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Soucy JR, Aguzzi EA, Cho J, Gilhooley MJ, Keuthan C, Luo Z, Monavarfeshani A, Saleem MA, Wang XW, Wohlschlegel J, Baranov P, Di Polo A, Fortune B, Gokoffski KK, Goldberg JL, Guido W, Kolodkin AL, Mason CA, Ou Y, Reh TA, Ross AG, Samuels BC, Welsbie D, Zack DJ, Johnson TV. Retinal ganglion cell repopulation for vision restoration in optic neuropathy: a roadmap from the RReSTORe Consortium. Mol Neurodegener 2023; 18:64. [PMID: 37735444 PMCID: PMC10514988 DOI: 10.1186/s13024-023-00655-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 09/07/2023] [Indexed: 09/23/2023] Open
Abstract
Retinal ganglion cell (RGC) death in glaucoma and other optic neuropathies results in irreversible vision loss due to the mammalian central nervous system's limited regenerative capacity. RGC repopulation is a promising therapeutic approach to reverse vision loss from optic neuropathies if the newly introduced neurons can reestablish functional retinal and thalamic circuits. In theory, RGCs might be repopulated through the transplantation of stem cell-derived neurons or via the induction of endogenous transdifferentiation. The RGC Repopulation, Stem Cell Transplantation, and Optic Nerve Regeneration (RReSTORe) Consortium was established to address the challenges associated with the therapeutic repair of the visual pathway in optic neuropathy. In 2022, the RReSTORe Consortium initiated ongoing international collaborative discussions to advance the RGC repopulation field and has identified five critical areas of focus: (1) RGC development and differentiation, (2) Transplantation methods and models, (3) RGC survival, maturation, and host interactions, (4) Inner retinal wiring, and (5) Eye-to-brain connectivity. Here, we discuss the most pertinent questions and challenges that exist on the path to clinical translation and suggest experimental directions to propel this work going forward. Using these five subtopic discussion groups (SDGs) as a framework, we suggest multidisciplinary approaches to restore the diseased visual pathway by leveraging groundbreaking insights from developmental neuroscience, stem cell biology, molecular biology, optical imaging, animal models of optic neuropathy, immunology & immunotolerance, neuropathology & neuroprotection, materials science & biomedical engineering, and regenerative neuroscience. While significant hurdles remain, the RReSTORe Consortium's efforts provide a comprehensive roadmap for advancing the RGC repopulation field and hold potential for transformative progress in restoring vision in patients suffering from optic neuropathies.
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Affiliation(s)
- Jonathan R Soucy
- Department of Ophthalmology, Schepens Eye Research Institute of Mass. Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - Erika A Aguzzi
- The Institute of Ophthalmology, University College London, London, England, UK
| | - Julie Cho
- Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Michael James Gilhooley
- The Institute of Ophthalmology, University College London, London, England, UK
- Moorfields Eye Hospital, London, England, UK
| | - Casey Keuthan
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Ziming Luo
- Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Aboozar Monavarfeshani
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
- Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, USA
| | - Meher A Saleem
- Bascom Palmer Eye Institute, University of Miami Health System, Miami, FL, USA
| | - Xue-Wei Wang
- Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | | | - Petr Baranov
- Department of Ophthalmology, Schepens Eye Research Institute of Mass. Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - Adriana Di Polo
- Department of Neuroscience, University of Montreal, Montreal, QC, Canada
- University of Montreal Hospital Research Centre, Montreal, QC, Canada
| | - Brad Fortune
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Health, Portland, OR, USA
| | - Kimberly K Gokoffski
- Department of Ophthalmology, Roski Eye Institute, University of Southern California, Los Angeles, CA, USA
| | - Jeffrey L Goldberg
- Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - William Guido
- Department of Anatomical Sciences and Neurobiology, School of Medicine, University of Louisville, Louisville, KY, USA
| | - Alex L Kolodkin
- The Solomon H Snyder, Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Carol A Mason
- Departments of Pathology and Cell Biology, Neuroscience, and Ophthalmology, College of Physicians and Surgeons, Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
| | - Yvonne Ou
- Department of Ophthalmology, University of California, San Francisco, CA, USA
| | - Thomas A Reh
- Department of Biological Structure, University of Washington, Seattle, WA, USA
| | - Ahmara G Ross
- Departments of Ophthalmology and Neurology, University of Pennsylvania, Philadelphia, PA, USA
| | - Brian C Samuels
- Department of Ophthalmology and Visual Sciences, Callahan Eye Hospital, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Derek Welsbie
- Shiley Eye Institute and Viterbi Family Department of Ophthalmology, University of California, San Diego, CA, USA
| | - Donald J Zack
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, 21287 MD, USA
- Departments of Neuroscience, Molecular Biology & Genetics, and Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Thomas V Johnson
- Departments of Neuroscience, Molecular Biology & Genetics, and Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
- Cellular & Molecular Medicine Program, Johns Hopkins University School of Medicine, Baltimore, 21287 MD, USA.
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Phenotype Characterization of a Mice Genetic Model of Absolute Blindness. Int J Mol Sci 2022; 23:ijms23158152. [PMID: 35897728 PMCID: PMC9331777 DOI: 10.3390/ijms23158152] [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: 06/23/2022] [Revised: 07/19/2022] [Accepted: 07/22/2022] [Indexed: 11/17/2022] Open
Abstract
Recent technological development requires new approaches to address the problem of blindness. Such approaches need to be able to ensure that no cells with photosensitive capability remain in the retina. The presented model, Opn4−/− × Pde6brd10/rd10 (O×Rd) double mutant murine, is a combination of a mutation in the Pde6b gene (photoreceptor degeneration) together with a deletion of the Opn4 gene (responsible for the expression of melanopsin in the intrinsically photosensitive retinal ganglion cells). This model has been characterized and compared with those of WT mice and murine animal models displaying both mutations separately. A total loss of pupillary reflex was observed. Likewise, behavioral tests demonstrated loss of rejection to illuminated spaces and a complete decrease in visual acuity (optomotor test). Functional recordings showed an absolute disappearance of various wave components of the full-field and pattern electroretinogram (fERG, pERG). Likewise, visual evoked potential (VEP) could not be recorded. Immunohistochemical staining showed marked degeneration of the outer retinal layers and the absence of melanopsin staining. The combination of both mutations has generated an animal model that does not show any photosensitive element in its retina. This model is a potential tool for the study of new ophthalmological approaches such as optosensitive agents.
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Differential susceptibility of retinal ganglion cell subtypes against neurodegenerative diseases. Graefes Arch Clin Exp Ophthalmol 2022; 260:1807-1821. [PMID: 35038014 DOI: 10.1007/s00417-022-05556-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 11/27/2021] [Accepted: 01/06/2022] [Indexed: 12/15/2022] Open
Abstract
Retinal ganglion cells (RGCs) are essential to propagate external visual information from the retina to the brain. Death of RGCs is speculated to be closely correlated with blinding retinal diseases, such as glaucoma and traumatic optic neuropathy (TON). Emerging innovative technologies have helped refine and standardize the classification of RGCs; at present, they are classified into more than 40 subpopulations in mammals. These RGC subtypes are identified by a combination of anatomical morphologies, electrophysiological functions, and genetic profiles. Increasing evidence suggests that neurodegenerative diseases do not collectively affect the RGCs. In fact, which RGC subtype exhibits the strongest or weakest susceptibility is hotly debated. Although a consensus has not yet been reached, it is certain that assorted RGCs display differential susceptibility against irreversible degeneration. Interestingly, a single RGC subtype can exhibit various vulnerabilities to optic nerve damage in diverse injury models. Thus, elucidating how susceptible RGC subtypes are to various injuries can protect vulnerable RGCs from damage and improve the possibility of preventing and treating visual impairment caused by neurodegenerative diseases. In this review, we summarize in detail the progress and status quo of research on the type-specific susceptibility of RGCs and point out current limitations and the possible directions for future research in this field.
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Del Dotto V, Carelli V. Dominant Optic Atrophy (DOA): Modeling the Kaleidoscopic Roles of OPA1 in Mitochondrial Homeostasis. Front Neurol 2021; 12:681326. [PMID: 34177786 PMCID: PMC8220150 DOI: 10.3389/fneur.2021.681326] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 04/22/2021] [Indexed: 02/05/2023] Open
Abstract
In the year 2000, the discovery of OPA1 mutations as causative for dominant optic atrophy (DOA) was pivotal to rapidly expand the field of mitochondrial dynamics and describe the complex machinery governing this pathway, with a multitude of other genes and encoded proteins involved in neurodegenerative disorders of the optic nerve. OPA1 turned out to be a much more complex protein than initially envisaged, connecting multiple pathways beyond its strict role in mitochondrial fusion, such as sensing of OXPHOS needs and mitochondrial DNA maintenance. As a consequence, an increasing need to investigate OPA1 functions at multiple levels has imposed the development of multiple tools and models that are here reviewed. Translational mitochondrial medicine, with the ultimate objective of translating basic science necessary to understand pathogenic mechanisms into therapeutic strategies, requires disease modeling at multiple levels: from the simplest, like in yeast, to cell models, including the increasing use of reprogrammed stem cells (iPSCs) from patients, to animal models. In the present review, we thoroughly examine and provide the state of the art of all these approaches.
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Affiliation(s)
- Valentina Del Dotto
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
| | - Valerio Carelli
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy.,Istituto di Ricovero e Cura a Carattere Scientifico Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, Bologna, Italy
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Sun S, Erchova I, Sengpiel F, Votruba M. Opa1 Deficiency Leads to Diminished Mitochondrial Bioenergetics With Compensatory Increased Mitochondrial Motility. Invest Ophthalmol Vis Sci 2021; 61:42. [PMID: 32561926 PMCID: PMC7415319 DOI: 10.1167/iovs.61.6.42] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Purpose Retinal ganglion cells (RGCs) are susceptible to mitochondrial deficits and also the major cell type affected in patients with mutations in the OPA1 gene in autosomal dominant optic atrophy (ADOA). Here, we characterized mitochondria in RGCs in vitro from a heterozygous B6; C3-Opa1Q285STOP (Opa1+/−) mouse model to investigate mitochondrial changes underlying the pathology in ADOA. Methods Mouse RGCs were purified from wild-type and Opa1+/− mouse retina by two-step immunopanning. The mitochondria in neurites of RGCs were labeled with MitoTracker Red for structure and motility measurement by time-lapse imaging. Mitochondrial bioenergetics were determined by the real-time measurement of oxygen consumption rate using a Seahorse XFe 96 Extracellular Flux Analyzer. Results We observed a significant decrease in mitochondrial length in Opa1+/− RGCs with a remarkably higher proportion and density of motile mitochondria along the neurites. We also observed an increased transport velocity with a higher number of contacts between mitochondria in Opa1+/− RGC neurites. The oxygen consumption assays showed a severe impairment in basal respiration, Adenosine triphosphate-linked (ATP-linked) oxygen consumption, as well as reserve respiratory capacity, in RGCs from Opa1+/− mouse retina. Conclusions Opa1 deficiency leads to significant fragmentation of mitochondrial morphology, activation of mitochondrial motility and impaired respiratory function in RGCs from the B6; C3-Opa1Q285STOP mouse model. This highlights the significant alterations in the intricate interplay between mitochondrial morphology, motility, and energy production in RGCs with Opa1 deficiency long before the onset of clinical symptoms of the pathology.
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Kim US, Mahroo OA, Mollon JD, Yu-Wai-Man P. Retinal Ganglion Cells-Diversity of Cell Types and Clinical Relevance. Front Neurol 2021; 12:661938. [PMID: 34093409 PMCID: PMC8175861 DOI: 10.3389/fneur.2021.661938] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Accepted: 04/06/2021] [Indexed: 11/24/2022] Open
Abstract
Retinal ganglion cells (RGCs) are the bridging neurons that connect the retinal input to the visual processing centres within the central nervous system. There is a remarkable diversity of RGCs and the various subtypes have unique morphological features, distinct functions, and characteristic pathways linking the inner retina to the relevant brain areas. A number of psychophysical and electrophysiological tests have been refined to investigate this large and varied population of RGCs. Technological advances, such as high-resolution optical coherence tomography imaging, have provided additional tools to define the pattern of RGC involvement and the chronological sequence of events in both inherited and acquired optic neuropathies. The mechanistic insights gained from these studies, in particular the selective vulnerability and relative resilience of particular RGC subtypes, are of fundamental importance as they are directly relevant to the development of targeted therapies for these invariably progressive blinding diseases. This review provides a comprehensive description of the various types of RGCs, the developments in proposed methods of classification, and the current gaps in our knowledge of how these RGCs are differentially affected depending on the underlying aetiology. The synthesis of the current body of knowledge on the diversity of RGCs and the pathways that are potentially amenable to therapeutic modulation will hopefully lead to much needed effective treatments for patients with optic neuropathies.
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Affiliation(s)
- Ungsoo Samuel Kim
- Kim's Eye Hospital, Seoul, South Korea
- John van Geest Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
- Cambridge Eye Unit, Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, United Kingdom
- Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom
- *Correspondence: Ungsoo Samuel Kim
| | - Omar A. Mahroo
- Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom
- Institute of Ophthalmology, University College London, London, United Kingdom
- Section of Ophthalmology, King's College London, St. Thomas' Hospital Campus, London, United Kingdom
| | - John D. Mollon
- Department of Psychology, University of Cambridge, Cambridge, United Kingdom
| | - Patrick Yu-Wai-Man
- John van Geest Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
- Cambridge Eye Unit, Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, United Kingdom
- Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom
- Institute of Ophthalmology, University College London, London, United Kingdom
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7
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La Morgia C, Carelli V, Carbonelli M. Melanopsin Retinal Ganglion Cells and Pupil: Clinical Implications for Neuro-Ophthalmology. Front Neurol 2018; 9:1047. [PMID: 30581410 PMCID: PMC6292931 DOI: 10.3389/fneur.2018.01047] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Accepted: 11/19/2018] [Indexed: 02/02/2023] Open
Abstract
Melanopsin retinal ganglion cells (mRGCs) are intrinsically photosensitive RGCs that mediate many relevant non-image forming functions of the eye, including the pupillary light reflex, through the projections to the olivary pretectal nucleus. In particular, the post-illumination pupil response (PIPR), as evaluated by chromatic pupillometry, can be used as a reliable marker of mRGC function in vivo. In the last years, pupillometry has become a promising tool to assess mRGC dysfunction in various neurological and neuro-ophthalmological conditions. In this review we will present the most relevant findings of pupillometric studies in glaucoma, hereditary optic neuropathies, ischemic optic neuropathies, idiopathic intracranial hypertension, multiple sclerosis, Parkinson's disease, and mood disorders. The use of PIPR as a marker for mRGC function is also proposed for other neurodegenerative disorders in which circadian dysfunction is documented.
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Affiliation(s)
- Chiara La Morgia
- Unità Operativa Complessa Clinica Neurologica, IRCCS Istituto delle Scienze Neurologiche di Bologna, Ospedale Bellaria, Bologna, Italy.,Dipartimento di Scienze Biomediche e Neuromotorie, Università di Bologna, Bologna, Italy
| | - Valerio Carelli
- Unità Operativa Complessa Clinica Neurologica, IRCCS Istituto delle Scienze Neurologiche di Bologna, Ospedale Bellaria, Bologna, Italy.,Dipartimento di Scienze Biomediche e Neuromotorie, Università di Bologna, Bologna, Italy
| | - Michele Carbonelli
- Unità Operativa Complessa Clinica Neurologica, IRCCS Istituto delle Scienze Neurologiche di Bologna, Ospedale Bellaria, Bologna, Italy
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8
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Douglas RH. The pupillary light responses of animals; a review of their distribution, dynamics, mechanisms and functions. Prog Retin Eye Res 2018; 66:17-48. [PMID: 29723580 DOI: 10.1016/j.preteyeres.2018.04.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 04/24/2018] [Accepted: 04/25/2018] [Indexed: 11/28/2022]
Abstract
The timecourse and extent of changes in pupil area in response to light are reviewed in all classes of vertebrate and cephalopods. Although the speed and extent of these responses vary, most species, except the majority of teleost fish, show extensive changes in pupil area related to light exposure. The neuromuscular pathways underlying light-evoked pupil constriction are described and found to be relatively conserved, although the precise autonomic mechanisms differ somewhat between species. In mammals, illumination of only one eye is known to cause constriction in the unilluminated pupil. Such consensual responses occur widely in other animals too, and their function and relation to decussation of the visual pathway is considered. Intrinsic photosensitivity of the iris muscles has long been known in amphibia, but is in fact widespread in other animals. The functions of changes in pupil area are considered. In the majority of species, changes in pupil area serve to balance the conflicting demands of high spatial acuity and increased sensitivity in different light levels. In the few teleosts in which pupil movements occur they do not serve a visual function but play a role in camouflaging the eye of bottom-dwelling species. The occurrence and functions of the light-independent changes in pupil size displayed by many animals are also considered. Finally, the significance of the variations in pupil shape, ranging from circular to various orientations of slits, ovals, and other shapes, is discussed.
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Affiliation(s)
- Ronald H Douglas
- Division of Optometry & Visual Science City, University of London, Northampton Square, London, EC1V 0HB, United Kingdom.
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9
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Finsterer J, Mancuso M, Pareyson D, Burgunder JM, Klopstock T. Mitochondrial disorders of the retinal ganglion cells and the optic nerve. Mitochondrion 2017; 42:1-10. [PMID: 29054473 DOI: 10.1016/j.mito.2017.10.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 10/02/2017] [Accepted: 10/06/2017] [Indexed: 12/13/2022]
Abstract
OBJECTIVES To summarise and discuss recent findings and future perspectives concerning mitochondrial disorders (MIDs) affecting the retinal ganglion cells and the optic nerve (mitochondrial optic neuropathy. MON). METHOD Literature review. RESULTS MON in MIDs is more frequent than usually anticipated. MON may occur in specific as well as non-specific MIDs. In specific and non-specific MIDs, MON may be a prominent or non-prominent phenotypic feature and due to mutations in genes located either in the mitochondrial DNA (mtDNA) or the nuclear DNA (nDNA). Clinically, MON manifests with painless, bilateral or unilateral, slowly or rapidly progressive visual impairment and visual field defects. In some cases, visual impairment may spontaneously recover. The most frequent MIDs with MON include LHON due to mutations in mtDNA-located genes and autosomal dominant optic atrophy (ADOA) or autosomal recessive optic atrophy (AROA) due to mutations in nuclear genes. Instrumental investigations for diagnosing MON include fundoscopy, measurement of visual acuity, visual fields, and color vision, visually-evoked potentials, optical coherence tomography, fluorescein angiography, electroretinography, and MRI of the orbita and cerebrum. In non-prominent MON, work-up of the muscle biopsy with transmission electron microscopy may indicate mitochondrial destruction. Treatment is mostly supportive but idebenone has been approved for LHON and experimental approaches are promising. CONCLUSIONS MON needs to be appreciated, requires extensive diagnostic work-up, and supportive treatment should be applied although loss of vision, as the most severe outcome, can often not be prevented.
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Affiliation(s)
| | - Michelangelo Mancuso
- Department of Clinical and Experimental Medicine, Neurological Clinic, University of Pisa, Italy
| | - Davide Pareyson
- Department of Clinical Neurosciences, C. Besta Neurological Institute, IRCCS Foundation, Milan, Italy.
| | - Jean-Marc Burgunder
- Department of Neurology, University of Bern, Switzerland; Department of Neurology, Sun Yat Sen University, Guangzhou, China; Department of Neurology, Sichuan University, Chendgu, China.
| | - Thomas Klopstock
- Department of Neurology, Friedrich-Baur Institute, Ludwig-Maximilians-Universität München, Munich, Germany; German Center for Neurodegenerative Diseases (DZNE), Munich, Germany; Munich Cluster for Systems Neurology (SyNergy), Munich, Germany.
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10
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Ba-Ali S, Lund-Andersen H. Pupillometric evaluation of the melanopsin containing retinal ganglion cells in mitochondrial and non-mitochondrial optic neuropathies. Mitochondrion 2017; 36:124-129. [PMID: 28716667 DOI: 10.1016/j.mito.2017.07.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 05/29/2017] [Accepted: 07/13/2017] [Indexed: 01/08/2023]
Abstract
In recent years, chromatic pupillometry is used in humans to evaluate the activity of melanopsin expressing intrinsic photosensitive retinal ganglion cells (ipRGCs). Blue light is used to stimulate the ipRGCs and red light activates the rod/cone photoreceptors. The late re-dilation phase of pupillary light reflex is primarily driven by the ipRGCs. Optic neuropathies i.e. Leber hereditary optic neuropathy (LHON), autosomal dominant optic atrophy (ADOA), nonarteritic anterior ischemic optic neuropathy (NAION), glaucoma, optic neuritis and idiopathic intracranial hypertension (IIH) are among the diseases, which have been subject to pupillometric studies. The ipRGCs are differentially affected in these various optic neuropathies. In mitochondrial optic neuropathies, the ipRGCs are protected against degeneration, whereas in glaucoma, NAION, optic neuritis and IIH the ipRGCs are damaged. Here, we will review the results of pupillometric, histopathological and animal studies evaluating the ipRGCs in mitochondrial and non-mitochondrial optic neuropathies.
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Affiliation(s)
- Shakoor Ba-Ali
- Department of Ophthalmology, Rigshospitalet, Glostrup, Denmark; Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | - Henrik Lund-Andersen
- Department of Ophthalmology, Rigshospitalet, Glostrup, Denmark; Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Georg B, Ghelli A, Giordano C, Ross-Cisneros FN, Sadun AA, Carelli V, Hannibal J, La Morgia C. Melanopsin-expressing retinal ganglion cells are resistant to cell injury, but not always. Mitochondrion 2017; 36:77-84. [PMID: 28412540 DOI: 10.1016/j.mito.2017.04.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 03/14/2017] [Accepted: 04/07/2017] [Indexed: 12/12/2022]
Abstract
Melanopsin retinal ganglion cells (mRGCs) are intrinsically photosensitive RGCs deputed to non-image forming functions of the eye such as synchronization of circadian rhythms to light-dark cycle. These cells are characterized by unique electrophysiological, anatomical and biochemical properties and are usually more resistant than conventional RGCs to different insults, such as axotomy and different paradigms of stress. We also demonstrated that these cells are relatively spared compared to conventional RGCs in mitochondrial optic neuropathies (Leber's hereditary optic neuropathy and Dominant Optic Atrophy). However, these cells are affected in other neurodegenerative conditions, such as glaucoma and Alzheimer's disease. We here review the current evidences that may underlie this dichotomy. We also present our unpublished data on cell experiments demonstrating that melanopsin itself does not explain the robustness of these cells and some preliminary data on immunohistochemical assessment of mitochondria in mRGCs.
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Affiliation(s)
- Birgitte Georg
- Department of Clinical Biochemistry, Bispebjerg and Frederiksberg Hospital, Faculty Health Sciences, University of Copenhagen, Denmark
| | - Anna Ghelli
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy
| | - Carla Giordano
- Department of Radiology, Oncology and Pathology, Sapienza, University of Rome, Rome, Italy
| | | | - Alfredo A Sadun
- Doheny Eye Institute, Los Angeles, CA, USA; Department of Ophthalmology, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA, USA
| | - Valerio Carelli
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy; Department of Biomedical and Neuromotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | - Jens Hannibal
- Department of Clinical Biochemistry, Bispebjerg and Frederiksberg Hospital, Faculty Health Sciences, University of Copenhagen, Denmark.
| | - Chiara La Morgia
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy; Department of Biomedical and Neuromotor Sciences (DIBINEM), University of Bologna, Bologna, Italy.
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12
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Park JC, Moss HE, McAnany JJ. The Pupillary Light Reflex in Idiopathic Intracranial Hypertension. Invest Ophthalmol Vis Sci 2016; 57:23-9. [PMID: 26746015 PMCID: PMC4713014 DOI: 10.1167/iovs.15-18181] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Purpose To evaluate the effects of idiopathic intracranial hypertension (IIH) on rod-, cone-, and melanopsin-mediated pupillary light reflexes (PLRs). Methods Pupillary light reflexes elicited by full-field, brief-flash stimuli were recorded in 13 IIH patients and 13 normal controls. Subjects were dark-adapted for 10 minutes and the PLR was recorded in response to short-wavelength flashes (0.001 cd/m2: rod condition; 450 cd/m2: melanopsin condition). Subjects were then exposed to a rod-suppressing field and 10 cd/m2 long-wavelength flashes were presented (cone condition). Pupillary light reflexes were quantified as the maximum transient constriction (rod and cone conditions) and the post-illumination pupil constriction (melanopsin condition), relative to the baseline pupil size. Diagnostic power was evaluated using receiver operating characteristic (ROC) analysis. Results The IIH patients had significantly smaller PLRs under the melanopsin (P < 0.001) and rod (P = 0.04) paradigms; a trend for reduced cone-mediated PLRs was also found (P = 0.08). Receiver operating characteristic analysis indicated areas under the curves (AUC) of 0.83 (melanopsin-meditated; P = 0.001), 0.71 (rod-mediated; P = 0.07), and 0.77 (cone-mediated; P = 0.02). The AUC (0.90, P < 0.001), sensitivity (85%), and specificity (85%) were high for ROC analysis performed on the mean of the rod, cone, and melanopsin PLRs. Conclusions Pupillary light reflex reductions in IIH patients indicate compromised RGC function. PLR measurement, particularly under rod- and melanopsin-mediated conditions, may be a useful adjunct to standard clinical measures of visual function in IIH.
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Affiliation(s)
- Jason C Park
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois, United States
| | - Heather E Moss
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois, United States 2Department of Neurology & Rehabilitation, University of Illinois at Chicago, Chicago, Illinois, United States
| | - J Jason McAnany
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois, United States 3Department of Psychology, University of Illinois at Chicago, Chicago, Illinois, United States 4Department of Bioengineering, University o
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Münch M, Léon L, Collomb S, Kawasaki A. Comparison of acute non-visual bright light responses in patients with optic nerve disease, glaucoma and healthy controls. Sci Rep 2015; 5:15185. [PMID: 26478261 PMCID: PMC4609937 DOI: 10.1038/srep15185] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 09/22/2015] [Indexed: 11/30/2022] Open
Abstract
This study examined the effect of optic nerve disease, hence retinal ganglion cell loss, on non-visual functions related to melanopsin signalling. Test subjects were patients with bilateral visual loss and optic atrophy from either hereditary optic neuropathy (n = 11) or glaucoma (n = 11). We measured melatonin suppression, subjective sleepiness and cognitive functions in response to bright light exposure in the evening. We also quantified the post-illumination pupil response to a blue light stimulus. All results were compared to age-matched controls (n = 22). Both groups of patients showed similar melatonin suppression when compared to their controls. Greater melatonin suppression was intra-individually correlated to larger post-illumination pupil response in patients and controls. Only the glaucoma patients demonstrated a relative attenuation of their pupil response. In addition, they were sleepier with slower reaction times during nocturnal light exposure. In conclusion, glaucomatous, but not hereditary, optic neuropathy is associated with reduced acute light effects. At mild to moderate stages of disease, this is detected only in the pupil function and not in responses conveyed via the retinohypothalamic tract such as melatonin suppression.
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Affiliation(s)
- M Münch
- Solar Energy and Building Physics Laboratory, Environmental and Civil Engineering Institute, Swiss Federal Institute of Technology, Lausanne, Switzerland
| | - L Léon
- University of Lausanne, Hôpital Ophtalmique Jules-Gonin, Lausanne, Switzerland
| | - S Collomb
- University of Lausanne, Hôpital Ophtalmique Jules-Gonin, Lausanne, Switzerland
| | - A Kawasaki
- University of Lausanne, Hôpital Ophtalmique Jules-Gonin, Lausanne, Switzerland
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Differential monocular vs. binocular pupil responses from melanopsin-based photoreception in patients with anterior ischemic optic neuropathy. Sci Rep 2015; 5:10780. [PMID: 26074032 PMCID: PMC4466591 DOI: 10.1038/srep10780] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 05/05/2015] [Indexed: 01/05/2023] Open
Abstract
We examined the effect of anterior ischemic optic neuropathy (AION) on the activity of intrinsically photosensitive retinal ganglion cells (ipRGCs) using the pupil as proxy. Eighteen patients with AION (10 unilateral, 8 bilateral) and 29 age-matched control subjects underwent chromatic pupillometry. Red and blue light stimuli increasing in 0.5 log steps were presented to each eye independently under conditions of dark and light adaptation. The recorded pupil contraction was plotted against stimulus intensity to generate scotopic and photopic response curves for assessment of synaptically-mediated ipRGC activity. Bright blue light stimuli presented monocularly and binocularly were used for melanopsin activation. The post-stimulus pupil size (PSPS) at the 6th second following stimulus offset was the marker of intrinsic ipRGC activity. Finally, questionnaires were administered to assess the influence of ipRGCs on sleep. The pupil response and PSPS to all monocularly-presented light stimuli were impaired in AION eyes, indicating ipRGC dysfunction. To binocular light stimulation, the PSPS of AION patients was similar to that of controls. There was no difference in the sleep habits of the two groups. Thus after ischemic injury to one or both optic nerves, the summated intrinsic ipRGC activity is preserved when both eyes receive adequate light exposure.
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Nissen C, Rönnbäck C, Sander B, Herbst K, Milea D, Larsen M, Lund-Andersen H. Dissociation of Pupillary Post-Illumination Responses from Visual Function in Confirmed OPA1 c.983A > G and c.2708_2711delTTAG Autosomal Dominant Optic Atrophy. Front Neurol 2015; 6:5. [PMID: 25699009 PMCID: PMC4316714 DOI: 10.3389/fneur.2015.00005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 01/09/2015] [Indexed: 12/03/2022] Open
Abstract
Purpose: To test whether the melanopsin-containing, intrinsically photosensitive retinal ganglion cells (ipRGCs), as evaluated by examination of the pupillary light reflex (PLR), are preserved in genetically confirmed autosomal dominant optic atrophy (ADOA). Method: Twenty-nine patients with either the c.983A > G (n = 14) or the c.2708_ 2711delTTAG mutation (n = 15) were examined with monochromatic pupillometry, using isoluminant (300 cd/m2), red (660 nm) or blue (470 nm) light, optical coherence tomography, automated visual field analysis, and with determination of best corrected visual acuity (BCVA). Since we examined two different mutations, initially we compared all outcome variables between the two, and finding no statistically significant difference, pooled them. Results: Despite a poor BCVA (56 letters, ETDRS) in the ADOA patients, their post-illuminatory pupil responses did not differ significantly from those of healthy controls (blue, p = 0.45, red, p = 0.49, t-test), and no statistically significant effect was noted of peripapillary retinal nerve fiber layer thickness, ganglion cell-inner plexiform layer thickness, or age. Conclusion: The PLR to blue light of high luminance (300 cd/m2) was preserved in both c.983A > G and c.2708_2711delTTAG ADOA despite severe visual loss and optic nerve atrophy. The study confirms, in a large sample of two genetically homogenous groups, that the ipRGCs are spared in ADOA.
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Affiliation(s)
- Claus Nissen
- Department of Ophthalmology, Glostrup Hospital, University of Copenhagen , Copenhagen , Denmark
| | - Cecilia Rönnbäck
- Department of Ophthalmology, Glostrup Hospital, University of Copenhagen , Copenhagen , Denmark
| | - Birgit Sander
- Department of Ophthalmology, Glostrup Hospital, University of Copenhagen , Copenhagen , Denmark
| | - Kristina Herbst
- Department of Ophthalmology, Glostrup Hospital, University of Copenhagen , Copenhagen , Denmark
| | - Dan Milea
- Department of Ophthalmology, Glostrup Hospital, University of Copenhagen , Copenhagen , Denmark ; Singapore National Eye Centre, Singapore Eye Research Institute, Duke-NUS Graduate Medical School Singapore , Singapore , Singapore ; Angers University Hospital , Angers , France
| | - Michael Larsen
- Department of Ophthalmology, Glostrup Hospital, University of Copenhagen , Copenhagen , Denmark
| | - Henrik Lund-Andersen
- Department of Ophthalmology, Glostrup Hospital, University of Copenhagen , Copenhagen , Denmark
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16
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Cui Q, Ren C, Sollars PJ, Pickard GE, So KF. The injury resistant ability of melanopsin-expressing intrinsically photosensitive retinal ganglion cells. Neuroscience 2014; 284:845-853. [PMID: 25446359 PMCID: PMC4637166 DOI: 10.1016/j.neuroscience.2014.11.002] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 10/17/2014] [Accepted: 11/04/2014] [Indexed: 12/19/2022]
Abstract
Neurons in the mammalian retina expressing the photopigment melanopsin have been identified as a class of intrinsically photosensitive retinal ganglion cells (ipRGCs). This discovery more than a decade ago has opened up an exciting new field of retinal research, and following the initial identification of photosensitive ganglion cells, several subtypes have been described. A number of studies have shown that ipRGCs subserve photoentrainment of circadian rhythms. They also influence other non-image forming functions of the visual system, such as the pupillary light reflex, sleep, cognition, mood, light aversion and development of the retina. These novel photosensitive neurons also influence form vision by contributing to contrast detection. Furthermore, studies have shown that ipRGCs are more injury-resistant following optic nerve injury, in animal models of glaucoma, and in patients with mitochondrial optic neuropathies, i.e., Leber’s hereditary optic neuropathy and dominant optic atrophy. There is also an indication that these cells may be resistant to glutamate-induced excitotoxicity. Herein we provide an overview of ipRGCs and discuss the injury-resistant character of these neurons under certain pathological and experimental conditions.
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Affiliation(s)
- Q Cui
- Guangdong-HongKong-Macau Institute of CNS Regeneration, Jinan University, Guangdong, PR China; Guangdong Medical Key Laboratory of Brain Function and Diseases, Jinan University, Guangzhou, PR China; GHM Collaboration and Innovation Center for Tissue Regeneration and Repair, Jinan University, Guangzhou, PR China
| | - C Ren
- Guangdong-HongKong-Macau Institute of CNS Regeneration, Jinan University, Guangdong, PR China; Guangdong Medical Key Laboratory of Brain Function and Diseases, Jinan University, Guangzhou, PR China; GHM Collaboration and Innovation Center for Tissue Regeneration and Repair, Jinan University, Guangzhou, PR China
| | - P J Sollars
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska, Lincoln, NE 68583, USA
| | - G E Pickard
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska, Lincoln, NE 68583, USA; Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - K-F So
- Guangdong-HongKong-Macau Institute of CNS Regeneration, Jinan University, Guangdong, PR China; Guangdong Medical Key Laboratory of Brain Function and Diseases, Jinan University, Guangzhou, PR China; GHM Collaboration and Innovation Center for Tissue Regeneration and Repair, Jinan University, Guangzhou, PR China; Department of Ophthalmology, University of Hong Kong, Hong Kong.
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González Fleitas MF, Bordone M, Rosenstein RE, Dorfman D. Effect of retinal ischemia on the non-image forming visual system. Chronobiol Int 2014; 32:152-63. [PMID: 25238585 DOI: 10.3109/07420528.2014.959526] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Retinal ischemic injury is an important cause of visual impairment. The loss of retinal ganglion cells (RGCs) is a key sign of retinal ischemic damage. A subset of RGCs expressing the photopigment melanopsin (mRGCs) regulates non-image-forming visual functions such as the pupillary light reflex (PLR), and circadian rhythms. We studied the effect of retinal ischemia on mRGCs and the non-image-forming visual system function. For this purpose, transient ischemia was induced by raising intraocular pressure to 120 mm Hg for 40 min followed by retinal reperfusion by restoring normal pressure. At 4 weeks post-treatment, animals were subjected to electroretinography and histological analysis. Ischemia induced a significant retinal dysfunction and histological alterations. At this time point, a significant decrease in the number of Brn3a(+) RGCs and in the anterograde transport from the retina to the superior colliculus and lateral geniculate nucleus was observed, whereas no differences in the number of mRGCs, melanopsin levels, and retinal projections to the suprachiasmatic nuclei and the olivary pretectal nucleus were detected. At low light intensity, a decrease in pupil constriction was observed in intact eyes contralateral to ischemic eyes, whereas at high light intensity, retinal ischemia did not affect the consensual PLR. Animals with ischemia in both eyes showed a conserved locomotor activity rhythm and a photoentrainment rate which did not differ from control animals. These results suggest that the non-image forming visual system was protected against retinal ischemic damage.
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Affiliation(s)
- María Florencia González Fleitas
- Laboratorio de Neuroquímica Retiniana y Oftalmología Experimental, Departamento de Bioquímica Humana, Facultad de Medicina/CEFyBO, Universidad de Buenos Aires/CONICET , Buenos Aires , Argentina
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La Morgia C, Carbonelli M, Barboni P, Sadun AA, Carelli V. Medical management of hereditary optic neuropathies. Front Neurol 2014; 5:141. [PMID: 25132831 PMCID: PMC4117178 DOI: 10.3389/fneur.2014.00141] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 07/16/2014] [Indexed: 01/31/2023] Open
Abstract
Hereditary optic neuropathies are diseases affecting the optic nerve. The most common are mitochondrial hereditary optic neuropathies, i.e., the maternally inherited Leber's hereditary optic neuropathy (LHON) and dominant optic atrophy (DOA). They both share a mitochondrial pathogenesis that leads to the selective loss of retinal ganglion cells and axons, in particular of the papillo-macular bundle. Typically, LHON is characterized by an acute/subacute loss of central vision associated with impairment of color vision and swelling of retinal nerve fibers followed by optic atrophy. DOA, instead, is characterized by a childhood-onset and slowly progressive loss of central vision, worsening over the years, leading to optic atrophy. The diagnostic workup includes neuro-ophthalmologic evaluation and genetic testing of the three most common mitochondrial DNA mutations affecting complex I (11778/ND4, 3460/ND1, and 14484/ND6) for LHON and sequencing of the nuclear gene OPA1 for DOA. Therapeutic strategies are still limited including agents that bypass the complex I defect and exert an antioxidant effect (idebenone). Further strategies are aimed at stimulating compensatory mitochondrial biogenesis. Gene therapy is also a promising avenue that still needs to be validated.
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Affiliation(s)
- Chiara La Morgia
- UOC Clinica Neurologica, IRCCS Istituto delle Scienze Neurologiche di Bologna, Ospedale Bellaria , Bologna , Italy ; Unità di Neurologia, Dipartimento di Scienze Biomediche e NeuroMotorie (DIBINEM), Università di Bologna , Bologna , Italy
| | | | - Piero Barboni
- Studio Oculistico d'Azeglio , Bologna , Italy ; Istituto Scientifico San Raffaele , Milan , Italy
| | - Alfredo Arrigo Sadun
- Doheny Eye Institute, University of California Los Angeles , Los Angeles, CA , USA
| | - Valerio Carelli
- UOC Clinica Neurologica, IRCCS Istituto delle Scienze Neurologiche di Bologna, Ospedale Bellaria , Bologna , Italy ; Unità di Neurologia, Dipartimento di Scienze Biomediche e NeuroMotorie (DIBINEM), Università di Bologna , Bologna , Italy
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19
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Mitochondrial dysfunction affecting visual pathways. Rev Neurol (Paris) 2014; 170:344-54. [DOI: 10.1016/j.neurol.2014.03.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 03/08/2014] [Accepted: 03/26/2014] [Indexed: 01/08/2023]
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Moura ALA, Nagy BV, La Morgia C, Barboni P, Oliveira AGF, Salomão SR, Berezovsky A, de Moraes-Filho MN, Chicani CF, Belfort R, Carelli V, Sadun AA, Hood DC, Ventura DF. The pupil light reflex in Leber's hereditary optic neuropathy: evidence for preservation of melanopsin-expressing retinal ganglion cells. Invest Ophthalmol Vis Sci 2013; 54:4471-7. [PMID: 23737476 DOI: 10.1167/iovs.12-11137] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To investigate the pupillary light reflex (PLR) of patients with severe loss of vision due to Leber's Hereditary Optic Neuropathy (LHON) in the context of a proposed preservation of melanopsin-expressing retinal ganglion cells (mRGCs). METHODS Ten LHON patients (7 males; 51.6 ± 14.1 years), with visual acuities ranging from 20/400 to hand motion perception and severe visual field losses, were tested and compared with 16 healthy subjects (7 males; 42.15 ± 15.4 years) tested as controls. PLR was measured with an eye tracker and the stimuli were controlled with a Ganzfeld system. Pupil responses were measured monocularly, to 1 second of blue (470 nm) and red (640 nm) flashes with 1, 10, 100, and 250 cd/m² luminances. The normalized amplitude of peak of the transient PLR and the amplitude of the sustained PLR at 6 seconds after the flash offset were measured. In addition, optical coherence topography (OCT) scans of the peripapillary retinal nerve fiber layer were obtained. RESULTS The patient's peak PLR responses were on average 15% smaller than controls (P < 0.05), but 5 out of 10 patients had amplitudes within the range of controls. The patients' sustained PLRs were comparable with controls at lower flash intensities, but on average, 27% smaller to the 250 cd/m² blue light, although there was considerable overlap with the PLR amplitudes of control. All patients had severe visual field losses and the retinal nerve fiber layer thickness was reduced to a minimum around the optic disc in 8 of the 10 patients. CONCLUSIONS The PLR is maintained overall in LHON patients despite the severity of optic atrophy. These results are consistent with previous evidence of selective preservation of mRGCs.
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Affiliation(s)
- Ana Laura A Moura
- Instituto de Psicologia, Universidade de São Paulo, São Paulo, Brazil.
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