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Medecine Sciences : M/S 2020The neuroretina is a functional unit of the central nervous system that converts a light signal into a nerve impulse. Of neuroectodermal origin, derived from the... (Review)
Review
The neuroretina is a functional unit of the central nervous system that converts a light signal into a nerve impulse. Of neuroectodermal origin, derived from the diencephalon, the neuroretina is a layered tissue composed of six types of neuronal cells (two types of photoreceptors: cones and rods, horizontal, bipolar, amacrine and ganglion cells) and three types of glial cells (Müller glial cells, astrocytes and microglial cells). The neuroretina lays on the retinal pigmentary epithelium, that together form the retina. The existence of the internal and external blood-retinal barriers and intra-retinal junctions reflects the fineness of regulation of the retinal exchanges with the circulation and within the retina itself. The central zone of the human retina, which is highly specialized for visual acuity, has anatomical specificities. Recent imaging methods make it possible now to enrich our knowledge of the anatomical and functional characteristics of the retina, which are still imperfectly described.
Topics: Animals; Choroid; Humans; Neuroglia; Retina; Retinal Cone Photoreceptor Cells; Retinal Pigment Epithelium; Retinal Rod Photoreceptor Cells; Retinal Vessels
PubMed: 32614310
DOI: 10.1051/medsci/2020094 -
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 -
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 -
Medecine Sciences : M/S Mar 2017The retina is a light-sensitive tissue in the vertebrate eye that detects and processes visual images. The eye, including retina, is exposed to a variety of... (Review)
Review
The retina is a light-sensitive tissue in the vertebrate eye that detects and processes visual images. The eye, including retina, is exposed to a variety of environmental insults and stressors, among which genetic mutations and age-associated alterations that impair their function. Autophagy is a catabolic pathway that promotes the degradation and recycling of cellular components under basal and stress conditions. Proteins, lipids, and even whole organelles are engulfed in autophagosomes and delivered to the lysosome for elimination. Research has only begun to examine the role of autophagy in the visual system. Here, we review the main studies that have sought to explain autophagy's importance for visual function.
Topics: Animals; Autophagy; Humans; Photoreceptor Cells, Vertebrate; Retina; Retinal Pigment Epithelium; Vision, Ocular
PubMed: 28367817
DOI: 10.1051/medsci/20173303017 -
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