Photosensitive afferent neurons located in the peripheral retina, with their density increases radially away from the FOVEA CENTRALIS. Being much more sensitive to light than the RETINAL CONE CELLS, the rod cells are responsible for twilight vision (at scotopic intensities) as well as peripheral vision, but provide no color discrimination.
Specialized cells that detect and transduce light. They are classified into two types based on their light reception structure, the ciliary photoreceptors and the rhabdomeric photoreceptors with MICROVILLI. Ciliary photoreceptor cells use OPSINS that activate a PHOSPHODIESTERASE phosphodiesterase cascade. Rhabdomeric photoreceptor cells use opsins that activate a PHOSPHOLIPASE C cascade.
The portion of a retinal rod cell situated between the ROD INNER SEGMENT and the RETINAL PIGMENT EPITHELIUM. It contains a stack of photosensitive disk membranes laden with RHODOPSIN.
A purplish-red, light-sensitive pigment found in RETINAL ROD CELLS of most vertebrates. It is a complex consisting of a molecule of ROD OPSIN and a molecule of 11-cis retinal (RETINALDEHYDE). Rhodopsin exhibits peak absorption wavelength at about 500 nm.
A heterotrimeric GTP-binding protein that mediates the light activation signal from photolyzed rhodopsin to cyclic GMP phosphodiesterase and is pivotal in the visual excitation process. Activation of rhodopsin on the outer membrane of rod and cone cells causes GTP to bind to transducin followed by dissociation of the alpha subunit-GTP complex from the beta/gamma subunits of transducin. The alpha subunit-GTP complex activates the cyclic GMP phosphodiesterase which catalyzes the hydrolysis of cyclic GMP to 5'-GMP. This leads to closure of the sodium and calcium channels and therefore hyperpolarization of the rod cells. EC 3.6.1.-.
Specialized PHOTOTRANSDUCTION neurons in the vertebrates, such as the RETINAL ROD CELLS and the RETINAL CONE CELLS. Non-visual photoreceptor neurons have been reported in the deep brain, the PINEAL GLAND and organs of the circadian system.
Photosensitive afferent neurons located primarily within the FOVEA CENTRALIS of the MACULA LUTEA. There are three major types of cone cells (red, blue, and green) whose photopigments have different spectral sensitivity curves. Retinal cone cells operate in daylight vision (at photopic intensities) providing color recognition and central visual acuity.
The ten-layered nervous tissue membrane of the eye. It is continuous with the OPTIC NERVE and receives images of external objects and transmits visual impulses to the brain. Its outer surface is in contact with the CHOROID and the inner surface with the VITREOUS BODY. The outer-most layer is pigmented, whereas the inner nine layers are transparent.
A retrogressive pathological change in the retina, focal or generalized, caused by genetic defects, inflammation, trauma, vascular disease, or aging. Degeneration affecting predominantly the macula lutea of the retina is MACULAR DEGENERATION. (Newell, Ophthalmology: Principles and Concepts, 7th ed, p304)
Photosensitive proteins expressed in the ROD PHOTORECEPTOR CELLS. They are the protein components of rod photoreceptor pigments such as RHODOPSIN.
That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.
Specialized cells in the invertebrates that detect and transduce light. They are predominantly rhabdomeric with an array of photosensitive microvilli. Illumination depolarizes invertebrate photoreceptors by stimulating Na+ influx across the plasma membrane.
A 48-Kd protein of the outer segment of the retinal rods and a component of the phototransduction cascade. Arrestin quenches G-protein activation by binding to phosphorylated photolyzed rhodopsin. Arrestin causes experimental autoimmune uveitis when injected into laboratory animals.
A PROTEIN-SERINE-THREONINE KINASE that is found in PHOTORECEPTOR CELLS. It mediates light-dependent PHOSPHORYLATION of RHODOPSIN and plays an important role in PHOTOTRANSDUCTION.
Enzymes that catalyze the hydrolysis of cyclic GMP to yield guanosine-5'-phosphate.
Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.
The process in which light signals are transformed by the PHOTORECEPTOR CELLS into electrical signals which can then be transmitted to the brain.
Recording of electric potentials in the retina after stimulation by light.
Photosensitive protein complexes of varied light absorption properties which are expressed in the PHOTORECEPTOR CELLS. They are OPSINS conjugated with VITAMIN A-based chromophores. Chromophores capture photons of light, leading to the activation of opsins and a biochemical cascade that ultimately excites the photoreceptor cells.
A cyclic nucleotide phosphodiesterase subfamily that is highly specific for CYCLIC GMP. It is found predominantly in the outer segment PHOTORECEPTOR CELLS of the RETINA. It is comprised of two catalytic subunits, referred to as alpha and beta, that form a dimer. In addition two regulatory subunits, referred to as gamma and delta, modulate the activity and localization of the enzyme.
Adjustment of the eyes under conditions of low light. The sensitivity of the eye to light is increased during dark adaptation.
A genus of the Ambystomatidae family. The best known species are the axolotl AMBYSTOMA MEXICANUM and the closely related tiger salamander Ambystoma tigrinum. They may retain gills and remain aquatic without developing all of the adult characteristics. However, under proper changes in the environment they metamorphose.
A neuronal calcium-sensor protein that is found in ROD PHOTORECEPTORS and CONE PHOTORECEPTORS. It interacts with G-PROTEIN-COUPLED RECEPTOR KINASE 1 in a Ca2+ dependent manner and plays an important role in PHOTOTRANSDUCTION.
Hereditary, progressive degeneration of the neuroepithelium of the retina characterized by night blindness and progressive contraction of the visual field.
The conversion of absorbed light energy into molecular signals.
A species of the true toads, Bufonidae, becoming fairly common in the southern United States and almost pantropical. The secretions from the skin glands of this species are very toxic to animals.
Guanosine cyclic 3',5'-(hydrogen phosphate). A guanine nucleotide containing one phosphate group which is esterified to the sugar moiety in both the 3'- and 5'-positions. It is a cellular regulatory agent and has been described as a second messenger. Its levels increase in response to a variety of hormones, including acetylcholine, insulin, and oxytocin and it has been found to activate specific protein kinases. (From Merck Index, 11th ed)
INTERNEURONS of the vertebrate RETINA containing two processes. They receive inputs from the RETINAL PHOTORECEPTOR CELLS and send outputs to the RETINAL GANGLION CELLS. The bipolar cells also make lateral connections in the retina with the RETINAL HORIZONTAL CELLS and with the AMACRINE CELLS.
The absence of light.
A subgroup of cyclic nucleotide-regulated ION CHANNELS within the superfamily of pore-loop cation channels. They are expressed in OLFACTORY NERVE cilia and in PHOTORECEPTOR CELLS and some PLANTS.
Constriction of the pupil in response to light stimulation of the retina. It refers also to any reflex involving the iris, with resultant alteration of the diameter of the pupil. (Cline et al., Dictionary of Visual Science, 4th ed)
Neurons of the innermost layer of the retina, the internal plexiform layer. They are of variable sizes and shapes, and their axons project via the OPTIC NERVE to the brain. A small subset of these cells act as photoreceptors with projections to the SUPRACHIASMATIC NUCLEUS, the center for regulating CIRCADIAN RHYTHM.
Works containing information articles on subjects in every field of knowledge, usually arranged in alphabetical order, or a similar work limited to a special field or subject. (From The ALA Glossary of Library and Information Science, 1983)
Component of the NATIONAL INSTITUTES OF HEALTH. It conducts and supports research on the causes, diagnosis, and treatment of diseases of the eye and visual system. It was originally part of the National Institute of Neurological Diseases and Blindness. The National Eye Institute was established in 1968.
The application of discoveries generated by laboratory research and preclinical studies to the development of clinical trials and studies in humans. A second area of translational research concerns enhancing the adoption of best practices.
A quality-of-life scale developed in the United States in 1972 as a measure of health status or dysfunction generated by a disease. It is a behaviorally based questionnaire for patients and addresses activities such as sleep and rest, mobility, recreation, home management, emotional behavior, social interaction, and the like. It measures the patient's perceived health status and is sensitive enough to detect changes or differences in health status occurring over time or between groups. (From Medical Care, vol.xix, no.8, August 1981, p.787-805)
Time period from 1801 through 1900 of the common era.
Time period from 1901 through 2000 of the common era.
Clarity or sharpness of OCULAR VISION or the ability of the eye to see fine details. Visual acuity depends on the functions of RETINA, neuronal transmission, and the interpretative ability of the brain. Normal visual acuity is expressed as 20/20 indicating that one can see at 20 feet what should normally be seen at that distance. Visual acuity can also be influenced by brightness, color, and contrast.
A surgical specialty concerned with the structure and function of the eye and the medical and surgical treatment of its defects and diseases.
DNA sequences which are recognized (directly or indirectly) and bound by a DNA-dependent RNA polymerase during the initiation of transcription. Highly conserved sequences within the promoter include the Pribnow box in bacteria and the TATA BOX in eukaryotes.
Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.
Devices which are very resistant to wear and may be used over a long period of time. They include items such as wheelchairs, hospital beds, artificial limbs, etc.
Pricing statements presented by more than one party for the purpose of securing a contract.
Prosthetic replacements for arms, legs, and parts thereof.
Artificial substitutes for body parts, and materials inserted into tissue for functional, cosmetic, or therapeutic purposes. Prostheses can be functional, as in the case of artificial arms and legs, or cosmetic, as in the case of an artificial eye. Implants, all surgically inserted or grafted into the body, tend to be used therapeutically. IMPLANTS, EXPERIMENTAL is available for those used experimentally.
Concept referring to the standardized fees for services rendered by health care providers, e.g., laboratories and physicians, and reimbursement for those services under Medicare Part B. It includes acceptance by the physician.
Methods and techniques used to modify or select cells and develop conditions for growing cells for biosynthetic production of molecules (METABOLIC ENGINEERING), for generation of tissue structures and organs in vitro (TISSUE ENGINEERING), or for other BIOENGINEERING research objectives.