06/23/2021] [Accepted: 06/23/2021] [Indexed: 10/21/2022]
Abstract
We developed a mathematical model to characterize how macular oxygenation may be affected by abnormalities in the retinal and choroidal oxygen supplies. The macular region is modeled as a layered structure including: ganglion cell and nerve fiber layers, inner plexiform layer, inner nuclear layer, outer plexiform layer, outer nuclear layer, inner segment of photoreceptors layer and retinal pigmented epithelium. Each layer is characterized by specific levels of oxygen consumption. The vitreous and the choroid are located at the macula boundary and provide oxygen via boundary conditions of Dirichlet type. The three capillary plexi (superficial, intermediate, and deep) of the retinal circulation pierce the macular layers and provide oxygen via a volumetric source that depends on the retinal blood flow. Oxygen profiles through the macular tissue are calculated by simulating the balance among oxygen supply, consumption and diffusion in: (a) physiological baseline conditions; (b) retinal blood flow reduced by 10%, 30% and 50% with respect to baseline; (c) choroidal oxygen level diminished by 10%, 30% and 50% with respect to baseline. Model simulations predict that: (1) the oxygenation of the foveal avascular zone is not affected by reduction in retinal blood flow; (2) a reduction in choroidal oxygen supply significantly affects the outer layers, especially the photoreceptors and outer nuclear layers; (3) the impact of reduction in choroidal oxygen supply is larger in the region more proximal to the macular center; (4) the impact of reduction in retinal blood flow is larger in the region more proximal to the macular periphery. The proposed mathematical model suggests that changes in retinal and choroidal oxygen supplies impact the oxygenation of the macular tissue differentially. These results may help better understand the pathogenesis of macular degeneration.
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Affiliation(s)
| | - Alon Harris
- Department of Ophthalmology, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America.
| | - Greta Chiaravalli
- Italian Institute of Technology, Milano, Italy; Dipartimento di Fisica, Politecnico di Milano, Italy
| | - Riccardo Sacco
- Dipartimento di Matematica, Politecnico di Milano, Italy
| | - Brent Siesky
- Department of Ophthalmology, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America
| | - Thomas Ciulla
- Vitreoretinal Medicine and Surgery, Midwest Eye Institute, Indianapolis, IN 46290, United States of America
| | - Giovanna Guidoboni
- Department of Electrical Engineering and Computer Science, Department of Mathematics, University of Missouri, Columbia, MO, United States of America
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Abstract
This manuscript focuses on the pathogenesis of age-related maculopathy (ARM) and the documentation of new treatments in ARM. Ischaemia will be given special consideration, as it is believed to play a central role in both early ARM and late ARM or age-related macular degeneration (AMD). Reduced choroidal and retinal blood flow causes ischaemia of Bruch's membrane, retinal pigment epithelium and neuroretina in the early course of ARM. This is thought to be the primary trigger of the condition. Chronic ischaemia upregulates vascular endothelial growth factor (VEGF), which induces abnormal vessel growth in neovascular AMD. The role of ischaemia in neovascular AMD is supported by the evidence of effective new treatments targeting VEGF.
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Affiliation(s)
- Beatrix Feigl
- Institute of Health and Biomedical Innovation and School of Optometry, Queensland University of Technology, Brisbane, Australia.
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12
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Trinh M, Kalloniatis M, Nivison-Smith L. Radial Peripapillary Capillary Plexus Sparing and Underlying Retinal Vascular Impairment in Intermediate Age-Related Macular Degeneration. Invest Ophthalmol Vis Sci 2021; 62:2. [PMID: 33792619 PMCID: PMC8024775 DOI: 10.1167/iovs.62.4.2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Purpose To examine location-specific retinal vascular changes in intermediate age-related macular degeneration (iAMD) using age-matched, high-density en face optical coherence tomography angiography (OCTA) cluster analysis. Methods En face OCTA images of the 6 × 6 mm macular area were retrospectively acquired from 60 iAMD eyes and 60 age-matched normal eyes and then subdivided into 126 × 126 (47.62 × 47.62 µm) grids within the superficial and deep vascular complex. Grid-wise vessel perfusion (VP) were compared between iAMD and normal eyes from the corresponding 10-yearly age cohort, forming difference plots. Difference plots were further separated by normative topographical map spatial clusters (C1-6), derived from normaldatabase eyes (n = 236, 20–81 years old). Results Overall difference plots showed decreased VP in the superficial (−12.19%) and deep vascular complex (−6.44%) of iAMD compared to normal eyes (P < 0.0001 both comparisons). Cluster-based difference plots highlighted nonuniform changes in the superficial vascular complex, with sparing of VP at the nasal macula (corresponding to the radial peripapillary capillary plexus) versus decreased VP toward the temporal macula and foveal avascular zone (FAZ) (C1–6 all comparisons P < 0.0001, except C1 vs. C2P > 0.99 and C4 vs. C5P = 0.11). The deep vascular complex displayed diffusely decreased VP, greater at the FAZ (P < 0.0001). Conclusions High-density en face OCTA cluster analysis suggests relative sparing of the radial peripapillary capillary plexus and impairment of underlying retinal vasculature, supporting potential anterograde transsynaptic degeneration in iAMD. These location-specific data may better guide future diagnostic and management protocol of iAMD.
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Affiliation(s)
- Matt Trinh
- Centre for Eye Health, University of New South Wales, Sydney, Australia.,School of Optometry and Vision Science, University of New South Wales, Sydney, Australia
| | - Michael Kalloniatis
- Centre for Eye Health, University of New South Wales, Sydney, Australia.,School of Optometry and Vision Science, University of New South Wales, Sydney, Australia
| | - Lisa Nivison-Smith
- Centre for Eye Health, University of New South Wales, Sydney, Australia.,School of Optometry and Vision Science, University of New South Wales, Sydney, Australia
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Corvi F, Cozzi M, Corradetti G, Staurenghi G, Sarraf D, Sadda SR. Quantitative assessment of choriocapillaris flow deficits in eyes with macular neovascularization. Graefes Arch Clin Exp Ophthalmol 2021; 259:1811-1819. [PMID: 33417089 DOI: 10.1007/s00417-020-05056-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 12/09/2020] [Accepted: 12/16/2020] [Indexed: 11/27/2022] Open
Abstract
PURPOSE To investigate choriocapillaris flow deficits (CC FD) in a group of eyes with Type 3 macular neovascularization (MNV) versus a group of eyes with Type 1 and/or 2 MNV versus healthy eyes. METHODS In this cross-sectional, retrospective, multicenter, observational study, consecutive patients with Type 3 MNV, Type 1 and/or 2 MNV, and age-matched controls were included. PLEX Elite optical coherence tomography angiography was performed with a 6 × 6 mm scan pattern centered on the fovea. The CC FD was computed in 4 peripheral 1 × 1 mm squares to allow comparison between equidistant regions unaffected by MNV. RESULTS Twenty Type 3, 20 Type 1 and/or 2 MNV [13 (65%) Type 1 MNV, 1 (5%) Type 2 MNV, and 6 (30%) mixed Type 1 and 2 MNV], and 20 age-matched controls were included. The mean impairment in the CC in the 4 peripheral squares was 16.07 ± 7.27% in Type 3 MNV eyes, 11.48 ± 5.59% in Type 1/2 MNV eyes, and 9.64 ± 3.59% in controls. Type 3 MNV displayed a statistically significantly higher CC FD compared with both Type 1/2 MNV (P = 0.031) and controls (P < 0.0001). No significant differences were observed between Type 1/2 MNV and controls (P = 0.223). CONCLUSIONS CC FD was significantly greater in the peripheral macular regions of eyes with Type 3 MNV compared to eyes with Type 1/2 MNV and normal control eyes. Pathogenic choroidal mechanisms may differ in eyes with different MNV subtypes. Whereas focal CC impairment may drive the development of Type 1/2 MNV, diffuse CC disruption may be more important in eyes with Type 3 MNV.
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Affiliation(s)
- Federico Corvi
- Doheny Eye Institute, Los Angeles, CA, USA
- Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
- Eye Clinic, Department of Biomedical and Clinical Science "Luigi Sacco", Sacco Hospital, University of Milan, Milan, Italy
| | - Mariano Cozzi
- Eye Clinic, Department of Biomedical and Clinical Science "Luigi Sacco", Sacco Hospital, University of Milan, Milan, Italy
| | - Giulia Corradetti
- Doheny Eye Institute, Los Angeles, CA, USA
- Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Giovanni Staurenghi
- Eye Clinic, Department of Biomedical and Clinical Science "Luigi Sacco", Sacco Hospital, University of Milan, Milan, Italy
| | - David Sarraf
- Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
- Greater Los Angeles VA Healthcare Center, Los Angeles, CA, USA
| | - SriniVas R Sadda
- Doheny Eye Institute, Los Angeles, CA, USA.
- Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
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14
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Gao L, Wang J, You Q, Guo Y, Flaxel CJ, Hwang TS, Huang D, Jia Y, Bailey ST. Plexus-specific retinal capillary avascular area in exudative age-related macular degeneration with projection-resolved OCT angiography. Br J Ophthalmol 2020; 106:719-723. [PMID: 33355172 DOI: 10.1136/bjophthalmol-2020-317562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 12/02/2020] [Accepted: 12/08/2020] [Indexed: 11/04/2022]
Abstract
OBJECTIVE To detect the plexus-specific retinal capillary avascular area in exudative age-related macular degeneration (EAMD) with projection-resolved optical coherence tomography angiography (PR-OCTA). METHODS AND ANALYSIS In this prospective cross-sectional single centre study, eyes with treatment-naïve EAMD underwent macular 3×3 mm OCTA with AngioVue system. OCTA scans were analysed and processed including three-dimensional projection artefact removal, retinal layer semi-automated segmentation and en face angiogram generation. Automated quantification of extrafoveal (excluding the central 1 mm circle) avascular area (EAA) were calculated on projection-resolved superficial vascular complex (SVC), intermediate capillary plexus (ICP) and deep capillary plexus (DCP), respectively. RESULTS Nineteen eyes with EAMD and 19 age-matched healthy control eyes were included. There was no significant difference between the EAMD and control eyes in terms of age, sex, axial length and mean ocular perfusion pressure (all p>0.05). Compared with control eyes, EAMD eyes had significantly larger EAA in SVC (median 0.125 vs 0.059 mm2, p=0.006), ICP (0.016 vs 0.000 mm2, p=0.004) and DCP (0.033 vs 0.000 mm2, p<0.001). CONCLUSION PR-OCTA showed that EAMD is associated with focal avascular area in all the three retinal vascular plexuses.
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Affiliation(s)
- Liqin Gao
- Ophthalmology, Beijing Tongren Eye Center, Beijing, China
| | - Jie Wang
- Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, USA
| | - Qisheng You
- Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, USA
| | - Yukun Guo
- Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, USA
| | - Christina J Flaxel
- Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, USA
| | - Thomas S Hwang
- Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, USA
| | - David Huang
- Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, USA
| | - Yali Jia
- Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, USA
| | - Steven T Bailey
- Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, USA
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15
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Lipecz A, Miller L, Kovacs I, Czakó C, Csipo T, Baffi J, Csiszar A, Tarantini S, Ungvari Z, Yabluchanskiy A, Conley S. Microvascular contributions to age-related macular degeneration (AMD): from mechanisms of choriocapillaris aging to novel interventions. GeroScience 2019; 41:813-845. [PMID: 31797238 PMCID: PMC6925092 DOI: 10.1007/s11357-019-00138-3] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 11/12/2019] [Indexed: 12/13/2022] Open
Abstract
Aging of the microcirculatory network plays a central role in the pathogenesis of a wide range of age-related diseases, from heart failure to Alzheimer's disease. In the eye, changes in the choroid and choroidal microcirculation (choriocapillaris) also occur with age, and these changes can play a critical role in the pathogenesis of age-related macular degeneration (AMD). In order to develop novel treatments for amelioration of choriocapillaris aging and prevention of AMD, it is essential to understand the cellular and functional changes that occur in the choroid and choriocapillaris during aging. In this review, recent advances in in vivo analysis of choroidal structure and function in AMD patients and patients at risk for AMD are discussed. The pathophysiological roles of fundamental cellular and molecular mechanisms of aging including oxidative stress, mitochondrial dysfunction, and impaired resistance to molecular stressors in the choriocapillaris are also considered in terms of their contribution to the pathogenesis of AMD. The pathogenic roles of cardiovascular risk factors that exacerbate microvascular aging processes, such as smoking, hypertension, and obesity as they relate to AMD and choroid and choriocapillaris changes in patients with these cardiovascular risk factors, are also discussed. Finally, future directions and opportunities to develop novel interventions to prevent/delay AMD by targeting fundamental cellular and molecular aging processes are presented.
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Affiliation(s)
- Agnes Lipecz
- Translational Geroscience Laboratory, Center for Geroscience and Healthy Brain Aging/Reynolds Oklahoma Center on Aging, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Vascular Cognitive Impairment and Neurodegeneration Program, Center for Geroscience and Healthy Brain Aging/Reynolds Oklahoma Center on Aging, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Department of Ophthalmology, Josa Andras Hospital, Nyiregyhaza, Hungary
- International Training Program in Geroscience, Doctoral School of Basic and Translational Medicine/Department of Public Health, Semmelweis University, Budapest, Hungary
- Department of Ophthalmology, Semmelweis University, Budapest, Hungary
| | - Lauren Miller
- Vascular Cognitive Impairment and Neurodegeneration Program, Center for Geroscience and Healthy Brain Aging/Reynolds Oklahoma Center on Aging, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Department of Cell Biology, University of Oklahoma Health Sciences Center, 940 Stanton L. Young Blvd. BMSB553, Oklahoma City, OK, 73104, USA
| | - Illes Kovacs
- Vascular Cognitive Impairment and Neurodegeneration Program, Center for Geroscience and Healthy Brain Aging/Reynolds Oklahoma Center on Aging, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Department of Ophthalmology, Semmelweis University, Budapest, Hungary
- Department of Ophthalmology, Weill Cornell Medical College, New York City, NY, USA
| | - Cecília Czakó
- Department of Ophthalmology, Semmelweis University, Budapest, Hungary
| | - Tamas Csipo
- Translational Geroscience Laboratory, Center for Geroscience and Healthy Brain Aging/Reynolds Oklahoma Center on Aging, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Vascular Cognitive Impairment and Neurodegeneration Program, Center for Geroscience and Healthy Brain Aging/Reynolds Oklahoma Center on Aging, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- International Training Program in Geroscience, Doctoral School of Basic and Translational Medicine/Department of Public Health, Semmelweis University, Budapest, Hungary
- International Training Program in Geroscience, Division of Clinical Physiology, Department of Cardiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Judit Baffi
- Vascular Cognitive Impairment and Neurodegeneration Program, Center for Geroscience and Healthy Brain Aging/Reynolds Oklahoma Center on Aging, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Anna Csiszar
- Translational Geroscience Laboratory, Center for Geroscience and Healthy Brain Aging/Reynolds Oklahoma Center on Aging, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Vascular Cognitive Impairment and Neurodegeneration Program, Center for Geroscience and Healthy Brain Aging/Reynolds Oklahoma Center on Aging, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- International Training Program in Geroscience, Doctoral School of Basic and Translational Medicine/Department of Public Health, Semmelweis University, Budapest, Hungary
- International Training Program in Geroscience, Theoretical Medicine Doctoral School, University of Szeged, Szeged, Hungary
| | - Stefano Tarantini
- Translational Geroscience Laboratory, Center for Geroscience and Healthy Brain Aging/Reynolds Oklahoma Center on Aging, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Vascular Cognitive Impairment and Neurodegeneration Program, Center for Geroscience and Healthy Brain Aging/Reynolds Oklahoma Center on Aging, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- International Training Program in Geroscience, Doctoral School of Basic and Translational Medicine/Department of Public Health, Semmelweis University, Budapest, Hungary
- International Training Program in Geroscience, Theoretical Medicine Doctoral School, University of Szeged, Szeged, Hungary
| | - Zoltan Ungvari
- Translational Geroscience Laboratory, Center for Geroscience and Healthy Brain Aging/Reynolds Oklahoma Center on Aging, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Vascular Cognitive Impairment and Neurodegeneration Program, Center for Geroscience and Healthy Brain Aging/Reynolds Oklahoma Center on Aging, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- International Training Program in Geroscience, Doctoral School of Basic and Translational Medicine/Department of Public Health, Semmelweis University, Budapest, Hungary
- International Training Program in Geroscience, Theoretical Medicine Doctoral School, University of Szeged, Szeged, Hungary
- Department of Health Promotion Sciences, College of Public Health, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Andriy Yabluchanskiy
- Translational Geroscience Laboratory, Center for Geroscience and Healthy Brain Aging/Reynolds Oklahoma Center on Aging, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Vascular Cognitive Impairment and Neurodegeneration Program, Center for Geroscience and Healthy Brain Aging/Reynolds Oklahoma Center on Aging, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Shannon Conley
- Vascular Cognitive Impairment and Neurodegeneration Program, Center for Geroscience and Healthy Brain Aging/Reynolds Oklahoma Center on Aging, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
- Department of Cell Biology, University of Oklahoma Health Sciences Center, 940 Stanton L. Young Blvd. BMSB553, Oklahoma City, OK, 73104, USA.
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16
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Alagorie AR, Verma A, Nassisi M, Sadda SR. Quantitative Assessment of Choriocapillaris Flow Deficits in Eyes with Advanced Age-Related Macular Degeneration Versus Healthy Eyes. Am J Ophthalmol 2019; 205:132-139. [PMID: 31078531 DOI: 10.1016/j.ajo.2019.04.037] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 04/15/2019] [Accepted: 04/17/2019] [Indexed: 12/20/2022]
Abstract
PURPOSE To compare choriocapillaris (CC) flow deficits in eyes with geographic atrophy (GA) or choroidal neovascularization (CNV) associated with age-related macular degeneration (AMD) and age-matched healthy control subjects. DESIGN Cross-sectional study. METHODS Patients with GA due to AMD, CNV due to AMD, and age-matched healthy subjects presenting to the Doheny-UCLA Eye Centers were enrolled in this cross-sectional institutional review board-approved study. Swept-source optical coherence tomography angiography was performed using a Zeiss PLEX Elite instrument with a 6 × 6-mm scan pattern centered on the fovea. Two repeated volume scans were acquired to allow for image averaging. The instrument predefined en face slab of the CC was used to isolate and display the CC. Both the structural and optical coherence tomography angiography slabs from this location were exported for averaging and signal compensation using Image J. The resultant image was then binarized. The CC flow deficit percentage (FD%) was computed in 4 peripheral 1 × 1-mm squares located at the corners of the images to allow comparison between equidistant regions unaffected by atrophy or CNV. RESULTS Twenty eyes of 20 subjects were enrolled in each of the 3 groups (CNV, GA, normal) for this study. The average CC FD% of the 4 peripheral squares was 17.24% ± 2.86% in GA eyes, 15.55% ± 1.03% in CNV eyes, and 15.31% ± 0.93% in healthy controls of a similar age. The FD% in GA eyes was significantly greater than in both normal eyes and eyes with CNV (p= 0.012 and 0.038 respectively). The difference in FD% was not significantly different between CNV eyes and normal eyes for the tested peripheral macular regions (P = .678). CONCLUSIONS The CC in peripheral macular regions in eyes with GA shows greater impairment than in eyes with CNV.
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17
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Wang D, Haytham A, Mayo L, Tao Y, Saeedi O. Automated retinal microvascular velocimetry based on erythrocyte mediated angiography. BIOMEDICAL OPTICS EXPRESS 2019; 10:3681-3697. [PMID: 31360609 PMCID: PMC6640827 DOI: 10.1364/boe.10.003681] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 06/13/2019] [Accepted: 06/17/2019] [Indexed: 05/13/2023]
Abstract
Retinal blood flow is an emerging biomarker in ocular and systemic disease. Erythrocyte mediated angiography (EMA) is a novel technique that provides an easily interpretable blood flow velocity quantification by directly tracing individual moving erythrocyte ghosts over time in vivo, imaged using a scanning laser ophthalmoscope (Heidelberg Retina Angiograph platform). This tracking procedure, however, requires time-consuming manual analysis to determine blood flow. To overcome this current bottleneck, we developed an objective and automated velocimetry approach, EMA - Automated Velocimetry (EMA-AV), which is based on a modified sequential Monte Carlo method. The intra-class correlation coefficient (ICC) between trained human graders and EMA-AV is 0.98 for mean vessel velocity estimation and 0.92 for frame by frame erythrocyte velocity estimation. This study proves EMA-AV is a reliable tool for quantification of retinal microvascular velocity and flow and establishes EMA-AV as a reliable and interpretable tool for quantifying retinal microvascular velocity.
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Affiliation(s)
- Dongyi Wang
- Bio-Imaging and Machine Vision Lab, Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742,
USA
| | - Ayman Haytham
- Aureus University School of Medicine, Wayaca 31C, Oranjestad,
Aruba
| | - Lakyn Mayo
- Department of Ophthalmology and Visual Sciences, University of Maryland School of Medicine, 419 W Redwood Street, Suite 470, Baltimore, MD 21201,
USA
| | - Yang Tao
- Bio-Imaging and Machine Vision Lab, Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742,
USA
| | - Osamah Saeedi
- Department of Ophthalmology and Visual Sciences, University of Maryland School of Medicine, 419 W Redwood Street, Suite 470, Baltimore, MD 21201,
USA
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18
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Lee B, Ahn J, Yun C, Kim SW, Oh J. Variation of Retinal and Choroidal Vasculatures in Patients With Age-Related Macular Degeneration. ACTA ACUST UNITED AC 2018; 59:5246-5255. [DOI: 10.1167/iovs.17-23600] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Boram Lee
- Department of Ophthalmology, Korea University College of Medicine, Seoul, Korea
| | - Jaemoon Ahn
- Department of Ophthalmology, Korea University College of Medicine, Seoul, Korea
| | - Cheolmin Yun
- Department of Ophthalmology, Korea University College of Medicine, Seoul, Korea
| | - Seong-woo Kim
- Department of Ophthalmology, Korea University College of Medicine, Seoul, Korea
| | - Jaeryung Oh
- Department of Ophthalmology, Korea University College of Medicine, Seoul, Korea
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19
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Robinson DG, Margrain TH, Dunn MJ, Bailey C, Binns AM. Low-Level Nighttime Light Therapy for Age-Related Macular Degeneration: A Randomized Clinical Trial. ACTA ACUST UNITED AC 2018; 59:4531-4541. [DOI: 10.1167/iovs.18-24284] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- D. Grant Robinson
- School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom
| | - Tom H. Margrain
- School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom
| | - Matt J. Dunn
- School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom
| | - Clare Bailey
- Bristol Eye Hospital, Lower Maudlin Street, Bristol, United Kingdom
| | - Alison M. Binns
- Division of Optometry and Visual Science, School of Health Sciences, City, University of London, United Kingdom
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20
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Wei X, Balne PK, Meissner KE, Barathi VA, Schmetterer L, Agrawal R. Assessment of flow dynamics in retinal and choroidal microcirculation. Surv Ophthalmol 2018; 63:646-664. [DOI: 10.1016/j.survophthal.2018.03.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 03/19/2018] [Accepted: 03/19/2018] [Indexed: 01/08/2023]
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21
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Hif1a inactivation rescues photoreceptor degeneration induced by a chronic hypoxia-like stress. Cell Death Differ 2018; 25:2071-2085. [PMID: 29666476 PMCID: PMC6261999 DOI: 10.1038/s41418-018-0094-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 02/13/2018] [Accepted: 02/21/2018] [Indexed: 12/11/2022] Open
Abstract
Reduced choroidal blood flow and tissue changes in the ageing human eye impair oxygen delivery to photoreceptors and the retinal pigment epithelium. As a consequence, mild but chronic hypoxia may develop and disturb cell metabolism, function and ultimately survival, potentially contributing to retinal pathologies such as age-related macular degeneration (AMD). Here, we show that several hypoxia-inducible genes were expressed at higher levels in the aged human retina suggesting increased activity of hypoxia-inducible transcription factors (HIFs) during the physiological ageing process. To model chronically elevated HIF activity and investigate ensuing consequences for photoreceptors, we generated mice lacking von Hippel Lindau (VHL) protein in rods. This activated HIF transcription factors and led to a slowly progressing retinal degeneration in the ageing mouse retina. Importantly, this process depended mainly on HIF1 with only a minor contribution of HIF2. A gene therapy approach using AAV-mediated RNA interference through an anti-Hif1a shRNA significantly mitigated the degeneration suggesting a potential intervention strategy that may be applicable to human patients.
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22
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Barben M, Schori C, Samardzija M, Grimm C. Targeting Hif1a rescues cone degeneration and prevents subretinal neovascularization in a model of chronic hypoxia. Mol Neurodegener 2018. [PMID: 29514656 PMCID: PMC5842520 DOI: 10.1186/s13024-018-0243-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Background Degeneration of cone photoreceptors leads to loss of vision in patients suffering from age-related macular degeneration (AMD) and other cone dystrophies. Evidence, such as choroidal ischemia and decreased choroidal blood flow, implicates reduced tissue oxygenation in AMD pathology and suggests a role of the cellular response to hypoxia in disease onset and progression. Such a chronic hypoxic situation may promote several cellular responses including stabilization of hypoxia-inducible factors (HIFs). Methods To investigate the consequence of a chronic activation of the molecular response to hypoxia in cones, von Hippel Lindau protein (VHL) was specifically ablated in cones of the all-cone R91W;Nrl-/- mouse. Retinal function and morphology was evaluated by ERG and light microscopy, while differential gene expression was tested by real-time PCR. Retinal vasculature was analyzed by immunostainings and fluorescein angiography. Two-way ANOVA with Šídák’s multiple comparison test was performed for statistical analysis. Results Cone-specific ablation of Vhl resulted in stabilization and activation of hypoxia-inducible factor 1A (HIF1A) which led to increased expression of genes associated with hypoxia and retinal stress. Our data demonstrate severe cone degeneration and pathologic vessel growth, features that are central to AMD pathology. Subretinal neovascularization was accompanied by vascular leakage and infiltration of microglia cells. Interestingly, we observed increased expression of tissue inhibitor of metalloproteinase 3 (Timp3) during the aging process, a gene associated with AMD and Bruch’s membrane integrity. Additional deletion of Hif1a protected cone cells, prevented pathological vessel growth and preserved vision. Conclusions Our data provide evidence for a HIF1A-mediated mechanism leading to pathological vessel growth and cone degeneration in response to a chronic hypoxia-like situation. Consequently, our results identify HIF1A as a potential therapeutic target to rescue hypoxia-related vision loss in patients.
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Affiliation(s)
- Maya Barben
- Laboratory for Retinal Cell Biology, Department of Ophthalmology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.,Neuroscience Center Zurich (ZNZ), University of Zurich, Zurich, Switzerland
| | - Christian Schori
- Laboratory for Retinal Cell Biology, Department of Ophthalmology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.,Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | - Marijana Samardzija
- Laboratory for Retinal Cell Biology, Department of Ophthalmology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
| | - Christian Grimm
- Laboratory for Retinal Cell Biology, Department of Ophthalmology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.,Neuroscience Center Zurich (ZNZ), University of Zurich, Zurich, Switzerland.,Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
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23
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Dieguez HH, Romeo HE, González Fleitas MF, Aranda ML, Milne GA, Rosenstein RE, Dorfman D. Superior cervical gangliectomy induces non-exudative age-related macular degeneration in mice. Dis Model Mech 2018; 11:dmm.031641. [PMID: 29361515 PMCID: PMC5894943 DOI: 10.1242/dmm.031641] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 11/28/2017] [Indexed: 12/20/2022] Open
Abstract
Non-exudative age-related macular degeneration, a prevalent cause of blindness, is a progressive and degenerative disease characterized by alterations in Bruch's membrane, retinal pigment epithelium, and photoreceptors exclusively localized in the macula. Although experimental murine models exist, the vast majority take a long time to develop retinal alterations and, in general, these alterations are ubiquitous, with many resulting from non-eye-specific genetic manipulations; additionally, most do not always reproduce the hallmarks of human age-related macular degeneration. Choroid vessels receive sympathetic innervation from the superior cervical ganglion, which, together with the parasympathetic system, regulates blood flow into the choroid. Choroid blood flow changes have been involved in age-related macular degeneration development and progression. At present, no experimental models take this factor into account. The aim of this work was to analyze the effect of superior cervical gangliectomy (also known as ganglionectomy) on the choroid, Bruch's membrane, retinal pigment epithelium and retina. Adult male C57BL/6J mice underwent unilateral superior cervical gangliectomy and a contralateral sham procedure. Although superior cervical gangliectomy induced ubiquitous choroid and choriocapillaris changes, it induced Bruch's membrane thickening, loss of retinal pigment epithelium melanin content and retinoid isomerohydrolase, the appearance of drusen-like deposits, and retinal pigment epithelium and photoreceptor atrophy, exclusively localized in the temporal side. Moreover, superior cervical gangliectomy provoked a localized increase in retinal pigment epithelium and photoreceptor apoptosis, and a decline in photoreceptor electroretinographic function. Therefore, superior cervical gangliectomy recapitulated the main features of human non-exudative age-related macular degeneration, and could become a new experimental model of dry age-related macular degeneration, and a useful platform for developing new therapies. Summary: Ubiquitous alteration of choroid circulation causes localized retinal alterations in mice that are similar to human non-exudative age-related macular degeneration, thus providing a new potential experimental model of the disease.
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Affiliation(s)
- Hernán H Dieguez
- Laboratory of Retinal Neurochemistry and Experimental Ophthalmology, Department of Human Biochemistry, School of Medicine/CEFyBO, University of Buenos Aires/CONICET, Buenos Aires C1121ABG, Argentina
| | - Horacio E Romeo
- Faculty of Medical Sciences, Pontifical Catholic University of Argentina, BIOMED/UCA/CONICET, Buenos Aires C1107AFB, Argentina
| | - María F González Fleitas
- Laboratory of Retinal Neurochemistry and Experimental Ophthalmology, Department of Human Biochemistry, School of Medicine/CEFyBO, University of Buenos Aires/CONICET, Buenos Aires C1121ABG, Argentina
| | - Marcos L Aranda
- Laboratory of Retinal Neurochemistry and Experimental Ophthalmology, Department of Human Biochemistry, School of Medicine/CEFyBO, University of Buenos Aires/CONICET, Buenos Aires C1121ABG, Argentina
| | - Georgia A Milne
- Laboratory of Retinal Neurochemistry and Experimental Ophthalmology, Department of Human Biochemistry, School of Medicine/CEFyBO, University of Buenos Aires/CONICET, Buenos Aires C1121ABG, Argentina
| | - Ruth E Rosenstein
- Laboratory of Retinal Neurochemistry and Experimental Ophthalmology, Department of Human Biochemistry, School of Medicine/CEFyBO, University of Buenos Aires/CONICET, Buenos Aires C1121ABG, Argentina
| | - Damián Dorfman
- Laboratory of Retinal Neurochemistry and Experimental Ophthalmology, Department of Human Biochemistry, School of Medicine/CEFyBO, University of Buenos Aires/CONICET, Buenos Aires C1121ABG, Argentina
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24
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Linsenmeier RA, Zhang HF. Retinal oxygen: from animals to humans. Prog Retin Eye Res 2017; 58:115-151. [PMID: 28109737 DOI: 10.1016/j.preteyeres.2017.01.003] [Citation(s) in RCA: 143] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 01/13/2017] [Accepted: 01/17/2017] [Indexed: 10/20/2022]
Abstract
This article discusses retinal oxygenation and retinal metabolism by focusing on measurements made with two of the principal methods used to study O2 in the retina: measurements of PO2 with oxygen-sensitive microelectrodes in vivo in animals with a retinal circulation similar to that of humans, and oximetry, which can be used non-invasively in both animals and humans to measure O2 concentration in retinal vessels. Microelectrodes uniquely have high spatial resolution, allowing the mapping of PO2 in detail, and when combined with mathematical models of diffusion and consumption, they provide information about retinal metabolism. Mathematical models, grounded in experiments, can also be used to simulate situations that are not amenable to experimental study. New methods of oximetry, particularly photoacoustic ophthalmoscopy and visible light optical coherence tomography, provide depth-resolved methods that can separate signals from blood vessels and surrounding tissues, and can be combined with blood flow measures to determine metabolic rate. We discuss the effects on retinal oxygenation of illumination, hypoxia and hyperoxia, and describe retinal oxygenation in diabetes, retinal detachment, arterial occlusion, and macular degeneration. We explain how the metabolic measurements obtained from microelectrodes and imaging are different, and how they need to be brought together in the future. Finally, we argue for revisiting the clinical use of hyperoxia in ophthalmology, particularly in retinal arterial occlusions and retinal detachment, based on animal research and diffusion theory.
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Affiliation(s)
- Robert A Linsenmeier
- Biomedical Engineering Department, Northwestern University, 2145 Sheridan Road, Evanston 60208-3107, IL, USA; Neurobiology Department, Northwestern University, 2205 Tech Drive, Evanston 60208-3520, IL, USA; Ophthalmology Department, Northwestern University, 645 N. Michigan Ave, Suite 440, Chicago 60611, IL, USA.
| | - Hao F Zhang
- Biomedical Engineering Department, Northwestern University, 2145 Sheridan Road, Evanston 60208-3107, IL, USA; Ophthalmology Department, Northwestern University, 645 N. Michigan Ave, Suite 440, Chicago 60611, IL, USA.
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Moult EM, Choi W, Boas DA, Baumann B, Clermont AC, Feener EP, Fujimoto JG. Evaluating anesthetic protocols for functional blood flow imaging in the rat eye. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:16005. [PMID: 28056146 PMCID: PMC5217081 DOI: 10.1117/1.jbo.22.1.016005] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 12/15/2016] [Indexed: 05/27/2023]
Abstract
The purpose of this study is to evaluate the suitability of five different anesthetic protocols (isoflurane, isoflurane–xylazine, pentobarbital, ketamine–xylazine, and ketamine–xylazine–vecuronium) for functional blood flow imaging in the rat eye. Total retinal blood flow was measured at a series of time points using an ultrahigh-speed Doppler OCT system. Additionally, each anesthetic protocol was qualitatively evaluated according to the following criteria: (1) time-stability of blood flow, (2) overall rate of blood flow, (3) ocular immobilization, and (4) simplicity. We observed that different anesthetic protocols produced markedly different blood flows. Different anesthetic protocols also varied with respect to the four evaluated criteria. These findings suggest that the choice of anesthetic protocol should be carefully considered when designing and interpreting functional blood flow studies in the rat eye.
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Affiliation(s)
- Eric M. Moult
- Massachusetts Institute of Technology, Research Laboratory of Electronics, Department of Electrical Engineering and Computer Science, 50 Vassar Street, Cambridge 02139, United States
| | - WooJhon Choi
- Massachusetts Institute of Technology, Research Laboratory of Electronics, Department of Electrical Engineering and Computer Science, 50 Vassar Street, Cambridge 02139, United States
| | - David A. Boas
- Harvard Medical School, Massachusetts General Hospital, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, 13th Street, Charlestown 02129, United States
| | - Bernhard Baumann
- Massachusetts Institute of Technology, Research Laboratory of Electronics, Department of Electrical Engineering and Computer Science, 50 Vassar Street, Cambridge 02139, United States
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Waehringer Guertel 18, Vienna 1090, Austria
| | - Allen C. Clermont
- Joslin Diabetes Center, Research Division, One Joslin Place, Boston 02215, United States
| | - Edward P. Feener
- Joslin Diabetes Center, Research Division, One Joslin Place, Boston 02215, United States
| | - James G. Fujimoto
- Massachusetts Institute of Technology, Research Laboratory of Electronics, Department of Electrical Engineering and Computer Science, 50 Vassar Street, Cambridge 02139, United States
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Maslov MY, Chernysheva GA, Smol'jakova VI, Aliev OI, Kolosova NG, Plotnikov MB. Hemorheological parameters and their correlations in OXYS rats: a new model of hyperviscosity syndrome. Clin Hemorheol Microcirc 2016; 60:405-11. [PMID: 25062716 DOI: 10.3233/ch-141860] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Rheohaemapheresis aims to normalize major rheological parameters and is used to treat patients with dry age-related macular degeneration (AMD). While effective, this approach is invasive and requires specially trained personnel. Therefore, the search for novel effective compounds with hemorheological properties that can be taken orally to treat AMD is justified. The use of a robust rodent model of AMD with high blood viscosity is crucial to test the efficacy of potential hemorheological drugs to treat this disease. The objective of this study was to investigate whether OXYS rats, generally used as an animal model of AMD, have hyperviscosity syndrome. The results of this study show that blood viscosity in OXYS rats at low (3-10 s -1) and high (45-300 s -1) shear rates were 14-20% and 7-10% higher than in Wistar rats, while hematocrit and plasma viscosity were not different. Red blood cells (RBCs) in OXYS rats were more prone to aggregation as shown by 39% shorter half-time than in Wistar rats. RBCs were also more rigid in OXYS than in Wistar rats as shown by 21-33% lower index of elongation at the shear stress of 1-7 Pa. These data indicate that OXYS rats have hyperviscosity syndrome as the result of abnormal RBC deformability and aggregation. We propose to use OXYS rats as an animal model for preclinical studies to test compounds with hemorheological properties aimed to treat AMD.
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Affiliation(s)
- Mikhail Y Maslov
- Steward St. Elizabeth's Medical Center/Tufts University School of Medicine, Department of Anesthesiology, Critical Care, and Pain Medicine, Boston, MA, USA
| | - Galina A Chernysheva
- E.D. Goldberg Institute of Pharmacology, Russian Academy of Medical Sciences, Tomsk, Russia
| | - Vera I Smol'jakova
- E.D. Goldberg Institute of Pharmacology, Russian Academy of Medical Sciences, Tomsk, Russia
| | - Oleg I Aliev
- E.D. Goldberg Institute of Pharmacology, Russian Academy of Medical Sciences, Tomsk, Russia.,Tomsk State University, Tomsk, Russia
| | - Natalia G Kolosova
- Institute of Cytology and Genetics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
| | - Mark B Plotnikov
- E.D. Goldberg Institute of Pharmacology, Russian Academy of Medical Sciences, Tomsk, Russia.,Tomsk State University, Tomsk, Russia
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Form, shape and function: segmented blood flow in the choriocapillaris. Sci Rep 2016; 6:35754. [PMID: 27779198 PMCID: PMC5078844 DOI: 10.1038/srep35754] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 10/05/2016] [Indexed: 11/29/2022] Open
Abstract
The development of fluid transport systems was a key event in the evolution of animals and plants. While within vertebrates branched geometries predominate, the choriocapillaris, which is the microvascular bed that is responsible for the maintenance of the outer retina, has evolved a planar topology. Here we examine the flow and mass transfer properties associated with this unusual geometry. We show that as a result of the form of the choriocapillaris, the blood flow is decomposed into a tessellation of functional vascular segments of various shapes delineated by separation surfaces across which there is no flow, and in the vicinity of which the transport of passive substances is diffusion-limited. The shape of each functional segment is determined by the distribution of arterioles and venules and their respective relative flow rates. We also show that, remarkably, the mass exchange with the outer retina is a function of the shape of each functional segment. In addition to introducing a novel framework in which the structure and function of the metabolite delivery system to the outer retina may be investigated in health and disease, the present work provides a general characterisation of the flow and transfers in multipole Hele-Shaw configurations.
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Toto L, Borrelli E, Mastropasqua R, Di Antonio L, Doronzo E, Carpineto P, Mastropasqua L. Association between outer retinal alterations and microvascular changes in intermediate stage age-related macular degeneration: an optical coherence tomography angiography study. Br J Ophthalmol 2016; 101:774-779. [DOI: 10.1136/bjophthalmol-2016-309160] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Revised: 07/18/2016] [Accepted: 08/28/2016] [Indexed: 11/03/2022]
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Ocular surface temperature in age-related macular degeneration. J Ophthalmol 2014; 2014:281010. [PMID: 25436140 PMCID: PMC4244689 DOI: 10.1155/2014/281010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 09/10/2014] [Indexed: 11/11/2022] Open
Abstract
Background. The aim of this study is to investigate the ocular thermographic profiles in age-related macular degeneration (AMD) eyes and age-matched controls to detect possible hemodynamic abnormalities, which could be involved in the pathogenesis of the disease. Methods. 32 eyes with early AMD, 37 eyes with atrophic AMD, 30 eyes affected by untreated neovascular AMD, and 43 eyes with fibrotic AMD were included. The control group consisted of 44 healthy eyes. Exclusion criteria were represented by any other ocular diseases other than AMD, tear film abnormalities, systemic cardiovascular abnormalities, diabetes mellitus, and a body temperature higher than 37.5°C. A total of 186 eyes without pupil dilation were investigated by infrared thermography (FLIR A320). The ocular surface temperature (OST) of three ocular points was calculated by means of an image processing technique from the infrared images. Two-sample t-test and one-way analysis of variance (ANOVA) test were used for statistical analyses. Results. ANOVA analyses showed no significant differences among AMD groups (P value >0.272). OST in AMD patients was significantly lower than in controls (P > 0.05). Conclusions. Considering the possible relationship between ocular blood flow and OST, these findings might support the central role of ischemia in the pathogenesis of AMD.
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Abstract
PURPOSE To determine the prevalence of retinal vascular abnormalities (RVA) in neovascular age-related macular degeneration (AMD). METHODS A post hoc subanalysis of images acquired during a Phase III randomized controlled trial was undertaken, selecting images from participants with untreated, neovascular AMD in at least one eye. Protocol mandated fundus photographs and fluorescein angiograms were acquired at baseline and Year 2, from 107 sham-treated study eyes with neovascular AMD and 107 untreated fellow eyes. Images were reanalyzed by an independent reading center for the presence of RVA, defined as at least one of the following: microaneurysms, vessel staining or leakage, dilated or tortuous vessels, intraretinal hemorrhage, vessel sheathing or narrowing, capillary nonperfusion, or capillary infarcts. RESULTS The baseline prevalence of RVA in the sham-treated study eyes was 14.4% (15 of 104 gradable images) versus 8.3% (5 of 60) in the fellow eyes with dry AMD. The baseline prevalence of individual RVAs in study eyes was: microaneurysms (6.7%), vessel staining or leakage (6.7%), dilated or tortuous vessels (4.8%), intraretinal hemorrhage (4.8%), vessel sheathing or narrowing (2.9%), capillary nonperfusion (0%), and capillary infarcts (0%). Results were similar at 24 months. CONCLUSION Compared with several studies that relied solely on fundus photographs, this study included fluorescein angiography and found a higher prevalence of RVAs occurring in eyes with neovascular AMD.
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Told R, Palkovits S, Boltz A, Schmidl D, Napora KJ, Werkmeister RM, Haslacher H, Frantal S, Popa‐Cherecheanu A, Schmetterer L, Garhöfer G. Flicker-induced retinal vasodilatation is not dependent on complement factor H polymorphism in healthy young subjects. Acta Ophthalmol 2014; 92:e540-5. [PMID: 24863099 PMCID: PMC4225479 DOI: 10.1111/aos.12433] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Accepted: 03/17/2014] [Indexed: 02/02/2023]
Abstract
Purpose The complement factor H (CFH) tyrosine 402 histidine (Y402H, rs1061170) variant is known to be significantly associated with age-related macular degeneration (AMD). Whether this genetic variant may impact retinal blood flow regulation is largely unknown. This study investigated whether flicker-induced vasodilation, an indicator for the coupling between neural activity and blood flow, is altered in subjects carrying the rs1061170 risk allele. Methods One hundred healthy subjects (aged between 18 and 45 years) were included in this study. Retinal blood flow regulation was tested by assessing retinal vessel calibres in response to stimulation with diffuse flicker light. Retinal vascular flicker responses were determined with a Dynamic Vessel Analyzer (DVA). In addition, genotyping for rs1061170 was performed. Results Eighteen subjects were homozygous for the risk allele C, 50 were homozygous for the ancestral allele T, and 31 subjects were heterozygous (CT). One subject had to be excluded from data evaluation, as no genetic analysis could be performed due to technical difficulties. Baseline diameters of retinal arteries (p = 0.39) and veins (p = 0.64) were comparable between the three groups. Flicker-induced vasodilation in both retinal arteries (p = 0.38) and retinal veins (p = 0.62) was also comparable between the three studied groups. Conclusions Our data indicate that homozygous healthy young carriers of the C risk allele at rs1061170 do not show abnormal flicker-induced vasodilation in the retina. This suggests that the high-risk genetic variant of CFH polymorphism does not impact neuro-vascular coupling in healthy subjects.
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Affiliation(s)
- Reinhard Told
- Department of Clinical Pharmacology Medical University of Vienna Vienna Austria
- Center for Medical Physics and Biomedical Engineering Medical University of Vienna Vienna Austria
| | - Stefan Palkovits
- Department of Clinical Pharmacology Medical University of Vienna Vienna Austria
| | - Agnes Boltz
- Department of Clinical Pharmacology Medical University of Vienna Vienna Austria
- Center for Medical Physics and Biomedical Engineering Medical University of Vienna Vienna Austria
| | - Doreen Schmidl
- Department of Clinical Pharmacology Medical University of Vienna Vienna Austria
| | - Katarzyna J. Napora
- Department of Clinical Pharmacology Medical University of Vienna Vienna Austria
- Center for Medical Physics and Biomedical Engineering Medical University of Vienna Vienna Austria
| | - René M. Werkmeister
- Center for Medical Physics and Biomedical Engineering Medical University of Vienna Vienna Austria
| | - Helmuth Haslacher
- Department of Laboratory Medicine Medical University of Vienna Vienna Austria
| | - Sophie Frantal
- Center for Medical Statistics Informatics and Intelligence Systems Medical University of Vienna Vienna Austria
| | | | - Leopold Schmetterer
- Department of Clinical Pharmacology Medical University of Vienna Vienna Austria
- Center for Medical Physics and Biomedical Engineering Medical University of Vienna Vienna Austria
| | - Gerhard Garhöfer
- Department of Clinical Pharmacology Medical University of Vienna Vienna Austria
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A combined method to quantify the retinal metabolic rate of oxygen using photoacoustic ophthalmoscopy and optical coherence tomography. Sci Rep 2014; 4:6525. [PMID: 25283870 PMCID: PMC4185377 DOI: 10.1038/srep06525] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 09/15/2014] [Indexed: 11/25/2022] Open
Abstract
Quantitatively determining physiological parameters at a microscopic level in the retina furthers the understanding of the molecular pathways of blinding diseases, such as diabetic retinopathy and glaucoma. An essential parameter, which has yet to be quantified noninvasively, is the retinal oxygen metabolic rate (rMRO2). Quantifying rMRO2 is challenging because two parameters, the blood flow rate and hemoglobin oxygen saturation (sO2), must be measured together. We combined photoacoustic ophthalmoscopy (PAOM) with spectral domain-optical coherence tomography (SD-OCT) to tackle this challenge, in which PAOM measured the sO2 and SD-OCT mapped the blood flow rate. We tested the integrated system on normal wild-type rats, in which the measured rMRO2 was 297.86 ± 70.23 nl/minute. This quantitative method may shed new light on both fundamental research and clinical care in ophthalmology in the future.
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Delayed patchy choroidal filling in the Comparison of Age-Related Macular Degeneration Treatments Trials (CATT). Am J Ophthalmol 2014; 158:525-31.e2. [PMID: 24949820 DOI: 10.1016/j.ajo.2014.06.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Revised: 06/11/2014] [Accepted: 06/11/2014] [Indexed: 11/20/2022]
Abstract
PURPOSE To determine the relationship between delayed patchy choroidal filling and morphologic and functional outcomes among eyes treated with ranibizumab or bevacizumab. DESIGN Cohort study. METHODS Comparison of Age-related Macular Degeneration Treatment Trials participants were assigned randomly to ranibizumab or bevacizumab on a monthly or as-needed schedule. Presence of delayed patchy choroidal filling and morphologic and functional outcomes were evaluated among eyes with gradable fluorescein angiography at baseline (n = 973) and at 1 year (n = 860) eyes. RESULTS Delayed filling was present in 75 (7.7%) of 973 eyes at baseline. Eyes with incident delayed filling at 1 year (23 [2.9%] of 798) showed a mean decrease of 1.7 letters in visual acuity, whereas eyes without incident delayed filling had a mean improvement of 8.1 letters (difference [Δ], -9.8; 95% confidence interval [CI] , -15.8 to -3.9; P < .01). Eyes with incident delayed filling had a larger increase in mean total lesion area of choroidal neovascularization (3.00 mm(2)) than eyes without incident delayed filling (0.56 mm(2); Δ , 2.4; 95% CI, 0.4 to 4.4; P = .02). The proportion with incident delayed filling at 1 year was similar among eyes treated with ranibizumab (10 [2.4%] of 413) or bevacizumab (13 [3.3%] of 385; P = .53) and among eyes treated monthly (12 [3.1%] of 388) or as needed (11 [2.7%] of 410; P = .83). CONCLUSIONS Delayed patchy choroidal filling was uncommon at baseline. Although only a small percentage of eyes demonstrated delayed filling during the first year of anti-vascular endothelial growth factor treatment, these eyes had worse visual acuity and a larger increase in total lesion area of choroidal neovascularization.
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McKeague C, Margrain TH, Bailey C, Binns AM. Low-level night-time light therapy for age-related macular degeneration (ALight): study protocol for a randomized controlled trial. Trials 2014; 15:246. [PMID: 24965385 PMCID: PMC4227140 DOI: 10.1186/1745-6215-15-246] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Accepted: 05/23/2014] [Indexed: 12/11/2022] Open
Abstract
Background Age-related macular degeneration (AMD) is the leading cause of blindness among older adults in the developed world. The only treatments currently available, such as ranibizumab injections, are for neovascular AMD, which accounts for only 10 to 15% of people with the condition. Hypoxia has been implicated as one of the primary causes of AMD, and is most acute at night when the retina is most metabolically active. By increasing light levels at night, the metabolic requirements of the retina and hence the hypoxia will be considerably reduced. This trial seeks to determine whether wearing a light mask that emits a dim, green light during the night can prevent the progression of early AMD. Methods/design ALight is a Phase I/IIa, multicentre, randomized controlled trial. Sixty participants (55 to 88 years old) with early AMD in one eye and neovascular AMD (nAMD) in the fellow eye will be recruited from nAMD clinics. They will be randomized (in the ratio 1:1), either to receive the intervention or to be in the untreated control group, stratified according to risk of disease progression. An additional 40 participants with healthy retinal appearance, or early AMD only, will be recruited for a baseline cross-sectional analysis. The intervention is an eye mask that emits a dim green light to illuminate the retina through closed eyelids at night. This is designed to reduce the metabolic activity of the retina, thereby reducing the potential risk of hypoxia. Participants will wear the mask every night for 12 months. Ophthalmologists carrying out monthly assessments will be masked to the treatment group, but participants will be aware of their treatment group. The primary outcome measure is the proportion of people who show disease progression during the trial period in the eye with early AMD. A co-primary outcome measure is the rate of retinal adaptation. As this is a trial of a CE-marked device for an off-label indication, a further main aim of this trial is to assess safety of the mask in the cohort of participants with AMD. Trial registration International Standard Randomised Controlled Trials Register: ISRCTN82148651
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Affiliation(s)
| | | | | | - Alison M Binns
- School of Optometry and Vision Sciences, Cardiff University, Cardiff CF24 4 LU, UK.
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Retinal and Choroidal Thickness Changes after Single Anti-VEGF Injection in Neovascular Age-related Macular Degeneration: Ranibizumab vs Bevacizumab. Eur J Ophthalmol 2014; 24:904-10. [DOI: 10.5301/ejo.5000478] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/03/2014] [Indexed: 01/07/2023]
Abstract
Purpose To evaluate and compare the effects of single intravitreal injection of ranibizumab and bevacizumab on central retinal and choroidal thickness in patients with neovascular age-related macular degeneration (AMD). Methods Forty eyes of 40 patients with neovascular AMD that underwent intravitreal injection of vascular endothelial growth factor inhibitors (anti-VEGFs) were included. Patients were randomized into 2 groups: 20 eyes received ranibizumab and 20 eyes received bevacizumab injection. Central retinal and choroidal thicknesses of all eyes at baseline and 1 month postinjection scans were measured with Fourier-domain optical coherence tomography (OCT). Student t test and Mann-Whitney U test were used to compare the data. Results The mean central retinal thickness (CRT) showed significant decrease after single injection of ranibizumab (from 345.0 μm to 253.5 μm, p<0.01) and bevacizumab (from 329.5 μm to 251.0 μm, p<0.01) at the first month, respectively. There was no significant difference regarding the CRT change between groups (p = 0.39). The mean choroidal thickness decreased from 158.6 μm (115-317) to 155.5 μm (111-322) in the ranibizumab group and from 211.5 μm (143-284) to 201.5 μm (93-338) in bevacizumab group. The decrease was not significant between groups (p = 0.35). Conclusions Intravitreal injection of both ranibizumab and bevacizumab provided a significant decrease in CRT; however, the agents caused no significant change in choroidal thickness. Additionally, no difference between ranibizumab versus bevacizumab was observed related to macular edema inhibition.
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Boddu S, Lee MD, Marsiglia M, Marmor M, Freund KB, Smith RT. Risk factors associated with reticular pseudodrusen versus large soft drusen. Am J Ophthalmol 2014; 157:985-993.e2. [PMID: 24491417 DOI: 10.1016/j.ajo.2014.01.023] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 01/22/2014] [Accepted: 01/23/2014] [Indexed: 10/25/2022]
Abstract
PURPOSE To investigate genetic, environmental, and systemic risk factors in prospectively identified subjects with the age-related macular degeneration (AMD) phenotypes of (1) reticular pseudodrusen without large soft drusen and (2) large soft drusen without reticular pseudodrusen. DESIGN Prospective case-case comparison. METHODS In a clinical practice setting, patients with AMD were sequentially screened using clinical examination and scanning laser ophthalmoscopy imaging to prospectively identify subjects (n = 73) with the phenotypes of (1) reticular pseudodrusen without large soft drusen (n = 30) or (2) large soft drusen without reticular pseudodrusen (n = 43). Subjects were genotyped for 2 alleles associated with AMD, age-related maculopathy susceptibility 2 (ARMS2) and complement factor H (CFH). A questionnaire was administered to collect history of smoking, hypertension, diabetes, and hyperlipidemia, as well as personal and family history of AMD. RESULTS The reticular pseudodrusen group was older (median age 87 vs 81 years, P = .04) and had more female subjects (83.3% vs 48.8%, P = .003), later ages of AMD onset (83 vs 70 years, P = .0005), and a greater frequency of hypertension (76.7% vs 55.8%, P = .08). No significant differences were found in the distribution of the ARMS2 risk allele (P = .4) between the reticular pseudodrusen (homozygous = 20.0%; heterozygous = 56.7%) and large soft drusen (homozygous = 19.0%; heterozygous = 42.9%) phenotypes, or in the distribution of the CHF risk allele (P = .7) between the reticular pseudodrusen (homozygous = 26.7%; heterozygous = 56.7%) and large soft drusen (homozygous = 21.4%; heterozygous = 66.7%) phenotypes. CONCLUSIONS The reticular pseudodrusen phenotype was associated with increased age, later age of AMD onset, and female sex.
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Wickremasinghe SS, Chong EWT, Guymer RH. Lifestyle and age-related macular degeneration. EXPERT REVIEW OF OPHTHALMOLOGY 2014. [DOI: 10.1586/17469899.4.1.79] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Functional hyperemia and mechanisms of neurovascular coupling in the retinal vasculature. J Cereb Blood Flow Metab 2013; 33:1685-95. [PMID: 23963372 PMCID: PMC3824187 DOI: 10.1038/jcbfm.2013.145] [Citation(s) in RCA: 159] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Revised: 07/19/2013] [Accepted: 07/22/2013] [Indexed: 11/08/2022]
Abstract
The retinal vasculature supplies cells of the inner and middle layers of the retina with oxygen and nutrients. Photic stimulation dilates retinal arterioles producing blood flow increases, a response termed functional hyperemia. Despite recent advances, the neurovascular coupling mechanisms mediating the functional hyperemia response in the retina remain unclear. In this review, the retinal functional hyperemia response is described, and the cellular mechanisms that may mediate the response are assessed. These neurovascular coupling mechanisms include neuronal stimulation of glial cells, leading to the release of vasoactive arachidonic acid metabolites onto blood vessels, release of potassium from glial cells onto vessels, and production and release of nitric oxide (NO), lactate, and adenosine from neurons and glia. The modulation of neurovascular coupling by oxygen and NO are described, and changes in functional hyperemia that occur with aging and in diabetic retinopathy, glaucoma, and other pathologies, are reviewed. Finally, outstanding questions concerning retinal blood flow in health and disease are discussed.
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Burgansky-Eliash Z, Barash H, Nelson D, Grinvald A, Sorkin A, Loewenstein A, Barak A. Retinal Blood Flow Velocity in Patients with Age-Related Macular Degeneration. Curr Eye Res 2013; 39:304-11. [DOI: 10.3109/02713683.2013.840384] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Sakalar YB, Senturk S, Yildirim M, Keklikci U, Alakus MF, Unlu K. Evaluation of retrobulbar blood flow by color doppler ultrasonography after intravitreal ranibizumab injection in patients with neovascular age-related macular degeneration. JOURNAL OF CLINICAL ULTRASOUND : JCU 2013; 41:32-37. [PMID: 23055187 DOI: 10.1002/jcu.21989] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Accepted: 08/13/2012] [Indexed: 06/01/2023]
Abstract
PURPOSE This study aimed to evaluate the changes in retrobulbar blood flow by using color Doppler sonography in patients who had undergone intravitreal ranibizumab injection for neovascular age-related macular degeneration (AMD). METHODS The study comprised 37 AMD patients who had undergone intravitreal 0.5 mg ranibizumab injection. The ophthalmic artery, central retinal artery, and short lateral posterior ciliary artery of both eyes of patients were evaluated by color Doppler sonography. Peak systolic velocity, end-diastolic velocity, and resistance index were calculated before injection, and after injection on day 7 and day 30. The pre- and postinjection values were compared using Wilcoxon signed rank test. RESULTS In a comparison with the preinjection values of peak systolic velocity, end-diastolic velocity, and resistance index, the postinjection values at both day 7 and day 30 showed no statistically significant difference in ophthalmic artery, lateral posterior ciliary artery, and central retinal artery (p > 0.05). Similarly, for the same parameters, pre- and postinjection values in the uninjected fellow eye showed no statistically significant difference (P > 0.05). CONCLUSIONS Intravitreal ranibizumab injection for neovascular AMD does not cause a significant change in the retrobulbar blood flow in either the injected eye or the fellow eye.
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Machalińska A, Kawa MP, Marlicz W, Machaliński B. Complement system activation and endothelial dysfunction in patients with age-related macular degeneration (AMD): possible relationship between AMD and atherosclerosis. Acta Ophthalmol 2012; 90:695-703. [PMID: 22067048 DOI: 10.1111/j.1755-3768.2011.02295.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Age-related macular degeneration (AMD) shares several pathological and epidemiological similarities with systemic atherosclerosis (AS). First, an association between AS and AMD is apparent from the analyses of the histological and biochemical structure of atherosclerotic plaques in the vascular walls and retinal drusen, the hallmark of AMD. Second, there is considerable evidence implicating endothelial dysfunction in the pathogenesis of both disorders, and cellular oxidative stress appears to be a common denominator underlying this process. Moreover, there are observations that the complement system (CS) triggering inflammatory response contributes to the onset and advancement of both diseases. The CS plays a role in the generation of drusen and neovascularization in AMD as well as in vascular endothelium activation, cell damage and ultimately atherosclerotic plaque formation in the course of systemic arteriosclerosis. It is widely recognized that both AMD and AS are not only related to local stimulation of the CS, but also result in its systemic activation. In addition, a specific Y402H polymorphism of the complement inhibitor factor H has been found to be associated with the incidence of both AMD and AS. Here, we propose a linking hypothesis between CS activation, endothelial dysfunction and the pathogenesis of two common and age-related pathological processes, AS and AMD. We also discuss the potential therapeutic value of pharmacological modulation of CS activation in these disorders.
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Affiliation(s)
- Anna Machalińska
- Department of Ophthalmology, Pomeranian Medical University, Szczecin, Poland
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Wickremasinghe SS, Xie J, Guymer RH, Wong TY, Kawasaki R, Qureshi S. Retinal vascular changes following intravitreal ranibizumab injections for neovascular AMD over a 1-year period. Eye (Lond) 2012; 26:958-66. [PMID: 22562186 PMCID: PMC3396172 DOI: 10.1038/eye.2012.72] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Accepted: 03/13/2012] [Indexed: 11/10/2022] Open
Abstract
PURPOSE To assess retinal vascular calibre changes in eyes with neovascular age-related macular degeneration (AMD), treated with intravitreal anti-vascular endothelial growth factor agents, over a 1-year period and compare any such changes to untreated fellow eyes. METHODS Treatment naïve patients with neovascular AMD received three consecutive intravitreal injections of ranibizumab, followed by a pro re nata dosing regimen up to 1 year, with the aim of maintaining a 'fluid-free' macula. Retinal arteriolar and venular calibre was measured from digital fundus photographs at baseline and at three monthly intervals to 1 year, and summarised as central retinal artery equivalent (CRAE) and central retinal venular equivalent (CRVE), respectively. RESULTS A total of 53 injected eyes and 41 fellow, non-injected eyes were analysed. At baseline, there were no differences in retinal vascular calibre between injected and non-injected eyes (mean CRAE (SD) 144.93 (14.07) vs 145.74 (13.10) μm, P=0.80 and mean CRVE (SD) 216.23 (25.93) vs 219.91 (22.82) μm, P=0.53). Over a 12-month period, retinal venular calibre dilatation occurred in injected eyes (mean CRVE change +5.71 (14.71) μm, P=0.007), with no change in retinal arterioles, +0.69 (14.71) μm, P=0.68. In non-injected eyes, arteriolar narrowing occurred as a whole, mean CRAE change -4.20 (7.00) μm, P=0.001, over 12 months, with a trend for narrowing in venules, -2.16 (11.56) μm, P=0.28. In injected eyes, after controlling for covariates, the changes in CRVE over 12 months mirrored improvements in macular thickness, -0.06 (-0.005, -0.11) μm, P=0.04, and visual acuity, +9.66 (-0.30, +19.32) μm, P=0.06. CONCLUSION Intravitreal ranibizumab significantly dilated retinal venules after a 1-year period.
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Affiliation(s)
- S S Wickremasinghe
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
| | - J Xie
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
| | - R H Guymer
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
| | - T Y Wong
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
- Singapore Eye Research Institute, National University of Singapore, Singapore, Singapore
| | - R Kawasaki
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
| | - S Qureshi
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
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Kur J, Newman EA, Chan-Ling T. Cellular and physiological mechanisms underlying blood flow regulation in the retina and choroid in health and disease. Prog Retin Eye Res 2012; 31:377-406. [PMID: 22580107 DOI: 10.1016/j.preteyeres.2012.04.004] [Citation(s) in RCA: 434] [Impact Index Per Article: 36.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Revised: 04/17/2012] [Accepted: 04/22/2012] [Indexed: 02/06/2023]
Abstract
We review the cellular and physiological mechanisms responsible for the regulation of blood flow in the retina and choroid in health and disease. Due to the intrinsic light sensitivity of the retina and the direct visual accessibility of fundus blood vessels, the eye offers unique opportunities for the non-invasive investigation of mechanisms of blood flow regulation. The ability of the retinal vasculature to regulate its blood flow is contrasted with the far more restricted ability of the choroidal circulation to regulate its blood flow by virtue of the absence of glial cells, the markedly reduced pericyte ensheathment of the choroidal vasculature, and the lack of intermediate filaments in choroidal pericytes. We review the cellular and molecular components of the neurovascular unit in the retina and choroid, techniques for monitoring retinal and choroidal blood flow, responses of the retinal and choroidal circulation to light stimulation, the role of capillaries, astrocytes and pericytes in regulating blood flow, putative signaling mechanisms mediating neurovascular coupling in the retina, and changes that occur in the retinal and choroidal circulation during diabetic retinopathy, age-related macular degeneration, glaucoma, and Alzheimer's disease. We close by discussing issues that remain to be explored.
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Affiliation(s)
- Joanna Kur
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA
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Jaillon F, Makita S, Yasuno Y. Variable velocity range imaging of the choroid with dual-beam optical coherence angiography. OPTICS EXPRESS 2012; 20:385-96. [PMID: 22274362 DOI: 10.1364/oe.20.000385] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
In this study, we present dual-beam Doppler optical coherence angiography with variable beam separation. Altering beam distance, independently of the scanning protocol, provides a flexible way to select the velocity range of detectable blood flow. This system utilized a one-micrometer wavelength light source to visualize deep into the posterior eye, i.e., the choroid. Two-dimensional choroidal vasculature maps of a human subject acquired with different beam separations, and hence with several velocity ranges, are presented. Combining these maps yields a semi-quantitative visualization of axial velocity of the choroidal circulation. The proposed technique may be useful for identifying choroidal abnormalities that occur in pathological conditions of the eye.
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Affiliation(s)
- Franck Jaillon
- Computational Optics Group, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan
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Wood A, Binns A, Margrain T, Drexler W, Považay B, Esmaeelpour M, Sheen N. Retinal and choroidal thickness in early age-related macular degeneration. Am J Ophthalmol 2011; 152:1030-1038.e2. [PMID: 21851922 DOI: 10.1016/j.ajo.2011.05.021] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Revised: 05/12/2011] [Accepted: 05/18/2011] [Indexed: 01/21/2023]
Abstract
PURPOSE To compare retinal thickness and choroidal thickness at increasing retinal eccentricity in individuals with early age-related macular degeneration (AMD) and in healthy controls using enhanced choroidal penetration, 3-dimensional optical coherence tomography at 1060 nm. DESIGN Cross-sectional study. METHODS Individuals with early AMD (n = 16; mean age, 71.6 ± 8.5 years) and a comparison group of healthy controls (n = 16; 67.6 ± 5.4 years) were recruited. Three-dimensional (20 degrees × 20 degrees) long-wavelength optical coherence tomography (1060 nm) images (approximately 8-μm axial resolution; 47,000 A scans/second, centered on the fovea) were obtained from all participants after pupil dilation. Retinal thickness was measured between the inner limiting membrane and the retinal pigment epithelium. Choroidal thickness was measured between the retinal pigment epithelium and the choroid-scleral interface. Thickness measurements were obtained subfoveally and at 0.5-mm intervals to a maximum of 2.0 mm nasally, temporally, superiorly, and inferiorly. The main outcome measures were retinal and choroidal thickness (measured in micrometers) at different eccentricities on vertical and horizontal meridians. RESULTS Mean retinal thickness was reduced significantly in the group of participants with early AMD compared with the control group at multiple locations within 2.0 mm of the fovea. This difference was most significant at the fovea, where the mean retinal thickness of the early AMD group was 179 ± 27 μm and that of the control group was 202 ± 18 μm (P = .008). There was no significant difference in choroidal thickness between groups at any location. CONCLUSIONS Retinal thickness is reduced in early AMD, but choroidal thickness seems to be unaffected by the early disease process.
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Affiliation(s)
- Ashley Wood
- School of Optometry and Vision Sciences, Cardiff University, United Kingdom
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Caprara C, Grimm C. From oxygen to erythropoietin: relevance of hypoxia for retinal development, health and disease. Prog Retin Eye Res 2011; 31:89-119. [PMID: 22108059 DOI: 10.1016/j.preteyeres.2011.11.003] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Revised: 11/01/2011] [Accepted: 11/07/2011] [Indexed: 12/20/2022]
Abstract
Photoreceptors and other cells of the retina consume large quantities of energy to efficiently convert light information into a neuronal signal understandable by the brain. The necessary energy is mainly provided by the oxygen-dependent generation of ATP in the numerous mitochondria of retinal cells. To secure the availability of sufficient oxygen for this process, the retina requires constant blood flow through the vasculature of the retina and the choroid. Inefficient supply of oxygen and nutrients, as it may occur in conditions of disturbed hemodynamics or vascular defects, results in tissue ischemia or hypoxia. This has profound consequences on retinal function and cell survival, requiring an adaptational response by cells to cope with the reduced oxygen tension. Central to this response are hypoxia inducible factors, transcription factors that accumulate under hypoxic conditions and drive the expression of a large variety of target genes involved in angiogenesis, cell survival and metabolism. Prominent among these factors are vascular endothelial growth factor and erythropoietin, which may contribute to normal angiogenesis during development, but may also cause neovascularization and vascular leakage under pathologically reduced oxygen levels. Since ischemia and hypoxia may have a role in various retinal diseases such as diabetic retinopathy and retinopathy of prematurity, studying the cellular and molecular response to reduced tissue oxygenation is of high relevance. In addition, the concept of preconditioning with ischemia or hypoxia demonstrates the capacity of the retina to activate endogenous survival mechanisms, which may protect cells against a following noxious insult. Part of these mechanisms is the local production of protective factors such as erythropoietin. Due to its plethora of effects in the retina including neuro- and vaso-protective activities, erythropoietin has gained strong interest as potential therapeutic factor for retinal degenerative diseases.
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Affiliation(s)
- Christian Caprara
- Lab for Retinal Cell Biology, Department of Ophthalmology, University of Zurich, Zurich, Switzerland
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Lanzl IM, Seidova SF, Maier M, Lohmann C, Schmidt-Trucksäss A, Halle M, Kotliar KE. Dynamic retinal vessel response to flicker in age-related macular degeneration patients before and after vascular endothelial growth factor inhibitor injection. Acta Ophthalmol 2011; 89:472-9. [PMID: 20102347 DOI: 10.1111/j.1755-3768.2009.01718.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE Retinal vessel responses to flickering light are different in various systemic and ocular diseases and can be improved after successful therapy. We investigated retinal vessel response to flickering light in age-related macular degeneration (AMD) patients before and after treatment with a single intravitreal bevacizumab (Avastin(®) ) injection. METHODS In 10 patients with exudative AMD [age: median (1.quartile; 3.quartile) 76.0 (73.5; 80.0) years], retinal vessel reactions were examined by Dynamic Vessel Analyser (DVA) before and 3 months after a single intravitreal application of bevacizumab (1.25 mg). A baseline measurement was followed by three consecutive monochromatic flicker stimulations (530-600 nm, 12.5 Hz, 20 seconds). Temporal retinal vessel reaction was analysed and compared with the reaction in healthy controls. RESULTS Mean arterial dilation at the end of flicker was not different in all groups. For veins this parameter amounted to: pre-treatment, 2.6 (1.7; 3.9)%; post-treatment, 2.9 (2.4; 4.0)%; control, 4.3 (3.2; 5.7)%; significant: pre-treatment - control (Dunnett's procedure, p < 0.05). Maximal dilation occurred in arteries at: pre-treatment, 17.5 (14.8; 32.5) seconds; post-treatment, 18.0 (16.6; 30.6) seconds; control, 14.5 (10.8; 17.3) seconds. Both AMD groups were slower (p < 0.05): in veins at 17.0 (14.5; 20.0) seconds, 12.8 (8.6; 14.8) seconds and 18.5 (17.1; 19.9) seconds, respectively; significant post-treatment - control (p < 0.05). In the post-treatment AMD group arterial constriction after stimulation occurred more slowly compared with the control group (p < 0.05). CONCLUSION Dynamic retinal arterial and venous reactions to flickering light are altered in AMD compared with controls. Three months after a single injection of a vascular endothelial growth factor inhibitor, the investigated retinal dynamic vascular parameters were not altered in our study.
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Affiliation(s)
- Ines M Lanzl
- Department of Ophthalmology, Munich University of Technology, Munich, Germany
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Rechtman E, Stalmans I, Glovinsky J, Breusegem C, Moisseiev J, Van Calster J, Harris A. The effect of intravitreal bevacizumab (Avastin) on ocular pulse amplitude in neovascular age-related macular degeneration. Clin Ophthalmol 2011; 5:37-44. [PMID: 21386919 PMCID: PMC3048056 DOI: 10.2147/opth.s15810] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
PURPOSE To evaluate the effect of intravitreal (IVT) bevacizumab in neovascular age-related macular degeneration (AMD) on global choroidal hemodynamics, as measured by ocular pulse amplitude (OPA). METHODS This was a two-center prospective study (Sheba Medical Center, Israel, and University Hospitals Leuven, Belgium). AMD patients who required IVT bevacizumab (1.25 mg/0.05 mL; first or repeated) were examined three times: at days 0 (prior to injection), 7 (±3), and 28 (±7) postinjection. At each visit, OPAs of both eyes were measured using the Pascal dynamic contour tonometer (DCT). A paired t-test between preoperative and postoperative OPA was conducted. Pearson correlation was used to evaluate the influence of various measured parameters on DCT-OPA. RESULTS A total of 38 neovascular AMD patients were recruited, and 30 patients were included in the final analysis (18 females and 12 males; age 78.8 ± 5.82 years [mean ± standard deviation]). A good correlation was found throughout the study between the DCT-intraocular pressure (IOP) and Goldmann IOP and between DCT-IOP and DCT-OPA. No change in OPA of bevacizumab-treated eyes was found between the visits (2.24 ± 0.73, 2.2 ± 0.86, and 2.23 ± 0.73 mm Hg at visits 1, 2, and 3, respectively; paired t-test: P = 0.77 between visits 1 and 2, P = 0.98 between visits 1 and 3). No correlations were found between DCT-OPA and age, heart rate, systemic blood pressure, axial length, keratometry readings, and central corneal thickness. CONCLUSIONS OPA, an indirect measure of global choroidal hemodynamics, remains unchanged following IVT off-label bevacizumab. This finding adds to the growing evidence regarding the safety profile of bevacizumab in AMD treatment.
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Affiliation(s)
- Ehud Rechtman
- Goldschleger Eye Institute, Sheba Medical Center, Ramat Gan, Israel
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Çekiç O, Bardak Y, Yeşildağ A. Color Doppler Imaging of Ocular Blood Flow after Combined Photodynamic Therapy with Intravitreal Triamcinolone in Age-Related Macular Degeneration. Curr Eye Res 2010; 36:149-53. [DOI: 10.3109/02713683.2010.533809] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Abstract
Ischemia and hypoxia have been implicated in the pathophysiology of age related macular degeneration (AMD). This has mostly been based on studies on choroidal perfusion, which is not the only contributor to retinal hypoxia found in AMD eyes. Other features of AMD may also interfere with retinal oxygen metabolism including confluent drusen, serous or hemorrhagic retinal detachment, retinal edema and vitreoretinal adhesion. Each of these features contributes to retinal hypoxia: the drusen and retinal elevation by increasing the distance between the choriocapillaris and retina; vitreoretinal adhesion by reducing diffusion and convection of oxygen towards and vascular endothelial growth factor (VEGF) away from hypoxic retinal areas. Hypoxia-inducible-factor is known to exist in subretinal neovascularization and hypoxia is the main stimulus for the production of VEGF. Each feature may not by itself create enough hypoxia and VEGF accumulation to stimulate wet AMD, but they may combine to do so. Choroidal ischemia in AMD has been demonstrated by many researchers, using different technologies. Choroidal ischemia obviously decreases oxygen delivery to the outer retina. Confluent drusen, thickening of Bruch's membrane and any detachment of retina or retinal pigment epithelium, increases the distance between the choriocapillaris and the retina and thereby reduces the oxygen flux from the choroid to the outer retina according to Fick's law of diffusion. Retinal elevation and choroidal ischemia may combine forces to reduce choroidal oxygen delivery to the outer retina, produce retinal hypoxia. Hypoxia leads to production of VEGF leading to neovascularization and tissue edema. A vicious cycle may develop, where VEGF production increases effusion, retinal detachment and edema, further increasing hypoxia and VEGF production. Adhesion of the viscous posterior vitreous cortex to the retina maintains a barrier to diffusion and convection currents in the vitreous cavity according to the laws of Fick's, Stokes-Einstein and Hagen-Poiseuille. If the vitreous is detached from the surface of the retina, the low viscosity fluid transports oxygen and nutrients towards an ischemic area of the retina, and cytokines away from the retina, at a faster rate than through attached vitreous gel. Vitreoretinal adhesion can exacerbate retinal hypoxia and accumulation of cytokines, such as VEGF. Vitreoretinal traction can also cause hypoxia by retinal elevation. Conceivably, the basic features of AMD, drusen, choroidal ischemia, and vitreoretinal adhesion are independently determined by genetics and environment and may combine in variable proportions. If the resulting hypoxia and consequent VEGF accumulation crosses a threshold, this will trigger effusion and neovascularization.
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Affiliation(s)
- Einar Stefánsson
- University of Iceland, National University Hospital, 101 Reykjavík, Iceland.
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