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Cerquera-Jaramillo MA, Nava-Mesa MO, González-Reyes RE, Tellez-Conti C, de-la-Torre A. Visual Features in Alzheimer's Disease: From Basic Mechanisms to Clinical Overview. Neural Plast 2018; 2018:2941783. [PMID: 30405709 PMCID: PMC6204169 DOI: 10.1155/2018/2941783] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 08/07/2018] [Indexed: 12/16/2022] Open
Abstract
Alzheimer's disease (AD) is the leading cause of dementia worldwide. It compromises patients' daily activities owing to progressive cognitive deterioration, which has elevated direct and indirect costs. Although AD has several risk factors, aging is considered the most important. Unfortunately, clinical diagnosis is usually performed at an advanced disease stage when dementia is established, making implementation of successful therapeutic interventions difficult. Current biomarkers tend to be expensive, insufficient, or invasive, raising the need for novel, improved tools aimed at early disease detection. AD is characterized by brain atrophy due to neuronal and synaptic loss, extracellular amyloid plaques composed of amyloid-beta peptide (Aβ), and neurofibrillary tangles of hyperphosphorylated tau protein. The visual system and central nervous system share many functional components. Thus, it is plausible that damage induced by Aβ, tau, and neuroinflammation may be observed in visual components such as the retina, even at an early disease stage. This underscores the importance of implementing ophthalmological examinations, less invasive and expensive than other biomarkers, as useful measures to assess disease progression and severity in individuals with or at risk of AD. Here, we review functional and morphological changes of the retina and visual pathway in AD from pathophysiological and clinical perspectives.
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Affiliation(s)
| | - Mauricio O. Nava-Mesa
- Grupo de Investigación en Neurociencias (NeURos), Escuela de Medicina y Ciencias de la Salud, Universidad del Rosario, Bogotá, Colombia
| | - Rodrigo E. González-Reyes
- Grupo de Investigación en Neurociencias (NeURos), Escuela de Medicina y Ciencias de la Salud, Universidad del Rosario, Bogotá, Colombia
| | - Carlos Tellez-Conti
- Escuela Superior de Oftalmología-Instituto Barraquer de América, Bogotá, Colombia
| | - Alejandra de-la-Torre
- Grupo de Investigación en Neurociencias (NeURos), Escuela de Medicina y Ciencias de la Salud, Universidad del Rosario, Bogotá, Colombia
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Chan VTT, Sun Z, Tang S, Chen LJ, Wong A, Tham CC, Wong TY, Chen C, Ikram MK, Whitson HE, Lad EM, Mok VCT, Cheung CY. Spectral-Domain OCT Measurements in Alzheimer's Disease: A Systematic Review and Meta-analysis. Ophthalmology 2018; 126:497-510. [PMID: 30114417 DOI: 10.1016/j.ophtha.2018.08.009] [Citation(s) in RCA: 204] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2018] [Revised: 08/02/2018] [Accepted: 08/06/2018] [Indexed: 02/07/2023] Open
Abstract
TOPIC OCT is a noninvasive tool to measure specific retinal layers in the eye. The relationship of retinal spectral-domain (SD) OCT measurements with Alzheimer's disease (AD) and mild cognitive impairment (MCI) remains unclear. Hence, we conducted a systematic review and meta-analysis to examine the SD OCT measurements in AD and MCI. CLINICAL RELEVANCE Current methods of diagnosing early AD are expensive and invasive. Retinal measurements of SD OCT, which are noninvasive, technically simple, and inexpensive, are potential biomarkers of AD. METHODS We conducted a literature search in PubMed and Excerpta Medica Database to identify studies published before December 31, 2017, that assessed the associations between AD, MCI, and measurements of SD OCT: ganglion cell-inner plexiform layer (GC-IPL), ganglion cell complex (GCC), macular volume, and choroidal thickness, in addition to retinal nerve fiber layer (RNFL) and macular thickness. We used a random-effects model to examine these relationships. We also conducted meta-regression and assessed heterogeneity, publication bias, and study quality. RESULTS We identified 30 eligible studies, involving 1257 AD patients, 305 MCI patients, and 1460 controls, all of which were cross-sectional studies. In terms of the macular structure, AD patients showed significant differences in GC-IPL thickness (standardized mean difference [SMD], -0.46; 95% confidence interval [CI], -0.80 to -0.11; I2 = 71%), GCC thickness (SMD, -0.84; 95% CI, -1.10 to -0.57; I2 = 0%), macular volume (SMD, -0.58; 95% CI, -1.03 to -0.14; I2 = 80%), and macular thickness of all inner and outer sectors (SMD range, -0.52 to -0.74; all P < 0.001) when compared with controls. Peripapillary RNFL thickness (SMD, -0.67; 95% CI, -0.95 to -0.38; I2 = 89%) and choroidal thickness (SMD range, -0.88 to -1.03; all P < 0.001) also were thinner in AD patients. CONCLUSIONS Our results confirmed the associations between retinal measurements of SD OCT and AD, highlighting the potential usefulness of SD OCT measurements as biomarkers of AD.
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Affiliation(s)
- Victor T T Chan
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China; Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong, China
| | - Zihan Sun
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Shumin Tang
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Li Jia Chen
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Adrian Wong
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong, China
| | - Clement C Tham
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Tien Y Wong
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Republic of Singapore; Duke-NUS Medical School, National University of Singapore, Singapore, Republic of Singapore
| | - Christopher Chen
- Memory Aging and Cognition Centre, National University Health System, Singapore, Republic of Singapore; Department of Pharmacology, National University of Singapore, Singapore, Republic of Singapore
| | - M Kamran Ikram
- Departments of Neurology and Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Heather E Whitson
- Duke University Medical Center, Durham, North Carolina; Geriatrics Research Education and Clinical Center (GRECC), Durham VA Medical Center, Durham, North Carolina
| | | | - Vincent C T Mok
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong, China; Therese Pei Fong Chow Research Centre for Prevention of Dementia, The Chinese University of Hong Kong, Hong Kong, China
| | - Carol Y Cheung
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China.
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Dong Z, Luo A, Gan Y, Li J. Amyloid Beta Deposition Could Cause Corneal Epithelial Cell Degeneration Associated with Increasing Apoptosis in APPswePS1 Transgenic Mice. Curr Eye Res 2018; 43:1326-1333. [PMID: 30015526 DOI: 10.1080/02713683.2018.1501070] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
OBJECTIVE To investigate the expression of amyloid precursor protein (APP) and amyloid beta (Aβ) in cornea and further explore the pathological and ultrastructural changes in corneal epithelium in APPswePS1 transgenic mice. METHODS Twelve wild type mice were grouped into control group and twelve TgAPPswePS1 mice at least 8 months old were grouped into the young experiment group (Tg-8M group), and another twelve transgenic mice at least 15 months old were selected into the aged experiment group (Tg-15M group). The pathological degeneration, ultrastructural changes, and the expression of APP, Aβ deposition, and the TUNEL reaction in corneal epithelial cells were observed. Western blot analysis was performed to determine expression levels of APP and Aβ with scraped epithelial debridement. All the results were quantified and analyzed. RESULTS In transgenic mice, the H&E-stained cornea sections demonstrated histopathological changes in corneal epithelial cells with irregular arrangement and the number of cell layers decreased, while normal structure observed in controls. In Tg-15M group, the corneal epithelial cell displaced a significant number of intracellular vacuoles with 1-2 cell layers left. Transmission electron microscopy (TEM) further confirmed the dramatic degeneration in corneal epithelium, the microvilli suffered degenerative changes and found with typical fingerpoint-like morphology in controls; however, microspike-like in Tg-15M group, and the number of microvilli decreased considerabely. An APP-positive immunoreaction was detected with a diffuse pattern in the corneal epithelial cells layer, about 3.122 ± 0.596 and 7.372 ± 0.936 fold changes in Tg-8M and Tg-15M groups, respectively, as compared with controls. On corneal flatmount, Aβ deposition found a diffuse pattern in the cytoplasm by fluorescence staining in TgAPPswePS1 with significantly increasing as compared with the controls, but no plaque was found. The apoptosis of TUNEL cells were observed in TgAPPswePS1 mice and increased 16.329 ± 3.542 fold changes in Tg-15M group as compared with controls. CONCLUSION The APP expression and Aβ deposition might cause cornea epithelial cells degeneration in TgAPPswePS1 mice, associated with apoptosis in basal lamina cells.
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Affiliation(s)
- Zhizhang Dong
- a Department of Ophthalmology , The second Affiliated Hospital and Yuying Children' s Hospital of Wenzhou Medical University , Wenzhou , Zhejiang Province , China
| | - Ali Luo
- b Department of Pathology , the Chest Hospital of Xi 'an , Xi'an , Shaanxi Province , China
| | - Yifeng Gan
- c Physical Emergency Department , The second Affiliated Hospital and Yuying Children' s Hospital of Wenzhou Medical University , Wenzhou , Zhejiang Province , China
| | - Juan Li
- d Shaanxi Ophthalmic Medical Center, Xi'an No. 4 Hospital , Guangren Hospital Affiliated to School of Medicine of Xi'an Jiaotong University , Xi'an , Shaanxi Province , China
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Colligris P, Perez de Lara MJ, Colligris B, Pintor J. Ocular Manifestations of Alzheimer's and Other Neurodegenerative Diseases: The Prospect of the Eye as a Tool for the Early Diagnosis of Alzheimer's Disease. J Ophthalmol 2018; 2018:8538573. [PMID: 30151279 PMCID: PMC6091327 DOI: 10.1155/2018/8538573] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 06/07/2018] [Accepted: 06/26/2018] [Indexed: 12/20/2022] Open
Abstract
Dementia, including Alzheimer's disease (AD), is a major disorder, leading to several ocular manifestations amongst the elderly population. These visual disorders may be due to retinal nerve degenerative changes, including nerve fibre layer thinning, degeneration of retinal ganglion cells, and changes to vascular parameters. There is no cure for Alzheimer's, but medicines can slow down the development of many of the classic symptoms, such as loss of memory and communication skills, mood swings, and depression. The disease diagnosis is difficult, and it is only possible through PET scans of the brain, detecting evidence of the accumulation of amyloid and tau. PET is expensive and invasive, requiring the injection of radioactive tracers, which bind with these proteins and glow during scanning. Recently, scientists developed promising eye-scan techniques that may detect Alzheimer's disease at its earliest stage, before major symptoms appear, leading to improved management of the disease symptoms. In this review, we are discussing the visual abnormalities of Alzheimer's and other neurodegenerative diseases, focused on ocular functional-visual-structural biomarkers, retinal pathology, and potential novel diagnostic tools.
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Affiliation(s)
- Pade Colligris
- Universidad Alfonso X, Madrid, Spain
- Ocupharm Diagnostics SL, Madrid, Spain
| | | | - Basilio Colligris
- Ocupharm Diagnostics SL, Madrid, Spain
- Universidad Complutense de Madrid, Madrid, Spain
| | - Jesus Pintor
- Ocupharm Diagnostics SL, Madrid, Spain
- Universidad Complutense de Madrid, Madrid, Spain
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Allen RS, Motz CT, Feola A, Chesler KC, Haider R, Ramachandra Rao S, Skelton LA, Fliesler SJ, Pardue MT. Long-Term Functional and Structural Consequences of Primary Blast Overpressure to the Eye. J Neurotrauma 2018; 35:2104-2116. [PMID: 29648979 DOI: 10.1089/neu.2017.5394] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Acoustic blast overpressure (ABO) injury in military personnel and civilians is often accompanied by delayed visual deficits. However, most animal model studies dealing with blast-induced visual defects have focused on short-term (≤1 month) changes. Here, we evaluated long-term (≤8 months) retinal structure and function deficits in rats with ABO injury. Adult male Long-Evans rats were subjected to ABO from a single blast (approximately 190 dB SPL, ∼63 kPa, @80 psi), generated by a shock tube device. Retinal function (electroretinography; ERG), visual function (optomotor response), retinal thickness (spectral domain-optical coherence tomography; SD-OCT), and spatial cognition/exploratory motor behavior (Y-maze) were measured at 2, 4, 6, and 8 months post-blast. Immunohistochemical analysis of glial fibrillary acidic protein (GFAP) in retinal sections was performed at 8 months post-blast. Electroretinogram a- and b-waves, oscillatory potentials, and flicker responses showed greater amplitudes with delayed implicit times in both eyes of blast-exposed animals, relative to controls. Contrast sensitivity (CS) was reduced in both eyes of blast-exposed animals, whereas spatial frequency (SF) was decreased only in ipsilateral eyes, relative to controls. Total retinal thickness was greater in both eyes of blast-exposed animals, relative to controls, due to increased thickness of several retinal layers. Age, but not blast exposure, altered Y-maze outcomes. GFAP was greatly increased in blast-exposed retinas. ABO exposure resulted in visual and retinal changes that persisted up to 8 months post-blast, mimicking some of the visual deficits observed in human blast-exposed patients, thereby making this a useful model to study mechanisms of injury and potential treatments.
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Affiliation(s)
- Rachael S Allen
- 1 Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Medical Center , Atlanta, Georgia .,2 Biomedical Engineering, Georgia Institute of Technology , Atlanta, Georgia
| | - Cara T Motz
- 1 Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Medical Center , Atlanta, Georgia
| | - Andrew Feola
- 1 Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Medical Center , Atlanta, Georgia .,2 Biomedical Engineering, Georgia Institute of Technology , Atlanta, Georgia
| | - Kyle C Chesler
- 2 Biomedical Engineering, Georgia Institute of Technology , Atlanta, Georgia
| | - Raza Haider
- 1 Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Medical Center , Atlanta, Georgia
| | - Sriganesh Ramachandra Rao
- 3 Ophthalmology, Biochemistry, and Neuroscience Program, SUNY-University at Buffalo , Buffalo, New York
| | - Lara A Skelton
- 4 Research Service, VA Western NY Healthcare System , Buffalo, New York
| | - Steven J Fliesler
- 3 Ophthalmology, Biochemistry, and Neuroscience Program, SUNY-University at Buffalo , Buffalo, New York.,4 Research Service, VA Western NY Healthcare System , Buffalo, New York
| | - Machelle T Pardue
- 1 Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Medical Center , Atlanta, Georgia .,2 Biomedical Engineering, Georgia Institute of Technology , Atlanta, Georgia
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Pelak VS, Hills W. Vision in Alzheimer's disease: a focus on the anterior afferent pathway. Neurodegener Dis Manag 2018; 8:49-67. [PMID: 29359625 DOI: 10.2217/nmt-2017-0030] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Visual dysfunction has long been recognized as a manifestation of Alzheimer's disease (AD), particularly in the form of visuospatial impairment during all stages of disease. However, investigations have revealed findings within the anterior (i.e., pregeniculate) afferent visual pathways that rely on retinal imaging and electrophysiologic methodologies for detection. Here we focus on the anterior afferent visual pathways in AD and the measures used for assessment, including optical coherence tomography, electrophysiology, color vision testing and threshold visual field perimetry. A brief summary of higher order visual dysfunction is also included to allow the reader to keep in context the broader findings of afferent visual dysfunction in AD.
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Affiliation(s)
- Victoria S Pelak
- Departments of Neurology & Ophthalmology, The Rocky Mountain Lions Eye Institute, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - William Hills
- Departments of Ophthalmology & Neurology, Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA
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Doustar J, Torbati T, Black KL, Koronyo Y, Koronyo-Hamaoui M. Optical Coherence Tomography in Alzheimer's Disease and Other Neurodegenerative Diseases. Front Neurol 2017; 8:701. [PMID: 29312125 PMCID: PMC5742098 DOI: 10.3389/fneur.2017.00701] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 12/06/2017] [Indexed: 12/19/2022] Open
Abstract
Over the past decade, a surge of evidence has documented various pathological processes in the retina of patients suffering from mild cognitive impairment, Alzheimer's disease (AD), Parkinson's disease (PD), and other neurodegenerative diseases. Numerous studies have shown that the retina, a central nervous system tissue formed as a developmental outgrowth of the brain, is profoundly affected by AD. Harboring the earliest detectable disease-specific signs, amyloid β-protein (Aβ) plaques, the retina of AD patients undergoes substantial ganglion cell degeneration, thinning of the retinal nerve fiber layer, and loss of axonal projections in the optic nerve, among other abnormalities. More recent investigations described Aβ plaques in the retina located within sites of neuronal degeneration and occurring in clusters in the mid- and far-periphery of the superior and inferior quadrants, regions that had been previously overlooked. Diverse structural and/or disease-specific changes were also identified in the retina of PD, Huntington's disease, and multiple sclerosis patients. The pathological relationship between the retina and brain prompted the development of imaging tools designed to noninvasively detect and monitor these signs in living patients. One such tool is optical coherence tomography (OCT), uniquely providing high-resolution two-dimensional cross-sectional imaging and three-dimensional volumetric measurements. As such, OCT emerged as a prominent approach for assessing retinal abnormalities in vivo, and indeed provided multiple parameters that allowed for the distinction between normal aged individuals and patients with neurodegenerative diseases. Beyond the use of retinal optical fundus imaging, which recently allowed for the detection and quantification of amyloid plaques in living AD patients via a wide-field view of the peripheral retina, a major advantage of OCT has been the ability to measure the volumetric changes in specified retinal layers. OCT has proven to be particularly useful in analyzing retinal structural abnormalities consistent with disease pathogenesis. In this review, we provide a summary of OCT findings in the retina of patients with AD and other neurodegenerative diseases. Future studies should explore the combination of imaging early hallmark signs together with structural-functional biomarkers in the accessible retina as a practical means of assessing risk, disease progression, and therapeutic efficacy in these patients.
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Affiliation(s)
- Jonah Doustar
- Department of Neurosurgery, Maxine Dunitz Neurosurgical Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, United States
| | - Tania Torbati
- Department of Neurosurgery, Maxine Dunitz Neurosurgical Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, United States.,College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA, United States
| | - Keith L Black
- Department of Neurosurgery, Maxine Dunitz Neurosurgical Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, United States
| | - Yosef Koronyo
- Department of Neurosurgery, Maxine Dunitz Neurosurgical Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, United States
| | - Maya Koronyo-Hamaoui
- Department of Neurosurgery, Maxine Dunitz Neurosurgical Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, United States.,Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, United States
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