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Revue Medicale de Liege Feb 2020Retinitis pigmentosa is the most frequent hereditary dystrophy of the retina, with a global prevalence of 1/4.000. The underlying mechanism involves progressive loss,...
Retinitis pigmentosa is the most frequent hereditary dystrophy of the retina, with a global prevalence of 1/4.000. The underlying mechanism involves progressive loss, first of the rod photoreceptor cells, followed by the cone photoreceptor cells. Finally, complete blindness may occur. Genetic transmission is known but most cases are sporadic. Few effective treatments exist nowadays and hence regular follow-up is required in a revalidation center.
Topics: Humans; Retina; Retinal Cone Photoreceptor Cells; Retinal Rod Photoreceptor Cells; Retinitis Pigmentosa
PubMed: 32030928
DOI: No ID Found -
International Journal of Molecular... Apr 2023Retinitis pigmentosa (RP) comprises a group of inherited retinal dystrophies characterized by the degeneration of rod photoreceptors, followed by the degeneration of... (Review)
Review
Retinitis pigmentosa (RP) comprises a group of inherited retinal dystrophies characterized by the degeneration of rod photoreceptors, followed by the degeneration of cone photoreceptors. As a result of photoreceptor degeneration, affected individuals experience gradual loss of visual function, with primary symptoms of progressive nyctalopia, constricted visual fields and, ultimately, central vision loss. The onset, severity and clinical course of RP shows great variability and unpredictability, with most patients already experiencing some degree of visual disability in childhood. While RP is currently untreatable for the majority of patients, significant efforts have been made in the development of genetic therapies, which offer new hope for treatment for patients affected by inherited retinal dystrophies. In this exciting era of emerging gene therapies, it remains imperative to continue supporting patients with RP using all available options to manage their condition. Patients with RP experience a wide variety of physical, mental and social-emotional difficulties during their lifetime, of which some require timely intervention. This review aims to familiarize readers with clinical management options that are currently available for patients with RP.
Topics: Humans; Retinitis Pigmentosa; Retinal Cone Photoreceptor Cells; Retinal Rod Photoreceptor Cells; Night Blindness; Retinal Dystrophies
PubMed: 37108642
DOI: 10.3390/ijms24087481 -
Pflugers Archiv : European Journal of... Sep 2021
Topics: Animals; Humans; Photoreceptor Cells; Vision, Ocular; Visual Perception
PubMed: 34245377
DOI: 10.1007/s00424-021-02605-3 -
Methods in Cell Biology 2015Retina is a neurosensory tissue lining the back of the eye and is responsible for light detection and relaying the signal to the visual cortex in the brain. Mammalian...
Retina is a neurosensory tissue lining the back of the eye and is responsible for light detection and relaying the signal to the visual cortex in the brain. Mammalian retina consists of six major types of neurons (including photoreceptors; rods and cones) and one type of glial cells arranged in distinct layers. Photoreceptors are the most abundant cell types accounting for approximately 60% of all cells in the retina. Owing to their unique structure and function as ciliated neurons and their vast majority, dysfunction and degeneration of photoreceptors is associated with several inherited blindness disorders, such as retinitis pigmentosa, cone-rod degeneration, and age-related macular degeneration. Therefore, it is imperative to examine the structure and function of photoreceptors so that better understanding of the pathogenesis of associated diseases can be obtained for designing therapeutic modalities. In this chapter, we will provide detailed methods for analyzing photoreceptor function (electroretinography), structure, and biochemical analysis of sensory cilia of photoreceptors using mammalian retina as model system. These methods are widely used to assess photoreceptor development and degeneration during disease.
Topics: Animals; Cilia; Electrophysiological Phenomena; Electroretinography; Mice; Mice, Inbred C57BL; Microscopy, Electron, Transmission; Retina; Retinal Cone Photoreceptor Cells; Retinal Rod Photoreceptor Cells; Staining and Labeling
PubMed: 25837387
DOI: 10.1016/bs.mcb.2014.12.005 -
Pflugers Archiv : European Journal of... Sep 2021Retinal photoreceptors are neurons that convert dynamically changing patterns of light into electrical signals that are processed by retinal interneurons and ultimately... (Review)
Review
Retinal photoreceptors are neurons that convert dynamically changing patterns of light into electrical signals that are processed by retinal interneurons and ultimately transmitted to vision centers in the brain. They represent the essential first step in seeing without which the remainder of the visual system is rendered moot. To support this role, the major functions of photoreceptors are segregated into three main specialized compartments-the outer segment, the inner segment, and the pre-synaptic terminal. This compartmentalization is crucial for photoreceptor function-disruption leads to devastating blinding diseases for which therapies remain elusive. In this review, we examine the current understanding of the molecular and physical mechanisms underlying photoreceptor functional compartmentalization and highlight areas where significant knowledge gaps remain.
Topics: Animals; Cell Membrane; Humans; Photoreceptor Cells, Vertebrate; Presynaptic Terminals; Protein Transport; Retinal Neurons; Retinal Photoreceptor Cell Inner Segment; Retinal Photoreceptor Cell Outer Segment
PubMed: 33880652
DOI: 10.1007/s00424-021-02558-7 -
Advances in Experimental Medicine and... 2019Choroideremia (CHM) is associated with progressive degeneration of the retinal pigment epithelium (RPE), choriocapillaris (CC), and photoreceptors. As animal models of... (Review)
Review
Choroideremia (CHM) is associated with progressive degeneration of the retinal pigment epithelium (RPE), choriocapillaris (CC), and photoreceptors. As animal models of CHM are lacking, most information about cell survival has come from imaging affected patients. This chapter discusses a combination of imaging techniques, including fundus-guided microperimetry, confocal and non-confocal adaptive optics scanning laser ophthalmoscopy (AOSLO), fundus autofluorescence (FAF), and swept-source optical coherence tomography angiography (SS-OCTA) to analyze macular sensitivity, cone photoreceptor outer and inner segment structure, RPE structure, and CC perfusion, respectively. Combined imaging modalities such as those described here can provide sensitive measures of monitoring retinal structure and function in patients with CHM.
Topics: Angiography; Animals; Choroid; Choroideremia; Humans; Multimodal Imaging; Ophthalmoscopy; Photoreceptor Cells; Retinal Cone Photoreceptor Cells; Retinal Pigment Epithelium; Tomography, Optical Coherence
PubMed: 31884602
DOI: 10.1007/978-3-030-27378-1_23 -
Animal Cognition Nov 2023Light provides a widely abundant energy source and valuable sensory cue in nature. Most animals exposed to light have photoreceptor cells and in addition to eyes, there... (Review)
Review
Light provides a widely abundant energy source and valuable sensory cue in nature. Most animals exposed to light have photoreceptor cells and in addition to eyes, there are many extraocular strategies for light sensing. Here, we review how these simpler forms of detecting light can mediate rapid behavioural responses in animals. Examples of these behaviours include photophobic (light avoidance) or scotophobic (shadow) responses, photokinesis, phototaxis and wavelength discrimination. We review the cells and response mechanisms in these forms of elementary light detection, focusing on aquatic invertebrates with some protist and terrestrial examples to illustrate the general principles. Light cues can be used very efficiently by these simple photosensitive systems to effectively guide animal behaviours without investment in complex and energetically expensive visual structures.
Topics: Animals; Photoreceptor Cells; Eye; Light
PubMed: 37650997
DOI: 10.1007/s10071-023-01818-6 -
Cold Spring Harbor Perspectives in... Oct 2017Photoreceptors are sensory neurons designed to convert light stimuli into neurological responses. This process, called phototransduction, takes place in the outer... (Review)
Review
Photoreceptors are sensory neurons designed to convert light stimuli into neurological responses. This process, called phototransduction, takes place in the outer segments (OS) of rod and cone photoreceptors. OS are specialized sensory cilia, with analogous structures to those present in other nonmotile cilia. Deficient morphogenesis and/or dysfunction of photoreceptor sensory cilia (PSC) caused by mutations in a variety of photoreceptor-specific and common cilia genes can lead to inherited retinal degenerations (IRDs). IRDs can manifest as isolated retinal diseases or syndromic diseases. In this review, we describe the structure and composition of PSC and different forms of ciliopathies with retinal involvement. We review the genetics of the IRDs, which are monogenic disorders but genetically diverse with regard to causality.
Topics: Animals; Cilia; Humans; Photoreceptor Cells; Protein Transport; Retina
PubMed: 28289063
DOI: 10.1101/cshperspect.a028274 -
Developmental Biology Aug 2021Synapses in the outer retina are the first information relay points in vision. Here, photoreceptors form synapses onto two types of interneurons, bipolar cells and... (Review)
Review
Synapses in the outer retina are the first information relay points in vision. Here, photoreceptors form synapses onto two types of interneurons, bipolar cells and horizontal cells. Because outer retina synapses are particularly large and highly ordered, they have been a useful system for the discovery of mechanisms underlying synapse specificity and maintenance. Understanding these processes is critical to efforts aimed at restoring visual function through repairing or replacing neurons and promoting their connectivity. We review outer retina neuron synapse architecture, neural migration modes, and the cellular and molecular pathways that play key roles in the development and maintenance of these connections. We further discuss how these mechanisms may impact connectivity in the retina.
Topics: Animals; Humans; Interneurons; Photoreceptor Cells; Retina; Retinal Cone Photoreceptor Cells; Retinal Horizontal Cells; Synapses; Vision, Ocular
PubMed: 33848537
DOI: 10.1016/j.ydbio.2021.04.001 -
Nature Aug 2023The concomitant occurrence of tissue growth and organization is a hallmark of organismal development. This often means that proliferating and differentiating cells are...
The concomitant occurrence of tissue growth and organization is a hallmark of organismal development. This often means that proliferating and differentiating cells are found at the same time in a continuously changing tissue environment. How cells adapt to architectural changes to prevent spatial interference remains unclear. Here, to understand how cell movements that are key for growth and organization are orchestrated, we study the emergence of photoreceptor neurons that occur during the peak of retinal growth, using zebrafish, human tissue and human organoids. Quantitative imaging reveals that successful retinal morphogenesis depends on the active bidirectional translocation of photoreceptors, leading to a transient transfer of the entire cell population away from the apical proliferative zone. This pattern of migration is driven by cytoskeletal machineries that differ depending on the direction: microtubules are exclusively required for basal translocation, whereas actomyosin is involved in apical movement. Blocking the basal translocation of photoreceptors induces apical congestion, which hampers the apical divisions of progenitor cells and leads to secondary defects in lamination. Thus, photoreceptor migration is crucial to prevent competition for space, and to allow concurrent tissue growth and lamination. This shows that neuronal migration, in addition to its canonical role in cell positioning, can be involved in coordinating morphogenesis.
Topics: Animals; Humans; Actomyosin; Cell Competition; Cell Differentiation; Cell Movement; Cell Proliferation; Microtubules; Morphogenesis; Organoids; Photoreceptor Cells; Retina; Zebrafish
PubMed: 37558872
DOI: 10.1038/s41586-023-06392-y