Adjustment of the eyes under conditions of low light. The sensitivity of the eye to light is increased during dark adaptation.
The adjustment of the eye to variations in the intensity of light. Light adaptation is the adjustment of the eye when the light threshold is increased; DARK ADAPTATION when the light is greatly reduced. (From Cline et al., Dictionary of Visual Science, 4th ed)
The non-genetic biological changes of an organism in response to challenges in its ENVIRONMENT.
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.
Recording of electric potentials in the retina after stimulation by light.
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.
The absence of light.
Failure or imperfection of vision at night or in dim light, with good vision only on bright days. (Dorland, 27th ed)
That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.
A genus of zygomycetous fungi in the family Mucoraceae, order MUCORALES, forming mycelia having a metallic sheen. It has been used for research on phototropism.
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.
Function of the human eye that is used in dim illumination (scotopic intensities) or at nighttime. Scotopic vision is performed by RETINAL ROD PHOTORECEPTORS with high sensitivity to light and peak absorption wavelength at 507 nm near the blue end of the spectrum.
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.
The minimum amount of stimulus energy necessary to elicit a sensory response.
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.
The process in which light signals are transformed by the PHOTORECEPTOR CELLS into electrical signals which can then be transmitted to the brain.
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.
A nutritional condition produced by a deficiency of VITAMIN A in the diet, characterized by NIGHT BLINDNESS and other ocular manifestations such as dryness of the conjunctiva and later of the cornea (XEROPHTHALMIA). Vitamin A deficiency is a very common problem worldwide, particularly in developing countries as a consequence of famine or shortages of vitamin A-rich foods. In the United States it is found among the urban poor, the elderly, alcoholics, and patients with malabsorption. (From Cecil Textbook of Medicine, 19th ed, p1179)
A carotenoid constituent of visual pigments. It is the oxidized form of retinol which functions as the active component of the visual cycle. It is bound to the protein opsin forming the complex rhodopsin. When stimulated by visible light, the retinal component of the rhodopsin complex undergoes isomerization at the 11-position of the double bond to the cis-form; this is reversed in "dark" reactions to return to the native trans-configuration.
Investigative technique commonly used during ELECTROENCEPHALOGRAPHY in which a series of bright light flashes or visual patterns are used to elicit brain activity.
A group of methane-based halogenated hydrocarbons containing one or more fluorine and chlorine atoms.
A vacuum tube equipped with an electron emitting CATHODE and a fluorescent screen which emits visible light when excited by the cathode ray. Cathode ray tubes are used as imaging devises for TELEVISIONS; COMPUTER TERMINALS; TEXT TELECOMMUNICATION DEVICES; oscilloscopes; and other DATA DISPLAY devices.
Retinol and derivatives of retinol that play an essential role in metabolic functioning of the retina, the growth of and differentiation of epithelial tissue, the growth of bone, reproduction, and the immune response. Dietary vitamin A is derived from a variety of CAROTENOIDS found in plants. It is enriched in the liver, egg yolks, and the fat component of dairy products.
The point or frequency at which all flicker of an intermittent light stimulus disappears.
Processes and properties of the EYE as a whole or of any of its parts.
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.
Changes in biological features that help an organism cope with its ENVIRONMENT. These changes include physiological (ADAPTATION, PHYSIOLOGICAL), phenotypic and genetic changes.
A group of tetraterpenes, with four terpene units joined head-to-tail. Biologically active members of this class are used clinically in the treatment of severe cystic ACNE; PSORIASIS; and other disorders of keratinization.
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)
The concave interior of the eye, consisting of the retina, the choroid, the sclera, the optic disk, and blood vessels, seen by means of the ophthalmoscope. (Cline et al., Dictionary of Visual Science, 4th ed)
Hereditary, progressive degeneration of the neuroepithelium of the retina characterized by night blindness and progressive contraction of the visual field.
An order of the Amphibia class which includes salamanders and newts. They are characterized by usually having slim bodies and tails, four limbs of about equal size (except in Sirenidae), and a reduction in skull bones.
The conversion of absorbed light energy into molecular signals.
Defects of color vision are mainly hereditary traits but can be secondary to acquired or developmental abnormalities in the CONES (RETINA). Severity of hereditary defects of color vision depends on the degree of mutation of the ROD OPSINS genes (on X CHROMOSOME and CHROMOSOME 3) that code the photopigments for red, green and blue.
A mobile, very volatile, highly flammable liquid used as an inhalation anesthetic and as a solvent for waxes, fats, oils, perfumes, alkaloids, and gums. It is mildly irritating to skin and mucous membranes.
Diseases in any part of the GASTROINTESTINAL TRACT or the accessory organs (LIVER; BILIARY TRACT; PANCREAS).
Photosensitive proteins expressed in the ROD PHOTORECEPTOR CELLS. They are the protein components of rod photoreceptor pigments such as RHODOPSIN.
Photosensitive proteins in the membranes of PHOTORECEPTOR CELLS such as the rods and the cones. Opsins have varied light absorption properties and are members of the G-PROTEIN-COUPLED RECEPTORS family. Their ligands are VITAMIN A-based chromophores.
The study of the physiological basis of human and animal behavior.
Mental processing of chromatic signals (COLOR VISION) from the eye by the VISUAL CORTEX where they are converted into symbolic representations. Color perception involves numerous neurons, and is influenced not only by the distribution of wavelengths from the viewed object, but also by its background color and brightness contrast at its boundary.
Type of vision test used to determine COLOR VISION DEFECTS.
Enzymes that catalyze the rearrangement of geometry about double bonds. EC 5.2.
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.
Elements of limited time intervals, contributing to particular results or situations.
Degenerative changes in the RETINA usually of older adults which results in a loss of vision in the center of the visual field (the MACULA LUTEA) because of damage to the retina. It occurs in dry and wet forms.
Rhodopsins found in the PURPLE MEMBRANE of halophilic archaea such as HALOBACTERIUM HALOBIUM. Bacteriorhodopsins function as an energy transducers, converting light energy into electrochemical energy via PROTON PUMPS.
The aperture in the iris through which light passes.
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.
I'm sorry for any confusion, but "Nepal" is not a medical term that has a definition in the field of medicine. It is actually the name of a country located in South Asia, known officially as the Federal Democratic Republic of Nepal. If you have any questions related to medicine or health, I would be happy to try and help answer those for you!
An area approximately 1.5 millimeters in diameter within the macula lutea where the retina thins out greatly because of the oblique shifting of all layers except the pigment epithelium layer. It includes the sloping walls of the fovea (clivus) and contains a few rods in its periphery. In its center (foveola) are the cones most adapted to yield high visual acuity, each cone being connected to only one ganglion cell. (Cline et al., Dictionary of Visual Science, 4th ed)
The ability to detect sharp boundaries (stimuli) and to detect slight changes in luminance at regions without distinct contours. Psychophysical measurements of this visual function are used to evaluate visual acuity and to detect eye disease.
Measurement of the various properties of light.
The inner layer of CHOROID, also called the lamina basalis choroideae, located adjacent to the RETINAL PIGMENT EPITHELIUM; (RPE) of the EYE. It is a membrane composed of the basement membranes of the choriocapillaris ENDOTHELIUM and that of the RPE. The membrane stops at the OPTIC NERVE, as does the RPE.
Recording of the average amplitude of the resting potential arising between the cornea and the retina in light and dark adaptation as the eyes turn a standard distance to the right and the left. The increase in potential with light adaptation is used to evaluate the condition of the retinal pigment epithelium.
Retinal diseases refer to a diverse group of vision-threatening disorders that affect the retina's structure and function, including age-related macular degeneration, diabetic retinopathy, retinal detachment, retinitis pigmentosa, and macular edema, among others.
The rate dynamics in chemical or physical systems.
The layer of pigment-containing epithelial cells in the RETINA; the CILIARY BODY; and the IRIS in the eye.
A kingdom of eukaryotic, heterotrophic organisms that live parasitically as saprobes, including MUSHROOMS; YEASTS; smuts, molds, etc. They reproduce either sexually or asexually, and have life cycles that range from simple to complex. Filamentous fungi, commonly known as molds, refer to those that grow as multicellular colonies.
The selecting and organizing of visual stimuli based on the individual's past experience.
Photochemistry is the study of chemical reactions induced by absorption of light, resulting in the promotion of electrons to higher energy levels and subsequent formation of radicals or excited molecules that can undergo various reaction pathways.
Visual impairments limiting one or more of the basic functions of the eye: visual acuity, dark adaptation, color vision, or peripheral vision. These may result from EYE DISEASES; OPTIC NERVE DISEASES; VISUAL PATHWAY diseases; OCCIPITAL LOBE diseases; OCULAR MOTILITY DISORDERS; and other conditions (From Newell, Ophthalmology: Principles and Concepts, 7th ed, p132).
The total area or space visible in a person's peripheral vision with the eye looking straightforward.
Method of measuring and mapping the scope of vision, from central to peripheral of each eye.
The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)
'Eye proteins' are structural or functional proteins, such as crystallins, opsins, and collagens, located in various parts of the eye, including the cornea, lens, retina, and aqueous humor, that contribute to maintaining transparency, refractive power, phototransduction, and overall integrity of the visual system.
The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.

The neuronal basis of a sensory analyser, the acridid movement detector system. I. Effects of simple incremental and decremental stimuli in light and dark adapted animals. (1/1146)

1. The response of the movement detector (MD) system to proportionally constant incremental and decremental stimuli has been studied at various degrees of light and dark adaptation. Action potentials in the descending contralateral movement detector neurone were taken as the indicator of response. 2. Over a range of at least six log10 units of adapting luminance, the MD system behaves as an ON/OFF unit, giving responses to both incremental and decremental changes in the illumination of a 5 degrees target. 3. With increasing amplitudes of stimuli, both the ON and OFF responses saturate rapidly. Saturation is reached sooner at higher levels of light adaptation. At all levels of light adaptation, the OFF response is greater than the ON. The ratio for saturating stimuli is approximately constant at around 3:2. 4. At the brightest adapting luminances used (20 000 cd/m2) the ON response is reduced but not lost. At the lowest (0-004 cd/m2) the OFF response to a 5 degrees disc fails, but can be regained by increasing the test area to 10 degrees. 5. From what is known of the retina of locusts and other insects, it is thought that light and dark adaptation in the MD system can be adequately explained by events at the retinula cell.  (+info)

Occupancy of the chromophore binding site of opsin activates visual transduction in rod photoreceptors. (2/1146)

The retinal analogue beta-ionone was used to investigate possible physiological effects of the noncovalent interaction between rod opsin and its chromophore 11-cis retinal. Isolated salamander rod photoreceptors were exposed to bright light that bleached a significant fraction of their pigment, were allowed to recover to a steady state, and then were exposed to beta-ionone. Our experiments show that in bleach-adapted rods beta-ionone causes a decrease in light sensitivity and dark current and an acceleration of the dim flash photoresponse and the rate constants of guanylyl cyclase and cGMP phosphodiesterase. Together, these observations indicate that in bleach-adapted rods beta-ionone activates phototransduction in the dark. Control experiments showed no effect of beta-ionone in either fully dark-adapted or background light-adapted cells, indicating direct interaction of beta-ionone with the free opsin produced by bleaching. We speculate that beta-ionone binds specifically in the chromophore pocket of opsin to produce a complex that is more catalytically potent than free opsin alone. We hypothesize that a similar reaction may occur in the intact retina during pigment regeneration. We propose a model of rod pigment regeneration in which binding of 11-cis retinal to opsin leads to activation of the complex accompanied by a decrease in light sensitivity. The subsequent covalent attachment of retinal to opsin completely inactivates opsin and leads to the recovery of sensitivity. Our findings resolve the conflict between biochemical and physiological data concerning the effect of the occupancy of the chromophore binding site on the catalytic potency of opsin. We show that binding of beta-ionone to rod opsin produces effects opposite to its previously described effects on cone opsin. We propose that this distinction is due to a fundamental difference in the interaction of rod and cone opsins with retinal, which may have implications for the different physiology of the two types of photoreceptors.  (+info)

Hypersensitivity in the anterior median eye of a jumping spider. (3/1146)

Changes in sensitivity of the photoreceptor cells of the anterior median eye of the jumping spider Menemerus confusus Boes. et Str. have been studied by recording electroretinograms (ERGs) and receptor potentials. The amplitudes of the responses (ERGs and receptor potentials) increase during repetitive stimulation, with a maximum increase at 3-5 s intervals. The sensitivity of the photoreceptor cell is greater for about 60 s following illumination (maximum magnitude at 3-5 s) than it is during complete dark adaptation. This phenomenon, which we call 'hypersensitivity', is lost within one day following surgery in physiological saline. Upon loss of hypersensitivity, the sensitivity decrease during light adaptation is greater than for the normal eye and the small increase of sensitivity following the onset of illumination observed for the normal eye is lost.  (+info)

Retinoid kinetics in eye tissues of VPP transgenic mice and their normal littermates. (4/1146)

PURPOSE: VPP mice, which possess a mutant transgene for opsin (V20G, P23H, P27L), exhibit a progressive rod degeneration that resembles one form of human autosomal dominant retinitis pigmentosa. In the present study the association of the development of VPP rod degeneration with abnormal operation of the retinoid visual cycle was examined. METHODS: Dark-adapted VPP mice and normal littermates were anesthetized and the pupils dilated. One eye of each animal was illuminated for 2 minutes; the other eye was shielded from the light and served as a control. Each animal was then dark adapted for a defined period (0-300 minutes) and killed. Retinoids contained in the retina, retinal pigment epithelium (RPE), and extracellular medium were recovered by means of formaldehyde-, isopropanol- and ethanol-based extractions and analyzed by high-performance liquid chromatography. RESULTS: Total amounts of retinoid recovered from unilluminated eyes of 2-month-old normal and VPP mice were 425 +/- 90 picomoles per eye and 115 +/- 33 picomoles per eye, respectively (mean +/- SD). Relative distributions of retinoids within normal and VPP eyes were similar. In normal and VPP animals, illumination for 2 minutes produced a similar immediate reduction in the molar percent of total retinoid represented by 11-cis retinal in the retina (average reduction of 34% and 28% in normal and VPP animals, respectively) and a similar transient increase of all-trans retinal in the retina. In both groups the decline of all-trans retinal was accompanied by an increase in total retinyl ester. In normal and VPP animals, a period of approximately 40 minutes or more preceded initiation of the recovery of 11-cis retinal in the retina, and the time course of this recovery was generally similar to that for the decline of retinyl ester. The overall dark-adaptation period required for half-completion of 11-cis retinal recovery was approximately 150 minutes. In neither group did illumination produce a substantial peak of all-trans retinol in the retina. CONCLUSIONS: The evident approximately fourfold reduction of total retinoid in the eyes of 2-month-old VPP mice is consistent with histologic and electroretinographic abnormalities determined in previous studies. Despite this marked abnormality in retinoid content, retinoid cycling in the VPP is remarkably similar to that in normal littermates. The data place constraints on the functional consequences of any abnormality in retinoid processing that may be present at this stage of the VPP rod degeneration.  (+info)

Ocular signs and symptoms and vitamin A status in patients with cystic fibrosis treated with daily vitamin A supplements. (5/1146)

BACKGROUND/AIMS: Patients with cystic fibrosis (CF) may have low plasma vitamin A levels from malabsorption, zinc deficiency, liver disease, or poor compliance with prescribed supplements. In view of the increasing number of adults with CF, many of whom drive cars, it is important to assess vitamin A status. In our centre an attempt has been made to achieve normal levels of fat soluble vitamins by annual estimation of plasma levels and appropriate oral supplementation. This study aimed to determine if this approach prevents vitamin A deficiency and the consequent problems with dark adaptation. METHODS: The study was conducted at the regional adult and paediatric cystic fibrosis unit and the patients were recruited from there. Dark adaptation studies were conducted at the department of ophthalmology, St James's University Hospital. All patients are regularly seen in the outpatient department by a CF specialist dietitian and have a comprehensive annual dietary assessment. 28 patients had the following investigations: serum retinol, plasma zinc, serum retinol binding protein, liver function tests, dark adaptation, contrast sensitivity, and anterior ocular surface status. 25 age and sex matched controls without CF or ocular pathology were also recruited for the dark adaptation study. RESULTS: None of the patients had vitamin A deficiency, the median value of serum retinol being 48 microg/dl, range 31-80 microg/dl (normal range 30-80 microg/dl). Dark adaptation was normal in all cases compared with the control group where the mean value was 3.4 log units of threshold luminance (95% confidence interval 2.4-4.0). None of the test group had a value of threshold luminance 2 SD above the mean value for the control group. Eight patients had reduced contrast sensitivity. The median value for serum zinc was 14.2 micromol/ l, range 13-81 micromol/l (normal range 8-23 micromol/l) and the median value for retinol binding protein was 36 mg/l, range 13-81 mg/l (normal range 35-58 mg/l). There was no correlation between dark adaptation and serum retinol, zinc, or retinol binding protein. Two patients had clinical evidence of dry eye. CONCLUSION: Regular estimates of plasma vitamin A together with appropriate supplementation and expert dietetic review can maintain normal dark adaptation in patients with cystic fibrosis. The occurrence of reduced contrast sensitivity function is well documented but remains an unexplained phenomenon and deserves further study.  (+info)

Testing optimum viewing conditions for mammographic image displays. (6/1146)

The viewbox luminance and viewing room light level are important parameters in a medical film display, but these parameters have not had much attention. Spatial variations and too much room illumination can mask real signal or create the false perception of a signal. This presentation looks at how scotopic light sources and dark-adapted radiologists may identify more real diseases.  (+info)

Effects of inhibiting glutamine synthetase and blocking glutamate uptake on b-wave generation in the isolated rat retina. (7/1146)

The purpose of the present experiments was to evaluate the contribution of the glutamate-glutamine cycle in retinal glial (Muller) cells to photoreceptor cell synaptic transmission. Dark-adapted isolated rat retinas were superfused with oxygenated bicarbonate-buffered media. Recordings were made of the b-wave of the electroretinogram as a measure of light-induced photoreceptor to ON-bipolar neuron transmission. L-methionine sulfoximine (1-10 mM) was added to superfusion media to inhibit glutamine synthetase, a Muller cell specific enzyme, by more than 99% within 5-10 min, thereby disrupting the conversion of glutamate to glutamine in the Muller cells. Threo-hydroxyaspartic acid and D-aspartate were used to block glutamate transporters. The amplitude of the b-wave was well maintained for 1-2 h provided 0.25 mM glutamate or 0.25 mM glutamine was included in the media. Without exogenous glutamate or glutamine the amplitude of the b-wave declined by about 70% within 1 h. Inhibition of glutamate transporters led to a rapid (2-5 min) reversible loss of the b-wave in the presence and absence of the amino acids. In contrast, inhibition of glutamine synthetase did not alter significantly either the amplitude of the b-wave in the presence of glutamate or glutamine or the rate of decline of the b-wave found in the absence of these amino acids. Excellent recovery of the b-wave was found when 0.25 mM glutamate was resupplied to L-methionine sulfoximine-treated retinas. The results suggest that in the isolated rat retina uptake of released glutamate into photoreceptors plays a more important role in transmitter recycling than does uptake of glutamate into Muller cells and its subsequent conversion to glutamine.  (+info)

Light adaptation and dark adaptation of human rod photoreceptors measured from the a-wave of the electroretinogram. (8/1146)

1. We recorded the a-wave of the human electroretinogram from subjects with normal vision, using a corneal electrode and ganzfeld (full-field) light stimulation. From analysis of the rising phase of rod-isolated flash responses we determined the maximum size (amax) of the a-wave, a measure of the massed circulating current of the rods, and the amplification constant (A) of transduction within the rod photoreceptors. 2. During light adaptation by steady backgrounds the maximal response was reduced, as reported previously. amax declined approximately as I0/(I0 + IB), where IB is retinal illuminance and I0 is a constant. In different subjects I0 ranged from 40 to 100 trolands, with a mean of 70 trolands, corresponding to about 600 photoisomerizations s-1 per rod. (1 troland is the retinal illuminance that results when a surface luminance of 1 cd m-2 is viewed through a pupil area of 1 mm2.) The amplification constant A decreased only slightly in the presence of steady backgrounds. 3. Following a full bleach amax recovered along an S-shaped curve over a period of 30 min. There was no detectable response for the first 5 min, and half-maximal recovery took 13-17 min. 4. The apparent amplification constant decreased at early times after large bleaches. However, upon correction for reduced light absorption due to loss of pigment, with regeneration of rhodopsin occurring with a time constant of 9-15 min in different subjects, it appeared that the true value of A was probably unchanged by bleaching. 5. The recovery of amax following a bleach could be converted into recovery of equivalent background intensity, using a 'Crawford transformation' derived from the light adaptation results. Following bleaches ranging from 10 to > 99 %, the equivalent background intensity decayed approximately exponentially, with a time constant of about 3 min. 6. The time taken for amax to recover to a fixed proportion of its original level increased approximately linearly (rather than logarithmically) with fractional bleach, with a slope of about 12 min per 100 % bleach. Similar behaviour has previously been seen in psychophysical dark adaptation experiments, for the dependence of the 'second component' of recovery on the level of bleaching.  (+info)

Dark adaptation is the process by which the eyes adjust to low levels of light. This process allows the eyes to become more sensitive to light and see better in the dark. It involves the dilation of the pupils, as well as chemical changes in the rods and cones (photoreceptor cells) of the retina. These changes allow the eye to detect even small amounts of light and improve visual acuity in low-light conditions. Dark adaptation typically takes several minutes to occur fully, but can be faster or slower depending on various factors such as age, prior exposure to light, and certain medical conditions. It is an important process for maintaining good vision in a variety of lighting conditions.

Ocular adaptation is the ability of the eye to adjust and accommodate to changes in visual input and lighting conditions. This process allows the eye to maintain a clear and focused image over a range of different environments and light levels. There are several types of ocular adaptation, including:

1. Light Adaptation: This refers to the eye's ability to adjust to different levels of illumination. When moving from a dark environment to a bright one, the pupils constrict to let in less light, and the sensitivity of the retina decreases. Conversely, when moving from a bright environment to a dark one, the pupils dilate to let in more light, and the sensitivity of the retina increases.
2. Dark Adaptation: This is the process by which the eye adjusts to low light conditions. It involves the dilation of the pupils and an increase in the sensitivity of the rods (specialised cells in the retina that are responsible for vision in low light conditions). Dark adaptation can take several minutes to occur fully.
3. Color Adaptation: This refers to the eye's ability to adjust to changes in the color temperature of light sources. For example, when moving from a room lit by incandescent light to one lit by fluorescent light, the eye may need to adjust its perception of colors to maintain accurate color vision.
4. Accommodation: This is the process by which the eye changes focus from distant to near objects. The lens of the eye changes shape to bend the light rays entering the eye and bring them into sharp focus on the retina.

Overall, ocular adaptation is an essential function that allows us to see clearly and accurately in a wide range of environments and lighting conditions.

Physiological adaptation refers to the changes or modifications that occur in an organism's biological functions or structures as a result of environmental pressures or changes. These adaptations enable the organism to survive and reproduce more successfully in its environment. They can be short-term, such as the constriction of blood vessels in response to cold temperatures, or long-term, such as the evolution of longer limbs in animals that live in open environments.

In the context of human physiology, examples of physiological adaptation include:

1. Acclimatization: The process by which the body adjusts to changes in environmental conditions, such as altitude or temperature. For example, when a person moves to a high-altitude location, their body may produce more red blood cells to compensate for the lower oxygen levels, leading to improved oxygen delivery to tissues.

2. Exercise adaptation: Regular physical activity can lead to various physiological adaptations, such as increased muscle strength and endurance, enhanced cardiovascular function, and improved insulin sensitivity.

3. Hormonal adaptation: The body can adjust hormone levels in response to changes in the environment or internal conditions. For instance, during prolonged fasting, the body releases stress hormones like cortisol and adrenaline to help maintain energy levels and prevent muscle wasting.

4. Sensory adaptation: Our senses can adapt to different stimuli over time. For example, when we enter a dark room after being in bright sunlight, it takes some time for our eyes to adjust to the new light level. This process is known as dark adaptation.

5. Aging-related adaptations: As we age, various physiological changes occur that help us adapt to the changing environment and maintain homeostasis. These include changes in body composition, immune function, and cognitive abilities.

Photoreceptor cells are specialized neurons in the retina of the eye that convert light into electrical signals. These cells consist of two types: rods and cones. Rods are responsible for vision at low light levels and provide black-and-white, peripheral, and motion sensitivity. Cones are active at higher light levels and are capable of color discrimination and fine detail vision. Both types of photoreceptor cells contain light-sensitive pigments that undergo chemical changes when exposed to light, triggering a series of electrical signals that ultimately reach the brain and contribute to visual perception.

Electroretinography (ERG) is a medical test used to evaluate the functioning of the retina, which is the light-sensitive tissue located at the back of the eye. The test measures the electrical responses of the retina to light stimulation.

During the procedure, a special contact lens or electrode is placed on the surface of the eye to record the electrical activity generated by the retina's light-sensitive cells (rods and cones) and other cells in the retina. The test typically involves presenting different levels of flashes of light to the eye while the electrical responses are recorded.

The resulting ERG waveform provides information about the overall health and function of the retina, including the condition of the photoreceptors, the integrity of the inner retinal layers, and the health of the retinal ganglion cells. This test is often used to diagnose and monitor various retinal disorders, such as retinitis pigmentosa, macular degeneration, and diabetic retinopathy.

Retinal rod photoreceptor cells are specialized neurons in the retina of the eye that are primarily responsible for vision in low light conditions. They contain a light-sensitive pigment called rhodopsin, which undergoes a chemical change when struck by a single photon of light. This triggers a cascade of biochemical reactions that ultimately leads to the generation of electrical signals, which are then transmitted to the brain via the optic nerve.

Rod cells do not provide color vision or fine detail, but they allow us to detect motion and see in dim light. They are more sensitive to light than cone cells, which are responsible for color vision and detailed sight in bright light conditions. Rod cells are concentrated at the outer edges of the retina, forming a crescent-shaped region called the peripheral retina, with fewer rod cells located in the central region of the retina known as the fovea.

I am not aware of a medical definition for the term "darkness." In general, darkness refers to the absence of light. It is not a term that is commonly used in the medical field, and it does not have a specific clinical meaning. If you have a question about a specific medical term or concept, I would be happy to try to help you understand it.

Night blindness, also known as nyctalopia, is a visual impairment characterized by the inability to see well in low light or darkness. It's not an eye condition itself but rather a symptom of various underlying eye disorders, most commonly vitamin A deficiency and retinal diseases like retinitis pigmentosa.

In a healthy eye, a molecule called rhodopsin is present in the rods (special light-sensitive cells in our eyes responsible for vision in low light conditions). This rhodopsin requires sufficient amounts of vitamin A to function properly. When there's a deficiency of vitamin A or damage to the rods, the ability to see in dim light gets affected, leading to night blindness.

People with night blindness often have difficulty adjusting to changes in light levels, such as when entering a dark room from bright sunlight. They may also experience trouble seeing stars at night, driving at dusk or dawn, and navigating in poorly lit areas. If you suspect night blindness, it's essential to consult an eye care professional for proper diagnosis and treatment of the underlying cause.

In the context of medical terminology, "light" doesn't have a specific or standardized definition on its own. However, it can be used in various medical terms and phrases. For example, it could refer to:

1. Visible light: The range of electromagnetic radiation that can be detected by the human eye, typically between wavelengths of 400-700 nanometers. This is relevant in fields such as ophthalmology and optometry.
2. Therapeutic use of light: In some therapies, light is used to treat certain conditions. An example is phototherapy, which uses various wavelengths of ultraviolet (UV) or visible light for conditions like newborn jaundice, skin disorders, or seasonal affective disorder.
3. Light anesthesia: A state of reduced consciousness in which the patient remains responsive to verbal commands and physical stimulation. This is different from general anesthesia where the patient is completely unconscious.
4. Pain relief using light: Certain devices like transcutaneous electrical nerve stimulation (TENS) units have a 'light' setting, indicating lower intensity or frequency of electrical impulses used for pain management.

Without more context, it's hard to provide a precise medical definition of 'light'.

"Phycomyces" is not a medical term, but a genus name in the fungal kingdom, specifically within the division Mucoromycota. It belongs to the family Physalacriaceae and includes various species of saprophytic fungi that are commonly found in soil and decaying organic matter. They are known for producing large, quickly growing sporangiophores and sporangia.

In a medical context, certain fungal infections can be caused by related molds in the same division (Mucoromycota), but "Phycomyces" itself is not typically associated with human diseases.

The retina is the innermost, light-sensitive layer of tissue in the eye of many vertebrates and some cephalopods. It receives light that has been focused by the cornea and lens, converts it into neural signals, and sends these to the brain via the optic nerve. The retina contains several types of photoreceptor cells including rods (which handle vision in low light) and cones (which are active in bright light and are capable of color vision).

In medical terms, any pathological changes or diseases affecting the retinal structure and function can lead to visual impairment or blindness. Examples include age-related macular degeneration, diabetic retinopathy, retinal detachment, and retinitis pigmentosa among others.

Night vision refers to the ability to see in low light conditions, typically during night time. In a medical context, it often relates to the functionality of the eye and visual system. There are two types of night vision:

1. Scotopic vision: This is the primary type of night vision, enabled by the rod cells in our retina which are highly sensitive to light but lack color vision. During twilight or night conditions, when light levels are low, the rods take over from the cone cells (which are responsible for color and daytime vision) and provide us with limited vision, typically in shades of gray.

2. Mesopic vision: This is a state between photopic (daytime) and scotopic (night-time) vision, where both rod and cone cells contribute to vision. It allows for better color discrimination and visual acuity compared to scotopic vision alone.

In some cases, night vision can be impaired due to eye conditions such as cataracts, glaucoma, or retinal disorders. There are also medical devices called night vision goggles that amplify available light to enhance a person's ability to see in low-light environments.

Rhodopsin, also known as visual purple, is a light-sensitive pigment found in the rods of the vertebrate retina. It is a complex protein molecule made up of two major components: an opsin protein and retinal, a form of vitamin A. When light hits the retinal in rhodopsin, it changes shape, which initiates a series of chemical reactions leading to the activation of the visual pathway and ultimately results in vision. This process is known as phototransduction. Rhodopsin plays a crucial role in low-light vision or scotopic vision.

Sensory thresholds are the minimum levels of stimulation that are required to produce a sensation in an individual, as determined through psychophysical testing. These tests measure the point at which a person can just barely detect the presence of a stimulus, such as a sound, light, touch, or smell.

There are two types of sensory thresholds: absolute and difference. Absolute threshold is the minimum level of intensity required to detect a stimulus 50% of the time. Difference threshold, also known as just noticeable difference (JND), is the smallest change in intensity that can be detected between two stimuli.

Sensory thresholds can vary between individuals and are influenced by factors such as age, attention, motivation, and expectations. They are often used in clinical settings to assess sensory function and diagnose conditions such as hearing or vision loss.

Retinal pigments refer to the light-sensitive chemicals found in the retina, specifically within the photoreceptor cells called rods and cones. The main types of retinal pigments are rhodopsin (also known as visual purple) in rods and iodopsins in cones. These pigments play a crucial role in the process of vision by absorbing light and initiating a series of chemical reactions that ultimately trigger nerve impulses, which are then transmitted to the brain and interpreted as visual images. Rhodopsin is more sensitive to lower light levels and is responsible for night vision, while iodopsins are sensitive to specific wavelengths of light and contribute to color vision.

Ocular vision refers to the ability to process and interpret visual information that is received by the eyes. This includes the ability to see clearly and make sense of the shapes, colors, and movements of objects in the environment. The ocular system, which includes the eye and related structures such as the optic nerve and visual cortex of the brain, works together to enable vision.

There are several components of ocular vision, including:

* Visual acuity: the clarity or sharpness of vision
* Field of vision: the extent of the visual world that is visible at any given moment
* Color vision: the ability to distinguish different colors
* Depth perception: the ability to judge the distance of objects in three-dimensional space
* Contrast sensitivity: the ability to distinguish an object from its background based on differences in contrast

Disorders of ocular vision can include refractive errors such as nearsightedness or farsightedness, as well as more serious conditions such as cataracts, glaucoma, and macular degeneration. These conditions can affect one or more aspects of ocular vision and may require medical treatment to prevent further vision loss.

Retinal cone photoreceptor cells are specialized neurons located in the retina of the eye, responsible for visual phototransduction and color vision. They are one of the two types of photoreceptors, with the other being rods, which are more sensitive to low light levels. Cones are primarily responsible for high-acuity, color vision during daylight or bright-light conditions.

There are three types of cone cells, each containing different photopigments that absorb light at distinct wavelengths: short (S), medium (M), and long (L) wavelengths, which correspond to blue, green, and red light, respectively. The combination of signals from these three types of cones allows the human visual system to perceive a wide range of colors and discriminate between them. Cones are densely packed in the central region of the retina, known as the fovea, which provides the highest visual acuity.

Vitamin A deficiency (VAD) is a condition that occurs when there is a lack of vitamin A in the diet. This essential fat-soluble vitamin plays crucial roles in vision, growth, cell division, reproduction, and immune system regulation.

In its severe form, VAD leads to xerophthalmia, which includes night blindness (nyctalopia) and keratomalacia - a sight-threatening condition characterized by dryness of the conjunctiva and cornea, with eventual ulceration and perforation. Other symptoms of VAD may include Bitot's spots (foamy, triangular, white spots on the conjunctiva), follicular hyperkeratosis (goose bump-like bumps on the skin), and increased susceptibility to infections due to impaired immune function.

Vitamin A deficiency is most prevalent in developing countries where diets are often low in animal source foods and high in plant-based foods with low bioavailability of vitamin A. It primarily affects children aged 6 months to 5 years, pregnant women, and lactating mothers. Prevention strategies include dietary diversification, food fortification, and supplementation programs.

Retinaldehyde, also known as retinal, is a form of vitamin A that is essential for vision. It is the aldehyde form of retinol (vitamin A alcohol) and is involved in the visual cycle, where it plays a crucial role in the process of converting light into electrical signals that are sent to the brain.

When light hits the retina, it activates a protein called rhodopsin, which contains retinaldehyde as one of its components. This activation causes a chemical change in retinaldehyde, leading to the generation of an electrical signal that is transmitted to the brain via the optic nerve.

Retinaldehyde is also involved in other physiological processes, including the regulation of gene expression and cell growth and differentiation. It can be synthesized in the body from beta-carotene, a pigment found in fruits and vegetables, or obtained directly from animal sources such as liver, fish liver oil, and dairy products.

Photic stimulation is a medical term that refers to the exposure of the eyes to light, specifically repetitive pulses of light, which is used as a method in various research and clinical settings. In neuroscience, it's often used in studies related to vision, circadian rhythms, and brain function.

In a clinical context, photic stimulation is sometimes used in the diagnosis of certain medical conditions such as seizure disorders (like epilepsy). By observing the response of the brain to this light stimulus, doctors can gain valuable insights into the functioning of the brain and the presence of any neurological disorders.

However, it's important to note that photic stimulation should be conducted under the supervision of a trained healthcare professional, as improper use can potentially trigger seizures in individuals who are susceptible to them.

Chlorofluorocarbons (CFCs) and methane are both greenhouse gases that contribute to global warming and climate change. However, they are distinct substances with different chemical structures and sources.

Chlorofluorocarbons (CFCs) are synthetic compounds made up of carbon, chlorine, and fluorine atoms. They were commonly used in refrigerants, aerosol sprays, and foam blowing agents until they were phased out due to their harmful effects on the ozone layer. CFCs have high global warming potential, meaning that they trap heat in the atmosphere many times more effectively than carbon dioxide.

Methane, on the other hand, is a naturally occurring gas made up of one carbon atom and four hydrogen atoms (CH4). It is produced by the decomposition of organic matter, such as in landfills, wetlands, and the digestive tracts of animals like cattle. Methane is also released during the extraction and transportation of fossil fuels like coal, oil, and natural gas. While methane has a shorter lifespan in the atmosphere than CFCs, it is an even more potent greenhouse gas, trapping heat at a rate 25 times greater than carbon dioxide over a 100-year period.

Therefore, while both CFCs and methane are harmful to the climate, they are distinct substances with different sources and impacts.

A Cathode Ray Tube (CRT) is a vacuum tube that contains one or more electron guns and a fluorescent screen used to view images. In a CRT, the electron gun emits a beam of electrons that are accelerated towards the fluorescent screen. The electrons strike the phosphor-coated screen, causing it to emit light and create images.

CRTs were commonly used in older television sets and computer monitors before being replaced by flat-panel displays such as LCDs and plasmas. CRTs are still used in some medical equipment, such as cathode ray oscilloscopes and X-ray imaging systems.

Medical Definition of Vitamin A:

Vitamin A is a fat-soluble vitamin that is essential for normal vision, immune function, and cell growth. It is also an antioxidant that helps protect the body's cells from damage caused by free radicals. Vitamin A can be found in two main forms: preformed vitamin A, which is found in animal products such as dairy, fish, and meat, particularly liver; and provitamin A carotenoids, which are found in plant-based foods such as fruits, vegetables, and vegetable oils.

The most active form of vitamin A is retinoic acid, which plays a critical role in the development and maintenance of the heart, lungs, kidneys, and other organs. Vitamin A deficiency can lead to night blindness, dry skin, and increased susceptibility to infections. Chronic vitamin A toxicity can cause nausea, dizziness, headaches, coma, and even death.

Flicker Fusion is the frequency at which an intermittent light stimulus appears to be completely steady or continuous to the average human observer. In other words, it is the rate at which a flickering light source transitions from being perceived as distinct flashes to a smooth and constant emission of light. The exact threshold can vary depending on factors such as the intensity of the light, its size, and the observer's visual acuity.

Flicker Fusion has important implications in various fields, including visual perception research, display technology, and neurology. In clinical settings, assessing a patient's flicker fusion threshold can help diagnose or monitor conditions affecting the nervous system, such as multiple sclerosis or migraines.

"Ocular physiological phenomena" is not a standardized medical term with a specific definition. However, I can provide some examples of ocular physiological phenomena, which refer to various normal functions and processes that occur in the eye. Here are a few examples:

1. Accommodation: The ability of the eye to change optical power to maintain a clear image or focus on an object as its distance varies. This is primarily achieved by changing the curvature of the lens through the action of the ciliary muscles.
2. Pupillary reflex: The automatic adjustment of the pupil's size in response to changes in light intensity. In bright light, the pupil constricts (miosis), while in dim light, it dilates (mydriasis). This reflex helps regulate the amount of light that enters the eye.
3. Tear production: The continuous secretion of tears by the lacrimal glands to keep the eyes moist and protected from dust, microorganisms, and other foreign particles.
4. Extraocular muscle function: The coordinated movement of the six extraocular muscles that control eyeball rotation and enable various gaze directions.
5. Color vision: The ability to perceive and distinguish different colors based on the sensitivity of photoreceptor cells (cones) in the retina to specific wavelengths of light.
6. Dark adaptation: The process by which the eyes adjust to low-light conditions, improving visual sensitivity primarily through changes in the rod photoreceptors' sensitivity and pupil dilation.
7. Light adaptation: The ability of the eye to adjust to different levels of illumination, mainly through alterations in pupil size and photoreceptor cell response.

These are just a few examples of ocular physiological phenomena. There are many more processes and functions that occur within the eye, contributing to our visual perception and overall eye health.

Photoreceptor cells in vertebrates are specialized types of neurons located in the retina of the eye that are responsible for converting light stimuli into electrical signals. These cells are primarily responsible for the initial process of vision and have two main types: rods and cones.

Rods are more numerous and are responsible for low-light vision or scotopic vision, enabling us to see in dimly lit conditions. They do not contribute to color vision but provide information about the shape and movement of objects.

Cones, on the other hand, are less numerous and are responsible for color vision and high-acuity vision or photopic vision. There are three types of cones, each sensitive to different wavelengths of light: short (S), medium (M), and long (L) wavelengths, which correspond to blue, green, and red, respectively. The combination of signals from these three types of cones allows us to perceive a wide range of colors.

Both rods and cones contain photopigments that consist of a protein called opsin and a light-sensitive chromophore called retinal. When light hits the photopigment, it triggers a series of chemical reactions that ultimately lead to the generation of an electrical signal that is transmitted to the brain via the optic nerve. This process enables us to see and perceive our visual world.

Biological adaptation is the process by which a organism becomes better suited to its environment over generations as a result of natural selection. It involves changes in an organism's structure, metabolism, or behavior that increase its fitness, or reproductive success, in a given environment. These changes are often genetic and passed down from one generation to the next through the process of inheritance.

Examples of biological adaptation include the development of camouflage in animals, the ability of plants to photosynthesize, and the development of antibiotic resistance in bacteria. Biological adaptation is an important concept in the field of evolutionary biology and helps to explain the diversity of life on Earth.

Retinoids are a class of chemical compounds that are derivatives of vitamin A. They are widely used in dermatology for the treatment of various skin conditions, including acne, psoriasis, and photoaging. Retinoids can help to reduce inflammation, improve skin texture and tone, and stimulate collagen production.

Retinoids work by binding to specific receptors in the skin cells, which triggers a series of biochemical reactions that regulate gene expression and promote cell differentiation and turnover. This can help to unclog pores, reduce the appearance of fine lines and wrinkles, and improve the overall health and appearance of the skin.

There are several different types of retinoids used in skincare products, including retinoic acid, retinaldehyde, and retinol. Retinoic acid is the most potent form of retinoid and is available by prescription only. Retinaldehyde and retinol are weaker forms of retinoid that can be found in over-the-counter skincare products.

While retinoids can be highly effective for treating various skin conditions, they can also cause side effects such as dryness, irritation, and sensitivity to the sun. It is important to use retinoids as directed by a healthcare professional and to follow proper sun protection measures when using these products.

Retinal degeneration is a broad term that refers to the progressive loss of photoreceptor cells (rods and cones) in the retina, which are responsible for converting light into electrical signals that are sent to the brain. This process can lead to vision loss or blindness. There are many different types of retinal degeneration, including age-related macular degeneration, retinitis pigmentosa, and Stargardt's disease, among others. These conditions can have varying causes, such as genetic mutations, environmental factors, or a combination of both. Treatment options vary depending on the specific type and progression of the condition.

"Fundus Oculi" is a medical term that refers to the back part of the interior of the eye, including the optic disc, macula, fovea, retinal vasculature, and peripheral retina. It is the area where light is focused and then transmitted to the brain via the optic nerve, forming visual images. Examinations of the fundus oculi are crucial for detecting various eye conditions such as diabetic retinopathy, macular degeneration, glaucoma, and other retinal diseases. The examination is typically performed using an ophthalmoscope or a specialized camera called a retinal camera.

Retinitis pigmentosa (RP) is a group of rare, genetic disorders that involve a breakdown and loss of cells in the retina - a light-sensitive tissue located at the back of the eye. The retina converts light into electrical signals which are then sent to the brain and interpreted as visual images.

In RP, the cells that detect light (rods and cones) degenerate more slowly than other cells in the retina, leading to a progressive loss of vision. Symptoms typically begin in childhood with night blindness (difficulty seeing in low light), followed by a gradual narrowing of the visual field (tunnel vision). Over time, this can lead to significant vision loss and even blindness.

The condition is usually inherited and there are several different genes that have been associated with RP. The diagnosis is typically made based on a combination of genetic testing, family history, and clinical examination. Currently, there is no cure for RP, but researchers are actively working to develop new treatments that may help slow or stop the progression of the disease.

Urodela is not a medical term, but a taxonomic category in the field of biology. It refers to a group of amphibians commonly known as newts and salamanders. These creatures are characterized by their slender bodies, moist skin, and four legs. They undergo a process of metamorphosis during their development, transitioning from an aquatic larval stage to a terrestrial adult stage.

While not a medical term itself, understanding the biology and ecology of Urodela can be relevant in fields such as environmental health and toxicology, where these animals may serve as indicators of ecosystem health or potential subjects for studying the effects of pollutants on living organisms.

Light signal transduction is a biological process that refers to the way in which cells convert light signals into chemical or electrical responses. This process typically involves several components, including a light-sensitive receptor (such as a photopigment), a signaling molecule (like a G-protein or calcium ion), and an effector protein that triggers a downstream response.

In the visual system, for example, light enters the eye and activates photoreceptor cells in the retina. These cells contain a light-sensitive pigment called rhodopsin, which undergoes a chemical change when struck by a photon of light. This change triggers a cascade of signaling events that ultimately lead to the transmission of visual information to the brain.

Light signal transduction is also involved in other biological processes, such as the regulation of circadian rhythms and the synthesis of vitamin D. In these cases, specialized cells contain light-sensitive receptors that allow them to detect changes in ambient light levels and adjust their physiology accordingly.

Overall, light signal transduction is a critical mechanism by which organisms are able to sense and respond to their environment.

Color vision defects, also known as color blindness, are conditions in which a person has difficulty distinguishing between certain colors. The most common types of color vision defects involve the inability to distinguish between red and green or blue and yellow. These deficiencies result from an alteration or absence of one or more of the three types of cone cells in the retina that are responsible for normal color vision.

In red-green color vision defects, there is a problem with either the red or green cones, or both. This results in difficulty distinguishing between these two colors and their shades. Protanopia is a type of red-green color vision defect where there is an absence of red cone cells, making it difficult to distinguish between red and green as well as between red and black or green and black. Deuteranopia is another type of red-green color vision defect where there is an absence of green cone cells, resulting in similar difficulties distinguishing between red and green, as well as between blue and yellow.

Blue-yellow color vision defects are less common than red-green color vision defects. Tritanopia is a type of blue-yellow color vision defect where there is an absence of blue cone cells, making it difficult to distinguish between blue and yellow, as well as between blue and purple or yellow and pink.

Color vision defects are usually inherited and present from birth, but they can also result from eye diseases, chemical exposure, aging, or medication side effects. They affect both men and women, although red-green color vision defects are more common in men than in women. People with color vision defects may have difficulty with tasks that require color discrimination, such as matching clothes, selecting ripe fruit, reading colored maps, or identifying warning signals. However, most people with mild to moderate color vision defects can adapt and function well in daily life.

In medical terms, "ether" is an outdated term that was used to refer to a group of compounds known as diethyl ethers. The most common member of this group, and the one most frequently referred to as "ether," is diethyl ether, also known as sulfuric ether or simply ether.

Diethyl ether is a highly volatile, flammable liquid that was once widely used as an anesthetic agent in surgical procedures. It has a characteristic odor and produces a state of unconsciousness when inhaled, allowing patients to undergo surgery without experiencing pain. However, due to its numerous side effects, such as nausea, vomiting, and respiratory depression, as well as the risk of explosion or fire during use, it has largely been replaced by safer and more effective anesthetic agents.

It's worth noting that "ether" also has other meanings in different contexts, including a term used to describe a substance that produces a feeling of detachment from reality or a sense of unreality, as well as a class of organic compounds characterized by the presence of an ether group (-O-, a functional group consisting of an oxygen atom bonded to two alkyl or aryl groups).

The digestive system, also known as the gastrointestinal (GI) tract, is a series of organs that process food and liquids into nutrients and waste. Digestive system diseases refer to any conditions that affect the normal functioning of this system, leading to impaired digestion, absorption, or elimination of food and fluids.

Some common examples of digestive system diseases include:

1. Gastroesophageal Reflux Disease (GERD): A condition where stomach acid flows back into the esophagus, causing symptoms such as heartburn, chest pain, and difficulty swallowing.
2. Peptic Ulcer Disease: Sores or ulcers that develop in the lining of the stomach or duodenum, often caused by bacterial infection or long-term use of nonsteroidal anti-inflammatory drugs (NSAIDs).
3. Inflammatory Bowel Disease (IBD): A group of chronic inflammatory conditions that affect the intestines, including Crohn's disease and ulcerative colitis.
4. Irritable Bowel Syndrome (IBS): A functional gastrointestinal disorder characterized by abdominal pain, bloating, and changes in bowel habits.
5. Celiac Disease: An autoimmune disorder where the ingestion of gluten leads to damage in the small intestine, impairing nutrient absorption.
6. Diverticular Disease: A condition that affects the colon, characterized by the formation of small pouches or sacs (diverticula) that can become inflamed or infected.
7. Constipation: A common digestive system issue where bowel movements occur less frequently than usual or are difficult to pass.
8. Diarrhea: Loose, watery stools that occur more frequently than normal, often accompanied by cramps and bloating.
9. Gallstones: Small, hard deposits that form in the gallbladder, causing pain, inflammation, and potential blockages of the bile ducts.
10. Hepatitis: Inflammation of the liver, often caused by viral infections or toxins, leading to symptoms such as jaundice, fatigue, and abdominal pain.

These are just a few examples of digestive system disorders that can affect overall health and quality of life. If you experience any persistent or severe digestive symptoms, it is important to seek medical attention from a healthcare professional.

Rhodopsin, also known as visual purple, is a light-sensitive protein found in the rods of the eye's retina. It is a type of opsin, a class of proteins that are activated by light and play a crucial role in vision. Rhodopsin is composed of two parts: an apoprotein called opsin and a chromophore called 11-cis-retinal. When light hits the retina, it changes the shape of the 11-cis-retinal, which in turn activates the rhodopsin protein. This activation triggers a series of chemical reactions that ultimately lead to the transmission of a visual signal to the brain. Rhodopsin is highly sensitive to light and allows for vision in low-light conditions.

Opsins are a type of protein that are sensitive to light and play a crucial role in vision. They are found in the photoreceptor cells of the retina, which are the specialized cells in the eye that detect light. Opsins are activated by light, which triggers a series of chemical reactions that ultimately result in the transmission of a signal to the brain, allowing us to see.

There are several different types of opsins, including rhodopsin and the cone pigments, which are found in the rods and cones of the retina, respectively. Rhodopsin is responsible for dim-light vision, while the cone pigments are involved in color vision and bright-light vision.

Opsins belong to a larger family of proteins called G protein-coupled receptors (GPCRs), which are involved in many different physiological processes in the body. In addition to their role in vision, opsins have also been found to be involved in other light-dependent processes, such as the regulation of circadian rhythms and the entrainment of the biological clock.

Psychophysiology is a branch of psychology that deals with the scientific study of the relationships between physical processes (such as heart rate, skin conductance, brain activity) and mental or emotional states. It involves the use of physiological measures to understand psychological phenomena and how they relate to behavior. This field of study often employs various research methods, including laboratory experiments, observational studies, and neuroimaging techniques, to examine these relationships in both healthy individuals and those with psychological disorders. The goal of psychophysiology is to better understand the underlying mechanisms that contribute to emotional, cognitive, and behavioral functioning.

Color perception refers to the ability to detect, recognize, and differentiate various colors and color patterns in the visual field. This complex process involves the functioning of both the eyes and the brain.

The eye's retina contains two types of photoreceptor cells called rods and cones. Rods are more sensitive to light and dark changes and help us see in low-light conditions, but they do not contribute much to color vision. Cones, on the other hand, are responsible for color perception and function best in well-lit conditions.

There are three types of cone cells, each sensitive to a particular range of wavelengths corresponding to blue, green, and red colors. The combination of signals from these three types of cones allows us to perceive a wide spectrum of colors.

The brain then interprets these signals and translates them into the perception of different colors and hues. It is important to note that color perception can be influenced by various factors, including cultural background, personal experiences, and even language. Some individuals may also have deficiencies in color perception due to genetic or acquired conditions, such as color blindness or cataracts.

Color perception tests are a type of examination used to evaluate an individual's ability to perceive and distinguish different colors. These tests typically consist of a series of plates or images that contain various patterns or shapes displayed in different colors. The person being tested is then asked to identify or match the colors based on specific instructions.

There are several types of color perception tests, including:

1. Ishihara Test: This is a commonly used test for red-green color deficiency. It consists of a series of plates with circles made up of dots in different sizes and colors. Within these circles, there may be a number or symbol visible only to those with normal color vision or to those with specific types of color blindness.
2. Farnsworth D-15 Test: This test measures an individual's ability to arrange colored caps in a specific order based on their hue. It is often used to diagnose and monitor the progression of color vision deficiencies.
3. Hardy-Rand-Rittler (HRR) Test: This is another type of color arrangement test that measures an individual's ability to distinguish between different colors based on their hue, saturation, and brightness.
4. Color Discrimination Tests: These tests measure an individual's ability to distinguish between two similar colors that are presented side by side or in close proximity.
5. Anomaloscope Test: This is a more sophisticated test that measures the degree of color vision deficiency by asking the person to match the brightness and hue of two lights.

Color perception tests are often used in occupational settings, such as aviation, military, and manufacturing, where color discrimination is critical for safety and performance. They may also be used in educational and clinical settings to diagnose and monitor color vision deficiencies.

Cis-trans isomeres are molecules that have the same molecular formula and skeletal structure, but differ in the arrangement of their atoms around a double bond. In a cis isomer, the two larger groups or atoms are on the same side of the double bond, while in a trans isomer, they are on opposite sides.

Cis-trans isomerases are enzymes that catalyze the interconversion between cis and trans isomers of various molecules, such as fatty acids, steroids, and retinals. These enzymes play important roles in various biological processes, including membrane fluidity, vision, and the biosynthesis of hormones and other signaling molecules.

Examples of cis-trans isomerases include:

* Fatty acid desaturases, which introduce double bonds into fatty acids and can convert trans isomers to cis isomers
* Retinal isomerases, which interconvert the cis and trans isomers of retinal, a molecule involved in vision
* Steroid isomerases, which catalyze the interconversion of various steroids, including cholesterol and its derivatives.

"Ambystoma" is a genus of salamanders, also known as the mole salamanders. These amphibians are characterized by their fossorial (burrowing) habits and typically have four limbs, a tail, and moist skin. They are found primarily in North America, with a few species in Asia and Europe. Some well-known members of this genus include the axolotl (A. mexicanum), which is famous for its ability to regenerate lost body parts, and the spotted salamander (A. maculatum). The name "Ambystoma" comes from the Greek words "amblys," meaning blunt, and "stoma," meaning mouth, in reference to the wide, blunt snout of these animals.

In the field of medicine, "time factors" refer to the duration of symptoms or time elapsed since the onset of a medical condition, which can have significant implications for diagnosis and treatment. Understanding time factors is crucial in determining the progression of a disease, evaluating the effectiveness of treatments, and making critical decisions regarding patient care.

For example, in stroke management, "time is brain," meaning that rapid intervention within a specific time frame (usually within 4.5 hours) is essential to administering tissue plasminogen activator (tPA), a clot-busting drug that can minimize brain damage and improve patient outcomes. Similarly, in trauma care, the "golden hour" concept emphasizes the importance of providing definitive care within the first 60 minutes after injury to increase survival rates and reduce morbidity.

Time factors also play a role in monitoring the progression of chronic conditions like diabetes or heart disease, where regular follow-ups and assessments help determine appropriate treatment adjustments and prevent complications. In infectious diseases, time factors are crucial for initiating antibiotic therapy and identifying potential outbreaks to control their spread.

Overall, "time factors" encompass the significance of recognizing and acting promptly in various medical scenarios to optimize patient outcomes and provide effective care.

Macular degeneration, also known as age-related macular degeneration (AMD), is a medical condition that affects the central part of the retina, called the macula. The macula is responsible for sharp, detailed vision, which is necessary for activities such as reading, driving, and recognizing faces.

In AMD, there is a breakdown or deterioration of the macula, leading to gradual loss of central vision. There are two main types of AMD: dry (atrophic) and wet (exudative). Dry AMD is more common and progresses more slowly, while wet AMD is less common but can cause rapid and severe vision loss if left untreated.

The exact causes of AMD are not fully understood, but risk factors include age, smoking, family history, high blood pressure, obesity, and exposure to sunlight. While there is no cure for AMD, treatments such as vitamin supplements, laser therapy, and medication injections can help slow its progression and reduce the risk of vision loss.

Bacteriorhodopsins are a type of protein found in certain archaea, a group of single-celled microorganisms. They are most commonly found in the archaea of the genus Halobacterium, which live in extremely salty environments such as salt lakes and solar salterns.

Bacteriorhodopsins are embedded in the cell membrane of these archaea and contain a retinal molecule, which is a type of vitamin A derivative. When exposed to light, the retinal changes shape, which causes a conformational change in the bacteriorhodopsin protein. This leads to the pumping of protons (hydrogen ions) across the cell membrane, generating a proton gradient.

The proton gradient created by bacteriorhodopsins can be used to generate ATP, which is the main energy currency of the cell. Bacteriorhodopsins are therefore involved in energy production in these archaea and are often referred to as light-driven proton pumps. They have also been studied extensively for their potential applications in optoelectronics and biotechnology.

A pupil, in medical terms, refers to the circular opening in the center of the iris (the colored part of the eye) that allows light to enter and reach the retina. The size of the pupil can change involuntarily in response to light intensity and emotional state, as well as voluntarily through certain eye exercises or with the use of eye drops. Pupillary reactions are important in clinical examinations as they can provide valuable information about the nervous system's functioning, particularly the brainstem and cranial nerves II and III.

Visual acuity is a measure of the sharpness or clarity of vision. It is usually tested by reading an eye chart from a specific distance, such as 20 feet (6 meters). The standard eye chart used for this purpose is called the Snellen chart, which contains rows of letters that decrease in size as you read down the chart.

Visual acuity is typically expressed as a fraction, with the numerator representing the testing distance and the denominator indicating the smallest line of type that can be read clearly. For example, if a person can read the line on the eye chart that corresponds to a visual acuity of 20/20, it means they have normal vision at 20 feet. If their visual acuity is 20/40, it means they must be as close as 20 feet to see what someone with normal vision can see at 40 feet.

It's important to note that visual acuity is just one aspect of overall vision and does not necessarily reflect other important factors such as peripheral vision, depth perception, color vision, or contrast sensitivity.

I'm sorry for any confusion, but "Nepal" is not a medical term. It is a country located in South Asia, between China and India. If you have any questions about medical terminology or health-related topics, I would be happy to try and help answer those for you.

The fovea centralis, also known as the macula lutea, is a small pit or depression located in the center of the retina, an light-sensitive tissue at the back of the eye. It is responsible for sharp, detailed vision (central vision) and color perception. The fovea contains only cones, the photoreceptor cells that are responsible for color vision and high visual acuity. It has a higher concentration of cones than any other area in the retina, allowing it to provide the greatest detail and color discrimination. The center of the fovea is called the foveola, which contains the highest density of cones and is avascular, meaning it lacks blood vessels to avoid interfering with the light passing through to the photoreceptor cells.

Contrast sensitivity is a measure of the ability to distinguish between an object and its background based on differences in contrast, rather than differences in luminance. Contrast refers to the difference in light intensity between an object and its immediate surroundings. Contrast sensitivity is typically measured using specially designed charts that have patterns of parallel lines with varying widths and contrast levels.

In clinical settings, contrast sensitivity is often assessed as part of a comprehensive visual examination. Poor contrast sensitivity can affect a person's ability to perform tasks such as reading, driving, or distinguishing objects from their background, especially in low-light conditions. Reduced contrast sensitivity is a common symptom of various eye conditions, including cataracts, glaucoma, and age-related macular degeneration.

Photometry is the measurement and study of light, specifically its brightness or luminous intensity. In a medical context, photometry is often used in ophthalmology to describe diagnostic tests that measure the amount and type of light that is perceived by the eye. This can help doctors diagnose and monitor various eye conditions and diseases, such as cataracts, glaucoma, and retinal disorders. Photometry may also be used in other medical fields, such as dermatology, to evaluate the effects of different types of light on skin conditions.

The Bruch membrane is a thin, layered structure that separates the retina from the choroid in the eye. It is composed of five layers: the basement membrane of the retinal pigment epithelium (RPE), the inner collagenous layer, the elastic layer, the outer collagenous layer, and the basement membrane of the choriocapillaris. The Bruch membrane provides structural support to the RPE and serves as a barrier between the retina and the choroid, allowing for the selective transport of nutrients and waste products. It also plays a role in maintaining the health of the photoreceptors in the retina. Damage to the Bruch membrane is associated with age-related macular degeneration (AMD), a leading cause of vision loss in older adults.

Electrooculography (EOG) is a technique for measuring the resting potential of the eye and the changes in this potential that occur with eye movements. It involves placing electrodes near the eyes to detect the small electric fields generated by the movement of the eyeball within the surrounding socket. This technique is used in research and clinical settings to study eye movements and their control, as well as in certain diagnostic applications such as assessing the function of the oculomotor system in patients with neurological disorders.

Retinal diseases refer to a group of conditions that affect the retina, which is the light-sensitive tissue located at the back of the eye. The retina is responsible for converting light into electrical signals that are sent to the brain and interpreted as visual images. Retinal diseases can cause vision loss or even blindness, depending on their severity and location in the retina.

Some common retinal diseases include:

1. Age-related macular degeneration (AMD): A progressive disease that affects the central part of the retina called the macula, causing blurred or distorted vision.
2. Diabetic retinopathy: A complication of diabetes that can damage the blood vessels in the retina, leading to vision loss.
3. Retinal detachment: A serious condition where the retina becomes separated from its underlying tissue, requiring immediate medical attention.
4. Macular edema: Swelling or thickening of the macula due to fluid accumulation, which can cause blurred vision.
5. Retinitis pigmentosa: A group of inherited eye disorders that affect the retina's ability to respond to light, causing progressive vision loss.
6. Macular hole: A small break in the macula that can cause distorted or blurry vision.
7. Retinal vein occlusion: Blockage of the retinal veins that can lead to bleeding, swelling, and potential vision loss.

Treatment for retinal diseases varies depending on the specific condition and its severity. Some treatments include medication, laser therapy, surgery, or a combination of these options. Regular eye exams are essential for early detection and treatment of retinal diseases.

In the context of medicine and pharmacology, "kinetics" refers to the study of how a drug moves throughout the body, including its absorption, distribution, metabolism, and excretion (often abbreviated as ADME). This field is called "pharmacokinetics."

1. Absorption: This is the process of a drug moving from its site of administration into the bloodstream. Factors such as the route of administration (e.g., oral, intravenous, etc.), formulation, and individual physiological differences can affect absorption.

2. Distribution: Once a drug is in the bloodstream, it gets distributed throughout the body to various tissues and organs. This process is influenced by factors like blood flow, protein binding, and lipid solubility of the drug.

3. Metabolism: Drugs are often chemically modified in the body, typically in the liver, through processes known as metabolism. These changes can lead to the formation of active or inactive metabolites, which may then be further distributed, excreted, or undergo additional metabolic transformations.

4. Excretion: This is the process by which drugs and their metabolites are eliminated from the body, primarily through the kidneys (urine) and the liver (bile).

Understanding the kinetics of a drug is crucial for determining its optimal dosing regimen, potential interactions with other medications or foods, and any necessary adjustments for special populations like pediatric or geriatric patients, or those with impaired renal or hepatic function.

The pigment epithelium of the eye, also known as the retinal pigment epithelium (RPE), is a layer of cells located between the photoreceptor cells of the retina and the choroid, which is the vascular layer of the eye. The RPE plays a crucial role in maintaining the health and function of the photoreceptors by providing them with nutrients, removing waste products, and helping to regulate the light that enters the eye.

The RPE cells contain pigment granules that absorb excess light, preventing it from scattering within the eye and improving visual acuity. They also help to create a barrier between the retina and the choroid, which is important for maintaining the proper functioning of the photoreceptors. Additionally, the RPE plays a role in the regeneration of visual pigments in the photoreceptor cells, allowing us to see in different light conditions.

Damage to the RPE can lead to various eye diseases and conditions, including age-related macular degeneration (AMD), which is a leading cause of vision loss in older adults.

Fungi, in the context of medical definitions, are a group of eukaryotic organisms that include microorganisms such as yeasts and molds, as well as the more familiar mushrooms. The study of fungi is known as mycology.

Fungi can exist as unicellular organisms or as multicellular filamentous structures called hyphae. They are heterotrophs, which means they obtain their nutrients by decomposing organic matter or by living as parasites on other organisms. Some fungi can cause various diseases in humans, animals, and plants, known as mycoses. These infections range from superficial, localized skin infections to systemic, life-threatening invasive diseases.

Examples of fungal infections include athlete's foot (tinea pedis), ringworm (dermatophytosis), candidiasis (yeast infection), histoplasmosis, coccidioidomycosis, and aspergillosis. Fungal infections can be challenging to treat due to the limited number of antifungal drugs available and the potential for drug resistance.

Visual perception refers to the ability to interpret and organize information that comes from our eyes to recognize and understand what we are seeing. It involves several cognitive processes such as pattern recognition, size estimation, movement detection, and depth perception. Visual perception allows us to identify objects, navigate through space, and interact with our environment. Deficits in visual perception can lead to learning difficulties and disabilities.

I'm sorry for any confusion, but "photochemistry" is not a term typically used in medical definitions. Photochemistry is a branch of chemistry that deals with the chemical effects of light. It involves the absorption of light by a substance, which can lead to the promotion of an electron to a higher energy state, and subsequently result in various chemical reactions.

In a medical context, photochemical processes might be discussed in relation to certain therapies or diagnostic techniques, such as photodynamic therapy for cancer treatment, where a photosensitizing agent is used that reacts with light to produce singlet oxygen or other reactive species to destroy nearby cells. However, it's not a term used to define a specific medical condition or concept in the same way that one might define "inflammation" or "metabolism."

Vision disorders refer to a wide range of conditions that affect the visual system and result in various symptoms, such as blurry vision, double vision, distorted vision, impaired depth perception, and difficulty with visual tracking or focusing. These disorders can be categorized into several types, including:

1. Refractive errors: These occur when the shape of the eye prevents light from focusing directly on the retina, resulting in blurry vision. Examples include myopia (nearsightedness), hyperopia (farsightedness), astigmatism, and presbyopia (age-related loss of near vision).
2. Strabismus: Also known as crossed eyes or walleye, strabismus is a misalignment of the eyes where they point in different directions, which can lead to double vision or loss of depth perception.
3. Amblyopia: Often called lazy eye, amblyopia is a condition where one eye has reduced vision due to lack of proper visual development during childhood. It may be caused by strabismus, refractive errors, or other factors that interfere with normal visual development.
4. Accommodative disorders: These involve problems with the focusing ability of the eyes, such as convergence insufficiency (difficulty focusing on close objects) and accommodative dysfunction (inability to maintain clear vision at different distances).
5. Binocular vision disorders: These affect how the eyes work together as a team, leading to issues like poor depth perception, eye strain, and headaches. Examples include convergence insufficiency, divergence excess, and suppression.
6. Ocular motility disorders: These involve problems with eye movement, such as nystagmus (involuntary eye movements), strabismus, or restricted extraocular muscle function.
7. Visual processing disorders: These affect the brain's ability to interpret and make sense of visual information, even when the eyes themselves are healthy. Symptoms may include difficulty with reading, recognizing shapes and objects, and understanding spatial relationships.
8. Low vision: This term refers to significant visual impairment that cannot be fully corrected with glasses, contact lenses, medication, or surgery. It includes conditions like macular degeneration, diabetic retinopathy, glaucoma, and cataracts.
9. Blindness: Complete loss of sight in both eyes, which can be caused by various factors such as injury, disease, or genetic conditions.

Visual fields refer to the total area in which objects can be seen while keeping the eyes focused on a central point. It is the entire area that can be observed using peripheral (side) vision while the eye gazes at a fixed point. A visual field test is used to detect blind spots or gaps (scotomas) in a person's vision, which could indicate various medical conditions such as glaucoma, retinal damage, optic nerve disease, brain tumors, or strokes. The test measures both the central and peripheral vision and maps the entire area that can be seen when focusing on a single point.

A visual field test is a method used to measure an individual's entire scope of vision, which includes what can be seen straight ahead and in peripheral (or side) vision. During the test, the person being tested is asked to focus on a central point while gradually identifying the appearance of objects moving into their peripheral vision. The visual field test helps detect blind spots (scotomas) or gaps in the visual field, which can be caused by various conditions such as glaucoma, brain injury, optic nerve damage, or retinal disorders. It's an essential tool for diagnosing and monitoring eye-related diseases and conditions.

"Cat" is a common name that refers to various species of small carnivorous mammals that belong to the family Felidae. The domestic cat, also known as Felis catus or Felis silvestris catus, is a popular pet and companion animal. It is a subspecies of the wildcat, which is found in Europe, Africa, and Asia.

Domestic cats are often kept as pets because of their companionship, playful behavior, and ability to hunt vermin. They are also valued for their ability to provide emotional support and therapy to people. Cats are obligate carnivores, which means that they require a diet that consists mainly of meat to meet their nutritional needs.

Cats are known for their agility, sharp senses, and predatory instincts. They have retractable claws, which they use for hunting and self-defense. Cats also have a keen sense of smell, hearing, and vision, which allow them to detect prey and navigate their environment.

In medical terms, cats can be hosts to various parasites and diseases that can affect humans and other animals. Some common feline diseases include rabies, feline leukemia virus (FeLV), feline immunodeficiency virus (FIV), and toxoplasmosis. It is important for cat owners to keep their pets healthy and up-to-date on vaccinations and preventative treatments to protect both the cats and their human companions.

Eye proteins, also known as ocular proteins, are specific proteins that are found within the eye and play crucial roles in maintaining proper eye function and health. These proteins can be found in various parts of the eye, including the cornea, iris, lens, retina, and other structures. They perform a wide range of functions, such as:

1. Structural support: Proteins like collagen and elastin provide strength and flexibility to the eye's tissues, enabling them to maintain their shape and withstand mechanical stress.
2. Light absorption and transmission: Proteins like opsins and crystallins are involved in capturing and transmitting light signals within the eye, which is essential for vision.
3. Protection against damage: Some eye proteins, such as antioxidant enzymes and heat shock proteins, help protect the eye from oxidative stress, UV radiation, and other environmental factors that can cause damage.
4. Regulation of eye growth and development: Various growth factors and signaling molecules, which are protein-based, contribute to the proper growth, differentiation, and maintenance of eye tissues during embryonic development and throughout adulthood.
5. Immune defense: Proteins involved in the immune response, such as complement components and immunoglobulins, help protect the eye from infection and inflammation.
6. Maintenance of transparency: Crystallin proteins in the lens maintain its transparency, allowing light to pass through unobstructed for clear vision.
7. Neuroprotection: Certain eye proteins, like brain-derived neurotrophic factor (BDNF), support the survival and function of neurons within the retina, helping to preserve vision.

Dysfunction or damage to these eye proteins can contribute to various eye disorders and diseases, such as cataracts, age-related macular degeneration, glaucoma, diabetic retinopathy, and others.

Electrophysiology is a branch of medicine that deals with the electrical activities of the body, particularly the heart. In a medical context, electrophysiology studies (EPS) are performed to assess abnormal heart rhythms (arrhythmias) and to evaluate the effectiveness of certain treatments, such as medication or pacemakers.

During an EPS, electrode catheters are inserted into the heart through blood vessels in the groin or neck. These catheters can record the electrical activity of the heart and stimulate it to help identify the source of the arrhythmia. The information gathered during the study can help doctors determine the best course of treatment for each patient.

In addition to cardiac electrophysiology, there are also other subspecialties within electrophysiology, such as neuromuscular electrophysiology, which deals with the electrical activity of the nervous system and muscles.

Dark adaptation gets weaker as people age, partially because the pupil of the eye cannot open as widely in older people. Color ... Dark Adaptation Threshold (DAT) is a vision test that measures the adjustment of the eye occurring under low levels of ... In order to perform this test, the child is asked to sit in the dark for a half-hour. This allows the eyes to be most sensitive ... Once the child can no longer see the spots, the dark adapted threshold is determined. The DAT test lasts for about 10 to 15 ...
This is called dark adaptation. Auditory adaptation, as perceptual adaptation with other senses, is the process by which ... There is fast adaptation and slow adaptation. Fast adaptation occurs immediately after a stimulus is presented i.e., within ... Neural adaptation or sensory adaptation is a gradual decrease over time in the responsiveness of the sensory system to a ... The two classes of neural adaptation may rely on very different physiological mechanisms. The time scale over which adaptation ...
However, an RI higher than 6.5 indicates impaired dark adaptation. Numerous clinical studies have shown that dark adaptation ... dark adaptation using an instrument known as a dark adaptometer. Currently, there is one commercially available dark ... Adaptation,+Ocular at the U.S. National Library of Medicine Medical Subject Headings (MeSH) Light and Dark Adaptation by ... Dark adaptation was further accelerated following 75 days of treatment. A subsequent study by Kemp et al. studied dark ...
"Dark Adaptation Podcast". Dark Adaptation Podcast. Retrieved 2021-12-12. "The best Canadian podcasts to listen to - according ... "North Vancouver podcast 'The Hopeful' is a ray of light in a dark year". Vancouver Is Awesome. Archived from the original on ...
ISBN 978-0-8108-6378-1. "Dark Adaptation - an overview , ScienceDirect Topics". www.sciencedirect.com. Andrew Wilson (10 March ... Wikimedia Commons has media related to A Dark-Adapted Eye. A Dark-Adapted Eye at IMDb (Articles with short description, Short ... "Revisiting the Edgar Awards: 1987's A Dark-Adapted Eye by Barbara Vine". Criminal Element. 23 August 2019. "A Dark Adapted Eye ... A dark-adapted eye is one that has adjusted to darkness so that it is able to discern objects. In the context of the novel, the ...
doi:10.1111/j.2044-8295.1939.tb00948.x. Craik, K. J. W.; Vernon, M. D. (July 1941). "The nature of dark adaptation". British ... doi:10.1111/j.2044-8295.1941.tb01010.x. Craik, K. J. W.; Vernon, M. D. (January 1942). "Perception during dark adaptation". ... where he worked with Magdalen Dorothea Vernon and published papers with her about dark adaptation in 1941 and 1943. He was ... Intermittent control Craik, K. J. W. (January 1939). "The effect of adaptation upon visual acuity". British Journal of ...
Barlow, H.B. (1972). "Dark and Light Adaptation: Psychophysics.". Visual Psychophysics. New York: Springer-Verlag. ISBN 978-0- ... dark light, or brain gray, is the uniform dark gray background color that many people report seeing in the absence of light. ... The indistinguishability of dark events from photon responses supports this explanation, because rhodopsin is at the input of ... ISBN 978-0-12-078950-4. Baylor, D.A.; Matthews, G; Yau, K.-W. (1980). "Two components of electrical dark noise in toad retinal ...
Selig Hecht (1927). "The kinetics of dark adaptation". The Journal of General Physiology. 10 (5): 781-809. doi:10.1085/jgp.10.5 ...
Dark Heritage, a 1989 film adaptation. The Lurking Fear, a 1994 film adaptation. Bleeders, a 1997 film adaptation. The Lurking ... The Lurking Fear, a 2023 Tubi Original film adaptation. The story is referenced in Marauders (2016 film). "The Beast in the ... "a dark, lean man of about thirty-five, whose education, taste, intelligence, and temperament all seemed to mark him as one not ... A graphic novel adaptation written by Steven Philip Jones and drawn by Octavio Cariello was originally published in 1991 by ...
"Dark Places is Dark, but Doesn't Go Anyplace". "Dark Places review - Charlize Theron in a middling to dull thriller adaptation ... Official website Dark Places at IMDb Dark Places at Box Office Mojo Dark Places at Rotten Tomatoes Dark Places at Metacritic ( ... "Book Adaptation 'Dark Places' Starts Shooting". Thehollywoodnews.com. September 2, 2013. Retrieved April 16, 2015. Mike Fleming ... "Impressive cast in 'Dark Places' can't bring the heat". August 6, 2015. "'Dark Places' review: Lifetime-like melodrama". ...
These goggles helped with dark adaptation and could be worn at night so that flyers would immediately be ready for emergency ... Miles, W.R. (1943). "Red goggles for producing dark adaptation". Federal Proceedings of American Society for Experimental ... Miles, W.R. (1943). "Red goggles for producing dark adaptation". Federal Proceedings of American Society for Experimental ...
Once Upon a Time (1944) Road House (1948; story) The Dark Past (1948; adaptation) The Lady Gambles (1949; story) Once More, My ... He wrote one novel The Dark Side of Love, in 1974. He began screenwriting in 1944 with co-writing the screenplay for Strange ... His best-known work was on the screen adaptation of Tennessee Williams' A Streetcar Named Desire.' Saul co-wrote plays, ... adaptation of the play) Thunder on the Hill (1952) Affair in Trinidad (1952) Let's Do It Again (1953; producer) The Joker Is ...
McMurdo, M E; Gaskell, A (1991). "Dark adaptation and falls in the elderly". Gerontology. 37 (4): 221-4. doi:10.1159/000213264 ... placed for comfort or convenience in dark areas or areas that may become dark at certain times, such as at night or during an ... Rettner, Rachel (17 November 2010). "Avoiding Depression: Sleeping in Dark Room May Help". Live Science. Retrieved 23 June 2015 ... and only switch on when somebody is passing by in the dark. With the availability of low-cost LEDs, many different variants ...
An English adaptation is published by Dark Horse Comics. It was first published in individual volumes until volume 14. The ... 12". Dark Horse Comics. Retrieved February 10, 2011. 黒鷺死体宅配便 (13) (角川コミックス・エース 91-18). ASIN 404715380X. 黒鷺死体宅配便 (14) (角川コミックス・エ ... Dark Horse Comics > Profile > Kurosagi Corpse Delivery Service Vol. 6 TPB 黒鷺死体宅配便 (1) (角川コミックス・エース). ASIN 4047135275. "The ... 2". Dark Horse Comics. Retrieved December 14, 2009. 黒鷺
"Visual purple level and the course of dark adaptation". Nature. 173 (4398): 301-302. doi:10.1038/173301a0. PMID 13144746. S2CID ...
She starred in the novel adaptation Dark Places (2015). After the conclusion of Mad Men in 2015, she starred as a prostitute in ... "Dark Places". Dread Central. Retrieved July 7, 2014. Maas, Jennifer (November 29, 2018). "'Another Period' Canceled by Comedy ...
Kit, Borys (September 26, 2016). "Amandla Stenberg to Star in Fox's YA Adaptation of 'Darkest Minds' (Exclusive)". The ... Patten, Dominic (January 17, 2017). "Harris Dickinson To Star In Fox's YA Adaptation Of 'Darkest Minds'". Deadline Hollywood. ... Rought, Karen (February 19, 2017). "'The Darkest Minds' movie adaptation has found its Chubs". Hypable. Retrieved May 8, 2017. ... "The Darkest Minds (2018)- Financial Information". The Numbers. Retrieved 4 March 2021. "The Darkest Minds (2018)". Box Office ...
Hunt, R. W. G. (1 March 1952). "Light and Dark Adaptation and the Perception of Color*". Journal of the Optical Society of ...
"The Evil Dead #1 Movie Adaptation Dark Horse Comics". HeroesAssemble.com. Archived from the original on March 4, 2016. ... A video game adaptation of the same name was released for the Commodore 64 in 1984, as was a trilogy of survival horror games ... In January 2008, Dark Horse Comics began releasing a four-part monthly comic book mini-series, written by Mark Verheiden and ... In 2022, a video game adaptation of the series called Evil Dead: The Game was released. In 2021, heavy metal band Ice Nine ...
"Stage Review: Urban adaptation puts Alice into a darker Wonderland". Pittsburgh Post-Gazette. Retrieved September 13, 2006. " ... ", "The Picture of Dorian Gray" and a stage adaptation of The Butcher Brothers movie, The Hamiltons. In 2006, J.P. Patrick was ...
August also received story credit on Burton's Dark Shadows adaptation. August returned to Big Fish for a 2013 Broadway musical ... His adaptation became the 2003 Tim Burton film of the same name and earned August a 2003 BAFTA Award nomination for Best ... He reunited with Big Fish director Burton in 2005 for Charlie and the Chocolate Factory, an adaptation of Roald Dahl's classic ... In 2010, he partnered with game designer Jordan Mechner to pitch an adaptation of Mechner's Prince of Persia. August served as ...
He conducted several experiments involving the phenomenon of dark adaptation; namely the eye's ability to regain its ... This phenomenon is particularly evident in the dark. His earlier work dealt with zoological issues, such as studies of ... sensitivity in the dark after it had been exposed to bright lights. With ophthalmologist Richard Förster (1825-1902), he ...
Andreeva, Nellie (15 January 2020). "'The Dark Tower' Series Adaptation Not Going Forward at Amazon". Deadline Hollywood. "' ... in 2019 Hopkins directed the pilot episode for a potential The Dark Tower series for Amazon. However Amazon passed on the ... "STEPHEN HOPKINS DIRECTED THE PILOT FOR AMAZON'S THE DARK TOWER". JoBlo.com. ...
"BBC One commissions adaptation of Philip Pullman's His Dark Materials". BBC Media Centre. 3 November 2015. Archived from the ... Official website His Dark Materials at BBC Online His Dark Materials at IMDb His Dark Materials at epguides.com (Articles with ... White, Peter (12 September 2019). "'His Dark Materials': HBO & BBC Set Premiere Dates For Big-Budget Philip Pullman Adaptation ... Lawrence, Ben (15 October 2019). "His Dark Materials, episode 1, first-look review: a faithful adaptation full of strangeness ...
Kihara AH, de Castro LM, Moriscot AS, Hamassaki DE (May 2006). "Prolonged dark adaptation changes connexin expression in the ...
"Lateral interaction in the control of sensitivity during dark adaptation , WorldCat.org". www.worldcat.org. Retrieved 29 ... Hayhoe joined the University of California, San Diego for graduate research, where she studied how eyes adapt to dark light ...
"Jack Thorne opens up about His Dark Materials TV Series". "His Dark Materials: Behind the scenes of the TV adaptation". BBC. ... In November 2015, the BBC commissioned a television adaptation of His Dark Materials. The eight-part adaptation had a planned ... List of His Dark Materials and The Book of Dust characters Races and creatures in His Dark Materials Locations in His Dark ... BBC Radio 4 broadcast a radio play adaptation of His Dark Materials in 3 episodes, each lasting 2.5 hours. It was first ...
"Growth and Light/Dark Adaptation in Lysiosquillina Maculata (Stomatopoda, Crustacea)." Journal of Biological Research, vol. 81 ... Stomatopods are distinguished by their unique hunting adaptations, the most obvious being their second maxilliped modified into ... the distal half of which is dark in L. maculata but not in L. sulcata. A small artisanal fishery exists for this species. ...
Dark adaptation times vary from about fifteen minutes to overnight. Some researchers will only use pre-dawn values. Y(II) is a ... Fv/Fm tests whether or not plant stress affects photosystem II in a dark adapted state. Fv/Fm is the most used chlorophyll ... It compares the dark-adapted leaf pre-photosynthetic fluorescent state, called minimum fluorescence, or Fo, to maximum ... OJIP or OJIDP is a dark adapted chlorophyll fluorescence technique that is used for plant stress measurement. It has been found ...
"His Dark Materials: Behind the scenes of the TV adaptation". BBC. Retrieved 15 October 2019. "Logan's Dafne Keen: cutting her ... In 2019, Keen was cast in the lead role of Lyra Belacqua in the BBC/HBO television adaptation of the His Dark Materials trilogy ... "His Dark Materials: Season 1". Rotten Tomatoes. Retrieved 21 July 2020. Feinberg, Daniel (1 November 2019). "'His Dark ... In 2019, she began starring as Lyra Belacqua in the television series His Dark Materials, for which she was nominated for a ...
Dark adaptation gets weaker as people age, partially because the pupil of the eye cannot open as widely in older people. Color ... Dark Adaptation Threshold (DAT) is a vision test that measures the adjustment of the eye occurring under low levels of ... In order to perform this test, the child is asked to sit in the dark for a half-hour. This allows the eyes to be most sensitive ... Once the child can no longer see the spots, the dark adapted threshold is determined. The DAT test lasts for about 10 to 15 ...
... Vision Res. 1999 Nov;39(23):3975-82. doi: 10.1016/s0042-6989(99)00092-9. ... Dark adaptation functions were measured on 94 adults ranging in age from the 20s to the 80s to assess the rate of rod-mediated ... Results indicated that during human aging there is a dramatic slowing in rod-mediated dark adaptation that can be attributed to ... During the second component of the rod-mediated phase of dark adaptation, the rate of sensitivity recovery decreased 0.02 log ...
Download the citation for this article by clicking on one of the following citation managers:. ...
IDRIS Elba and Matthew McConaughey have been confirmed to star in the film adaptation of Stephen Kings Dark Tower. ... Idris Elba and Matthew McConaughey confirmed for Dark Tower adaptation. Story by Jack Foley ...
"A Haunting in Venice": a delightfully dark & gothic adaptation. September 16, 2023. By Louis Howley Leave a Comment ... The cinematography is very dark. There are a few well-lit rooms in the palazzo but there are several dark corners and spaces as ... I highly recommend you see this in a theater, as it is sometimes so dark that I do not know how this will translate to the ... I highly recommend you see this in a theater, as it is sometimes so dark that I do not know how this will translate to the ...
... series have been asking for a big screen adaptation for years. Universal Studios officially anno... ... Dark Tower Adaptation Faces Uncertain Future. Fans of Stephen Kings Dark Tower series have been asking for a big screen ... TagsAdaptation Akiva Goldsman Books Brian Grazer Canceled Dark Tower Javier Bardem Ron Howard Stephen King ... So in an era where Game of Thrones proves how a series is the only way that books like the Dark Tower could be done properly. ...
The Changeling review: Victor LaValles dark fairy tale gets a frustrating adaptation. ... Despite all of the aforementioned frustrations, The Changeling - the new Apple TV+ drama based on Victor LaValles dark fantasy ...
The Dark Tower will be adapted into a movie starring Idris Elba and Matthew McConaughey. ... the first book of Stephen Kings magnum opus Dark Tower series, and so, too, will begin its movie adaptation. Not only is the ... Previous attempts at an adaptation have been made, including by Ron Howard, who is producing, but the ingredients did not come ... Idris Elba and Matthew McConaughey to Star in Stephen Kings The Dark Tower. ...
Topic: "Dark Adaptation Functional Biomaker of Disease and Nutritional Status" and "Dark Adaptation Impairment in Patients with ... "Dark Adaptation Functional Biomaker of Disease and Nutritional Status" and "Dark Adaptation Impairment in Patients with AMD" ...
... spinoffs by other comics creators at Dark Horse, and a novel by Greg Rucka. The original hero, Hunter Rose, is most likely to ... features one of the most visually striking characters Dark Horse has ever published, and a story so popular it would not only ...
Film review: Fifty Shades Darker - second adaptation of E.L. James erotic novels as dull and cold as the first one ... Seven secrets from the set of Fifty Shades Darker, new E.L. James big-screen adaptation. ... 2. In Darker, Johnson pays tribute to her mother. Johnson may not let her parents, Don Johnson and Melanie Griffith, watch the ... Before filming Darker, Jamie Dornan tanned, increased his muscle mass and grew some scruff. "Shaving every day sucks," he ...
The train on new Stephen King adaptations left the station in 2017 after WBs reboot of IT became [...] ... New Adaptation of Stephen Kings The Dark Half Being Developed. The train on new Stephen King adaptations left the station in ... New Stephen King adaptations arent just limited to the big screen though as HBO will deliver their TV adaptation of The ... Since then, adaptations of Geralds Game and 1922 debuted on Netflix, plus a new Pet Sematary, IT: Chapter Two, Doctor Sleep, ...
... and the same was true after 2 h of dark adaptation (Figure 6C). At the age of 22 years, after 12 h of dark adaptation, a ... The technique applied for dark adaptation before examination in the dark-adapted state was conventional dense light-proof ... after prolonged dark adaptation. Full-field electroretinography and dark adaptometry at age 22 demonstrated reduced rod and ... of age after prolonged dark adaptation for 2 and 12 h on separate occasions. For the dark-adapted fundus photography, the ...
The term dark adaptation refers to the eyes increase in sensitivity in the dark. At night as I am getting into bed my light ... Our eyes begin to adjust to the dark in two steps, the initial rapid adaptation is caused by the cones adaptation, and the ... One of the last ideas of dark adaptation I have found to occur to me on numerous occasions is how the longer our eyes adapt to ... The first one is to measure the two stage dark adaptation curve that is caused by both the rods and cones working together. The ...
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"Dark Adaptation" by people in this website by year, and whether "Dark Adaptation" was a major or minor topic of these ... "Dark Adaptation" is a descriptor in the National Library of Medicines controlled vocabulary thesaurus, MeSH (Medical Subject ... Low aqueous solubility of 11-cis-retinal limits the rate of pigment formation and dark adaptation in salamander rods. J Gen ... Rhodopsin kinase and arrestin binding control the decay of photoactivated rhodopsin and dark adaptation of mouse rods. J Gen ...
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Posted in Action - Thriller, Film Reviews, Films, Superhero Tagged 2019, action, Dark Phoenix, Marvel, movie review, superhero ... Dark Phoenix character-driven story swamped by superhero fatigue. SR Staley June 12, 2019 ... Dark Phoenix limped into the box offices over its first weekend and seems destined to… ... Dark Phoenix limped into the box offices over its first weekend and seems destined to… ...
Home MacuLogix: Dark Adaptation and AMD "Dark Adaptation Has Always Been My Standard of Care," Says Pennsylvania OD ... the doctors at Kirman Eye schedule patients for dark adaptation testing. In the past, with only one dark adaptometer in a dark ... DARK ADAPTATION IS THE NEW NORMAL. Although the curriculum has likely evolved since Dr. Bahajak was a student, at the time she ... Practical Implementation of Dark Adaptation in Optometric Practice This 5th edition is jam-packed with great AMD information by ...
Dark Adaptation changes in highly myopic patients. European Journal of Ophthalmology. July 2018. ...
Improvement of dark adaptation. A full day at the beach or on the ski slopes on a sunny day (without dark sunglasses) can ... impair dark adaptation for more than 2 days. Thus, dark sunglasses are recommended for prolonged periods in bright sun. ... In fact, dark sunglasses reduce light levels striking the eye on a bright, sunny day to the range of 2000-6000 foot-lamberts. ... Almost all dark sunglasses absorb most incident UV light. The same is true for certain coated clear-glass lenses and clear ...
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Strong storylines and layered characters lift Dark Phoenix above standard superhero movies ... Strong storylines and characters lift Dark Phoenix. SR Staley June 12, 2019 Posted in Action - Thriller, Characters development ... Dark Phoenix limped into the box offices over its first weekend and seems destined to be a big-ticket flop. Part of the movies ... Dark side tempts. This Marvel movie installment puts Jean Grey, aka Phoenix (Sophie Turner) at the center of the plot. Jean is ...
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What really happened to this fateful flight and the 107 souls on board? Join us as we unravel the threads of this dark mystery ... What really happened to this fateful flight and the 107 souls on board? Join us as we unravel the threads of this dark mystery ...
David Slade has signed on to direct the feature film adaptation of Norman Partridges Halloween horror novel Dark Harvest! ... David Slade to Direct Halloween Horror Adaptation Dark Harvest September 10, 2019. April 7, 2020. Matt Artz 0 Comments Dark ... David Slade will direct the feature film adaptation of Norman Partridges Halloween horror novel Dark Harvest, bringing a new ... Dark Harvest Trailer Tells Halloween 1963 Legend of Sawtooth Jack September 13, 2023. September 14, 2023. Matt Artz 0 ...
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  • Results indicated that during human aging there is a dramatic slowing in rod-mediated dark adaptation that can be attributed to delayed rhodopsin regeneration. (nih.gov)
  • During the second component of the rod-mediated phase of dark adaptation, the rate of sensitivity recovery decreased 0.02 log unit/min per decade, and the time constant of rhodopsin regeneration increased 8.4 s/decade. (nih.gov)
  • Rhodopsin kinase and arrestin binding control the decay of photoactivated rhodopsin and dark adaptation of mouse rods. (musc.edu)
  • Red light works best because it is less efficient than white light at breaking down the iodopsin and rhodopsin that allow your eye to see in the dark. (telescope.com)
  • In light adaptation, rhodopsin is activated (ie, 11- cis -retinal is photoisomerized), and the attached G-protein (transducin) is also activated. (medscape.com)
  • IDRIS Elba and Matthew McConaughey have been confirmed to star in the film adaptation of Stephen King's Dark Tower . (indielondon.co.uk)
  • Fans of Stephen King's 'Dark Tower' series have been asking for a big screen adaptation for years. (highdefdigest.com)
  • So begins The Gunslinger , the first book of Stephen King's magnum opus Dark Tower series, and so, too, will begin its movie adaptation. (time.com)
  • The Dark Half is inspired by King's own time writing novels under a pseudonym. (comicbook.com)
  • The Dark Tower is slated for release on Jan. 13, 2017. (time.com)
  • Mike Flanagan has made it clear he wants to bring The Dark Tower back to our screens after the 2017 movie flopped, and he's now earned the thumbs up from author Stephen King. (sffgazette.com)
  • Not only is the long awaited adaptation underway, with plans to begin filming in South Africa next month, but its two central characters have been cast, as well: Idris Elba will star as gunslinger Roland Deschain, and Matthew McConaughey will play the mysterious man in black, Entertainment Weekly reported Tuesday morning. (time.com)
  • The major function of dark (gray, green, or brown) sunglasses is to allow the retina to remain at its normal level of contrast sensitivity. (aao.org)
  • However, a GLE-induced loss/dysfunction of DA ACs during development could increase the number of rods and bipolar cells since DA helps regulate neuronal proliferation, whereas during adulthood it could produce ERG supernormality as well as altered circadian rhythms, dark/light adaptation and spatial contrast sensitivity. (cdc.gov)
  • The effects of ageing on selected visual functions: Dark adaptation, visual acuity, stereopsis and brightness contrast. (bvsalud.org)
  • New Stephen King adaptations aren't just limited to the big screen though as HBO will deliver their TV adaptation of The Outsider early next year. (comicbook.com)
  • Dark adaptation functions were measured on 94 adults ranging in age from the 20s to the 80s to assess the rate of rod-mediated sensitivity recovery after exposure to a 98% bleach. (nih.gov)
  • The term dark adaptation refer's to the eye's increase in sensitivity in the dark. (perceptionsense.com)
  • The next experiment measures the cones sensitivity levels in dark adaptation, and the same with the rods. (perceptionsense.com)
  • From this experiment researchers noticed that sensitivity to the dark increases in two phases. (perceptionsense.com)
  • Much like the experiment done to test the whole process of dark adaptation, reseahcers use the same experiment with some tweaks to test the cones and rods sensitivity levels separately. (perceptionsense.com)
  • As you can see by the image above the cones are sensitive at the beginning then level off because you will see with the experiment done to test the rod's sensitivity the rods begin to take over the dark adaptation curve in the second phase. (perceptionsense.com)
  • The sensitivity of the eye to light is increased during dark adaptation. (musc.edu)
  • At the end of a half-hour or so the eye has achieved almost all of its dark sensitivity, with a small increase continuing until about 1 hour or so. (telescope.com)
  • Universal's plan for 'The Dark Tower' was to include Imagine Entertainment and NBC. (highdefdigest.com)
  • On Friday, THR reported that 'The Dark Tower' would remain with Universal and that a compromise was in the works. (highdefdigest.com)
  • What do you 'Dark Tower' fans out there make of this? (highdefdigest.com)
  • 2017's The Dark Tower had the potential to be a great movie and was supposed to be the beginning of a new franchise that would tell stories set in that world both in theaters and on streaming. (sffgazette.com)
  • It's important to note that no network or streaming service is currently attached to The Dark Tower . (sffgazette.com)
  • "[My Dark Tower adaptation] couldn't be more different [from the movie]," Flanagan previously explained. (sffgazette.com)
  • That was the wrong approach to the material, kind've across the board, and it was such the wrong approach that I think it kind've salted the earth for anyone else who wanted to plant something under the Dark Tower banner for who knows how long. (sffgazette.com)
  • Stay tuned for updated on The Dark Tower as we have them. (sffgazette.com)
  • Clinical examination, kinetic Goldmann perimetry, dark adaptometry, fundus autofluorescence photography, spectral domain optical coherence tomography (SD-OCT), full-field electroretinography (ffERG), and multifocal electroretinography (mfERG) were performed. (molvis.org)
  • Fundus autofluorescence was unremarkable and did not change after prolonged dark adaptation. (molvis.org)
  • Dark adaptation before fundus photography may enable the detection of a tapetal-like reflex where it is otherwise invisible. (molvis.org)
  • Patients with fundus albipunctatus have poor dark adaptation but may have normal results after 3-4 hours of adaptation. (medscape.com)
  • The circadian rhythm can be entrained by light and dark. (cdc.gov)
  • Based on age, family history, or other concerns, the doctors at Kirman Eye schedule patients for dark adaptation testing. (womeninoptometry.com)
  • In the past, with only one dark adaptometer in a dark room, these patients would need to be rescheduled. (womeninoptometry.com)
  • In this report, we describe a female carrier of XLRP where the tapetal-like reflex was clearly present after light exposure at 16 years of age, but much less so at 22 years of age when it did, however, reappear after prolonged dark adaptation and was attenuated by renewed light exposure. (molvis.org)
  • Most dark sunglasses absorb 70%-80% of the incident light of all wavelengths. (aao.org)
  • This button allows you to modify the site theme for Dark Mode or Light Mode. (sffgazette.com)
  • But when in the dark the concentration of these chemicals begins to grow and the rod cells and cone cells in the retina become more and more light sensitive. (telescope.com)
  • Any amount of light will reduce your dark adaptation, so get away from street lamps, porch lights, car headlights, and urban skyglow. (telescope.com)
  • Exposure to intense light can hamper your dark-adaptation for a long time! (telescope.com)
  • If you are in a light-polluted location consider wearing dark glasses or special red night-vision goggles at all times except when looking through the eyepiece. (telescope.com)
  • In particular, they have delayed dark adaptation, which means they have trouble adapting from bright light to dark conditions, such as when driving into a dark tunnel on a sunny day. (medlineplus.gov)
  • In the absence of light (ie, dark adaptation), a constant influx of Na + ions (dark current) occurs through the outer segment membrane of photoreceptors, giving rise to a resting membrane potential of about -40 mV. (medscape.com)
  • A light flash decreases the dark current and hyperpolarizes the photoreceptors relative to the dark state, reducing the amount of inhibitory neurotransmitters released onto the bipolar cell. (medscape.com)
  • Normally, melatonin production is 5 to 20 times higher at night in the dark than during the day, but this normal night-time elevation is suppressed by exposure to artificial light. (cdc.gov)
  • Our eyes begin to adjust to the dark in two steps, the initial rapid adaptation is caused by the cones adaptation, and the second is caused by the rods adaptation. (perceptionsense.com)
  • The first one is to measure the two stage dark adaptation curve that is caused by both the rods and cones working together. (perceptionsense.com)
  • In the rod experiment the reseachers had to ask an observer who does not have cones so they could determine how quickly only the rods adapt to the dark. (perceptionsense.com)
  • Low aqueous solubility of 11-cis-retinal limits the rate of pigment formation and dark adaptation in salamander rods. (musc.edu)
  • But the rods are not color sensitive, which is why in the dark you can see only shades of gray. (telescope.com)
  • A full day at the beach or on the ski slopes on a sunny day (without dark sunglasses) can impair dark adaptation for more than 2 days. (aao.org)
  • Dark Adaptation Threshold (DAT) is a vision test that measures the adjustment of the eye occurring under low levels of illumination. (wikipedia.org)
  • Once the child can no longer see the spots, the dark adapted threshold is determined. (wikipedia.org)
  • Dark-adaptation threshold should be tested. (medscape.com)
  • One of the last ideas of dark adaptation I have found to occur to me on numerous occasions is how the longer our eyes' adapt to the dark when we walk out into a lit room our eyes are extremely sensitive right away and need to adjust just like they do in the dark. (perceptionsense.com)
  • It often takes hours for adaptation to occur. (medlineplus.gov)
  • This severance of a body and its soul, known as zombification, is thought to occur when a sorcerer, or boko, performs a combination of dark magic spells on a person to kill, enslave, or inflict illness upon him. (cdc.gov)
  • A special sneak peek at Dark Horse's highly-anticipated comic book adaptation of the original Star Wars script! (starwars.com)
  • The Star Wars will come to life via an eight-issue comic book miniseries from Dark Horse, written by J.W. Rinzler and illustrated by Mike Mayhew, with issue #1 hitting comic book shops on September 4. (starwars.com)
  • Frank Darabont's award- winning adaptation of The Walking Dead comic books has proven that zombies maintain thematic prominence even when serving as the backdrop to a character-driven television drama. (cdc.gov)
  • Abnormal visual adaptation to darkness, dry skin, dry hair, broken fingernails, and decreased resistance to infections are among the first signs of VAD. (medscape.com)
  • This phenomenon is called dark adaptation , and it is crucial for visual astronomy, especially for observation of faint objects, such as galaxies and nebulas. (telescope.com)
  • Find iPhone 11 Pro MAX in purses, backpacks, or any dark situation! (adaptationla.com)
  • These aging-related changes in rod-mediated dark adaptation may contribute to night vision problems commonly experienced by the elderly. (nih.gov)
  • This "Woyzeck" is, true to LaBute's (and Büchner's) vision, transfixing, in a dark and disturbing way, imbuing the tale of the murderous soldier Woyzeck with the solemn and steady inevitability of a Greek tragedy. (njarts.net)
  • Vitamin A is essential for vision (especially dark adaptation), immune response, bone growth, reproduction, the maintenance of the surface linings of the eyes, epithelial cell growth and repair, and the epithelial integrity of the respiratory, urinary, and intestinal tracts. (medscape.com)
  • When your eye is fully dark adapted, most of your night vision comes from the rod cells in the retina. (telescope.com)
  • So now that you know how night vision works, here's how to maximize your ability to see in the dark. (telescope.com)
  • Actor Johnny Depp filming new Tim Burton movie Dark Shadows on location on a remote beach in South Devon. (atbreak.com)
  • The Dark Half was previously adapted into a feature film in 1993, written and directed by previous King collaborator George A. Romero. (comicbook.com)
  • The bright colors you see in pictures of nebulas and galaxies are typically only visible in photographs (film being much more sensitive to colors than a dark-adapted eye). (telescope.com)
  • Thus, dark sunglasses are recommended for prolonged periods in bright sun. (aao.org)
  • After a little time the images outlines become more distinct and the dark room doesn't look so dark anymore. (perceptionsense.com)
  • Although the curriculum has likely evolved since Dr. Bahajak was a student, at the time she says dark adaptation was not as heavily emphasized as it is now in most of the optometric magazines and in optometric CE programs. (womeninoptometry.com)
  • In 2020, Studio MAPPA began producing an anime of the series, directed by Sunghoo Park, and, frankly, it was only a matter of time before an adaptation was made for theaters. (elementsofmadness.com)
  • To report changes in the tapetal-like reflex in a female carrier of RPGR ORF15 c.3395delA X-linked retinitis pigmentosa (XLRP) between examinations at 16 and 22 years of age, and to report the observation that the tapetal-like reflex faded due to exposure to daylight and reappeared with prolonged dark adaptation at 22 years of age. (molvis.org)
  • Since then, adaptations of Gerald's Game and 1922 debuted on Netflix, plus a new Pet Sematary , IT: Chapter Two , Doctor Sleep , and In the Tall Grass , with adaptations of 'Salem's Lot , The Long Walk , and From a Buick 8 all in development. (comicbook.com)
  • Previous attempts at an adaptation have been made, including by Ron Howard, who is producing, but the ingredients did not come together until now. (time.com)
  • I didn't even realize it until after I had made this recent batch of cookies with a few staple mix-ins, but these cookies are a pretty good representation of what I like in a dessert: rich dark chocolate, flavorful coconut, and sweet bold fruit. (aasquaredblog.com)
  • The topic I have always found interesting is our eye's ability to adapt to seeing in a dark room. (perceptionsense.com)
  • This graph shows the total number of publications written about "Dark Adaptation" by people in this website by year, and whether "Dark Adaptation" was a major or minor topic of these publications. (musc.edu)
  • These cookies are just sweet enough with a hint of salt, and some spice from cinnamon gets amped up with my favorite flavor combo of dark chocolate, coconut, and dried cherries. (aasquaredblog.com)
  • after 3-4 hours of dark adaptation, ERG findings may be normal. (medscape.com)
  • Ahead of its release, King called The Outsider one of the best adaptations of his work. (comicbook.com)
  • This is because the comparison groups are necessarily day-workers who live in modern societies and who certainly do not go to dark at sunset, and who may also often start the work day before sunrise. (cdc.gov)
  • This study also showed that when workers were ranked on their sleep to work urinary 6-sulphatoxymelatonin ratio, this ratio was a better predictor of adaptation than shift worked. (cdc.gov)
  • Dark adaptation gets weaker as people age, partially because the pupil of the eye cannot open as widely in older people. (wikipedia.org)
  • Below are the most recent publications written about "Dark Adaptation" by people in Profiles. (musc.edu)
  • Deep learning methods have the potential to accurately identify images containing substructure, and differentiate WIMP particle dark matter from other well motivated models, including vortex substructure of dark matter condensates and superfluids. (ml4sci.org)
  • This two step process is referred to as the dark adaptation curve. (perceptionsense.com)
  • Recently after reading about dark adaptation I've began to pay more attention when I go to shut my lights off at night to watch for the gradual two step process of dark adaptation. (perceptionsense.com)
  • Zack Snyder has no current plans to return to DC, but says an adaptation of Dark Knight Returns is. (yahoo.com)
  • approximately' means that under constant dark conditions the rhythm is typically a little longer than 24 hours. (cdc.gov)
  • Dark gray indicates the putative fusion peptide ( 32 ). (cdc.gov)
  • Full-field electroretinography and dark adaptometry at age 22 demonstrated reduced rod and cone function compared to at age 16. (molvis.org)