To see the other types of publications on this topic, follow the link: Eye's response to light.
Journal articles on the topic 'Eye's response to light'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Eye's response to light.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Batra, R., and R. B. Barlow. "Efferent control of temporal response properties of the Limulus lateral eye." Journal of General Physiology 95, no. 2 (February 1, 1990): 229–44. http://dx.doi.org/10.1085/jgp.95.2.229.
Full textAbstract:
The sensitivity of the Limulus lateral eye exhibits a pronounced circadian rhythm. At night a circadian oscillator in the brain activates efferent fibers in the optic nerve, inducing multiple changes in the physiological and anatomical characteristics of retinal cells. These changes increase the sensitivity of the retina by about five orders of magnitude. We investigated whether this increase in retinal sensitivity is accompanied by changes in the ability of the retina to process temporal information. We measured the frequency transfer characteristic (FTC) of single receptors (ommatidia) by recording the response of their optic nerve fibers to sinusoidally modulated light. We first measured the FTC in the less sensitive daytime state and then after converting the retina to the more sensitive nighttime state by electrical stimulation of the efferent fibers. The activation of these fibers shifted the peak of the FTC to lower frequencies and reduced the slope of the low-frequency limb. These changes reduce the eye's ability to detect rapid changes in light intensity but enhance its ability to detect dim flashes of light. Apparently Limulus sacrifices temporal resolution for increased visual sensitivity at night.
2
Oland, L. A., and A. E. Stuart. "Pattern of convergence of the receptors of the barnacle's three ocelli onto second-order cells." Journal of Neurophysiology 55, no. 5 (May 1, 1986): 882–95. http://dx.doi.org/10.1152/jn.1986.55.5.882.
Full textAbstract:
The giant barnacle, Balanus nubilus, has three simple eyes, two lateral and one median. We have studied the convergence of the receptors of these ocelli by recording from the second-order cell (I-cell) and from the receptors' terminals. The I-cell's responses to illumination of the median and lateral eyes are similar in shape, dynamic range, and reversal potential, but the response to lateral input has a longer latency, a slower rise time, and a smaller amplitude. These differences primarily reflect the different voltage changes in the terminals of the decrementally conducting median and lateral receptors. Simultaneous recordings from the terminals of median and lateral receptors showed that the responses to light recorded in lateral terminals had a longer latency, a slower rise time, and smaller amplitude than signals in median terminals. The differences in the I-cell's responses to median and lateral input were essentially eliminated by stimulating the median and lateral ocellar nerves with extracellular suction electrodes positioned at equal distances from the receptors' terminals. The similarity of the I-cell's responses to median and lateral input suggests that lateral photoreceptors, like median receptors, contact the I-cell directly. No evidence was found for interaction between median and lateral receptors. Simultaneous fills of median and lateral receptors with cobalt showed minimal overlap between their terminal arbors. No voltage change was detected in the second receptor when the voltage in the first was changed with current pulses or when action potentials were elicited in the presence of tetraethylammonium ions. The absence of a detectable response in the terminals of one eye's receptors when the receptors of the other eye were stimulated with current or light suggests that there is no feedback from the I-cell to the receptors. Simultaneous illumination of the median and lateral eyes produced responses in the I-cell expected from two independent inputs. The first synaptic stage of the visual pathway in the barnacle is thus unusually simple, consisting of a small number of electrically isolated photoreceptors converging upon the same pair of second-order cells with no feedback interaction.
3
Passaglia, Christopher L., Frederick A. Dodge, and Robert B. Barlow. "Cell-Based Model of the Limulus Lateral Eye." Journal of Neurophysiology 80, no. 4 (October 1, 1998): 1800–1815. http://dx.doi.org/10.1152/jn.1998.80.4.1800.
Full textAbstract:
Passaglia, Christopher L., Frederick A. Dodge, and Robert B. Barlow. Cell-based model of the Limulus lateral eye. J. Neurophysiol. 80: 1800–1815, 1998. We present a cell-based model of the Limulus lateral eye that computes the eye's input to the brain in response to any specified scene. Based on the results of extensive physiological studies, the model simulates the optical sampling of visual space by the array of retinal receptors (ommatidia), the transduction of light into receptor potentials, the integration of excitatory and inhibitory signals into generator potentials, and the conversion of generator potentials into trains of optic nerve impulses. By simulating these processes at the cellular level, model ommatidia can reproduce response variability resulting from noise inherent in the stimulus and the eye itself, and they can adapt to changes in light intensity over a wide operating range. Programmed with these realistic properties, the model eye computes the simultaneous activity of its ensemble of optic nerve fibers, allowing us to explore the retinal code that mediates the visually guided behavior of the animal in its natural habitat. We assess the accuracy of model predictions by comparing the response recorded from a single optic nerve fiber to that computed by the model for the corresponding receptor. Correlation coefficients between recorded and computed responses were typically >95% under laboratory conditions. Parametric analyses of the model together with optic nerve recordings show that animal-to-animal variation in the optical and neural properties of the eye do not alter significantly its response to objects having the size and speed of horseshoe crabs. The eye appears robustly designed for encoding behaviorally important visual stimuli. Simulations with the cell-based model provide insights about the design of the Limulus eye and its encoding of the animal's visual world.
4
Oh, J. K., D. L. Bohnsack, J. B. Troy, and Ch Enroth-Cugell. "The cat's pupillary light response under urethane anesthesia." Visual Neuroscience 12, no. 2 (March 1995): 281–84. http://dx.doi.org/10.1017/s0952523800007963.
Full textAbstract:
AbstractPupillary area was measured in urethane-anesthetized cats as a function of retinal illuminance. When appropriate corrections are made for differences in experimental procedures, it was found that the pupillary response of the urethane-anesthetized cat's eyes to light was basically unchanged from that of the alert behaving cat. This preparation may therefore be a very satisfactory one in which to study the pupillary response pathway in a higher mammal.
5
GRINNELL, A. D., P. M. NARINS, F. T. AWBREY, W. M. HAMNER, and P. P. HAMNER. "Eye/Photophore Coordination and Light-following in Krill, Euphausia Superba." Journal of Experimental Biology 134, no. 1 (January 1, 1988): 61–77. http://dx.doi.org/10.1242/jeb.134.1.61.
Full textAbstract:
Eight of the 10 photophores of the Antarctic krill, Euphausia superba, are located at the ends of muscular stalks and exhibit coordinated orientation responses to incident white light; light emitted from the photophores is directed away from the incident light. Moreover, eye rotation occurs synchronously with photophore movement. Immobilization of one or both eyes eliminated the photophore light-following response in 40% of the trials, but in the remaining 60%, photophores continued to exhibit oriented, but less stable responses. In the presence of a stationary light source the eyes could be passively rotated without affecting photophore position. Furthermore, eye removal or covering the head with an opaque hood eliminated coordinated photophore movement. We conclude that vision is necessary for light-following responses by the photophores. In addition, the control signal for that movement is CNS-derived, may occur spontaneously or may be lightinduced, and appears to be accompanied by a parallel signal governing eye rotation. Subtle differences in photophore response when krill were oriented other than horizontally imply that krill may have a gravity sense that could help them orient in darkness.
6
Roberts, Adam T., Stephanie K. Medley, Don A. Gregory, and Nilesh B. Dhote. "Simplified estimation of the eye’s response to flashing light-emitting diodes." Journal of Biomedical Optics 20, no. 6 (June 19, 2015): 065005. http://dx.doi.org/10.1117/1.jbo.20.6.065005.
Full text
7
MacKinnon, Barbara M. "Response of the Copepodid Larvae of Caligus elongatus to Light, and the Ultrastructure of the Eyes." Canadian Journal of Fisheries and Aquatic Sciences 50, no. 4 (April 1, 1993): 793–99. http://dx.doi.org/10.1139/f93-092.
Full textAbstract:
The copepodid larvae of Caligus elongatus are positively attracted to light over increasing light intensities using a vertical light source of 400 lx placed 25 cm from the larvae. The larvae are not attracted to the light source from a distance of 50 cm. Larvae in the dark did not migrate in any one particular direction. The copepodid larvae, examined ultrastructurally, have paired eyes with a triangular lensless third eye located below and between the two main eyes. The two main eyes each have an anterolaterally directed dorsal lens contained within a lens cell. Six rhabdomeric sensory cells and cup-shaped platelet sensory cells are contained by a pigment granule cup-shaped cell in each eye. Nerve axons from the sensory cells exit the eyes posterioventrally.
8
Ariel, M., and A. F. Rosenberg. "Effects of synaptic drugs on turtle optokinetic nystagmus and the spike responses of the basal optic nucleus." Visual Neuroscience 7, no. 5 (November 1991): 431–40. http://dx.doi.org/10.1017/s095252380000972x.
Full textAbstract:
AbstractBehavioral and electrophysiological measures were used to elucidate the retinal modulation of oculomotor control in the turtle. Eye movements were recorded following intravitreal applications of 2-amino-4-phosphonobutyrate (APB) and the GABA antagonists picrotoxin and bicuculline. Visual responses of single basal optic nucleus (BON) neurons of the accessory optic system were studied in parallel experiments. The effectiveness of APB, a glutamate analog thought to act selectively on the retinal ON pathway, was assessed independently by recording electroretinograms or ganglion cell activity.Injections of APB into the turtle's eye reduced or blocked the injected eye's ability to drive horizontal optokinetic nystagmus, as also observed in rabbit and cat (Knapp et al., 1988; Yucel et al., 1989). Single-unit recordings from the BON during APB superfusion (50–200 μM APB) of the contralateral retina demonstrated that these cells, which are direction-sensitive and respond to the offset of light flashes, have their responses to moving stimuli blocked by APB.During the APB effect, GABA antagonists were applied to the same eye. Although moderate doses of APB were sufficient to block optokinetic or BON light responses, the addition of GABA blockers still elicited a spontaneous temporal-to-nasal nystagmus (Ariel, 1989) or visually responsive yet direction-insensitive responses from BON cells (Schuerger et al., 1990). These results are discussed in terms of the retinal output to pathways involved in oculomotor control of optokinetic nystagmus.
9
Dacke, Marie, Thuy A. Doan, and David C. O’Carroll. "Polarized light detection in spiders." Journal of Experimental Biology 204, no. 14 (July 15, 2001): 2481–90. http://dx.doi.org/10.1242/jeb.204.14.2481.
Full textAbstract:
SUMMARYWe describe here the detection of polarized light by the simple eyes of spiders. Using behavioural, morphological, electrophysiological and optical studies, we show that spiders have evolved two different mechanisms to resolve the e-vector of light. Wolf spiders (Lycosidae), are able to turn in response to rotation of a polarized pattern at the zenith of their visual fields, and we also describe a strip in the ventral retina of the principal (anterio-median) eyes that views this location and has receptors tiered into two layers. This provides each pair of receptors with a similar optical solution to that provided by the ‘dorsal rim area’ of the insect compound eye. In contrast, gnaphosid spiders have evolved a pair of lensless secondary eyes for the detection of polarized light. These two eyes, each sensitive to orthogonal directions of polarization, are perfectly designed to integrate signals from the larger part of the sky and cooperate to analyse the polarization of light. Built-in polarizers help to improve signal purity. Similar organisation in the eyes of several other spider families suggests that these two mechanisms are not restricted to only a few families.
10
Chiou, Tsyr-Huei, and Ching-Wen Wang. "Neural processing of linearly and circularly polarized light signal in a mantis shrimp Haptosquilla pulchella." Journal of Experimental Biology 223, no. 22 (October 23, 2020): jeb219832. http://dx.doi.org/10.1242/jeb.219832.
Full textAbstract:
ABSTRACTStomatopods, or mantis shrimp, are the only animal group known to possess circular polarization vision along with linear polarization vision. By using the rhabdomere of a distally located photoreceptor as a wave retarder, the eyes of mantis shrimp are able to convert circularly polarized light into linearly polarized light. As a result, their circular polarization vision is based on the linearly polarized light-sensitive photoreceptors commonly found in many arthropods. To investigate how linearly and circularly polarized light signals might be processed, we presented a dynamic polarized light stimulus while recording from photoreceptors or lamina neurons in intact mantis shrimp Haptosquilla pulchella. The results indicate that all the circularly polarized light-sensitive photoreceptors also showed differential responses to the changing e-vector angle of linearly polarized light. When stimulated with linearly polarized light of varying e-vector angle, most photoreceptors produced a concordant sinusoidal response. In contrast, some lamina neurons doubled the response frequency in reacting to linearly polarized light. These responses resembled a rectified sum of two-channel linear polarization-sensitive photoreceptors, indicating that polarization visual signals are processed at or before the first optic lobe. Noticeably, within the lamina, there was one type of neuron that showed a steady depolarization response to all stimuli except right-handed circularly polarized light. Together, our findings suggest that, between the photoreceptors and lamina neurons, linearly and circularly polarized light may be processed in parallel and differently from one another.
11
Miller, Hayley V., Alexandra C. N. Kingston, Yakir L. Gagnon, and Daniel I. Speiser. "The mirror-based eyes of scallops demonstrate a light-evoked pupillary response." Current Biology 29, no. 9 (May 2019): R313—R314. http://dx.doi.org/10.1016/j.cub.2019.03.053.
Full text
12
Barth, F. G., T. Nakagawa, and E. Eguchi. "VISION IN THE CTENID SPIDER CUPIENNIUS SALEI: SPECTRAL RANGE AND ABSOLUTE SENSITIVITY." Journal of Experimental Biology 181, no. 1 (August 1, 1993): 63–80. http://dx.doi.org/10.1242/jeb.181.1.63.
Full textAbstract:
Electroretinograms were recorded from all eyes of the wandering spider Cupiennius salei (Ctenidae) and were found to be simple cornea-negative potential differences with amplitudes of up to 10 mV. In both the principal eyes and all of the secondary eyes, the spectral response curves show a prominent green peak at 520 or 540 nm and a shoulder in the ultraviolet between 340 and 380 nm. The largest response in the ultraviolet measures between 65 % and 80 % of the green peak. Selective chromatic adaptation to either green or ultraviolet monochromatic light does not change these relative response levels and fails to indicate the presence of more than one spectral type of receptor. In the range 450–500 nm, however, the Dartnall curve clearly deviates from the spectral sensitivity (SS) curve. Since the SS curves of all eyes have a small shoulder in the blue at 480 nm, the existence of two or even three visual pigments is a possibility. Intensity curves were determined with white and monochromatic light. For white light, absolute corneal illuminance thresholds were clearly below 0.01 lx. For monochromatic light stimuli, a corneal illuminance of approximately 3×1012 photons cm-2 s-1 is needed to elicit a half-maximal response. At threshold, the equivalent value is 3×109 photons cm-2 s-1, which corresponds to a retinal illuminance of 5.9×109 photons cm-2 s-1. Consequently, Cupiennius salei should be able to use its visual sense not only shortly after sundown but also under much poorer light conditions, such as those provided by moonlight. The log-linear response range of all eyes covers a stimulus intensity range of 4 log units. The sensitivity of the principal eyes increases by up to 0.81 log units at night as compared with daytime. The chromophore of the visual pigment of all eyes is 11- cis retinal.
13
van Kleef, Joshua, Andrew Charles James, and Gert Stange. "A Spatiotemporal White Noise Analysis of Photoreceptor Responses to UV and Green Light in the Dragonfly Median Ocellus." Journal of General Physiology 126, no. 5 (October 31, 2005): 481–97. http://dx.doi.org/10.1085/jgp.200509319.
Full textAbstract:
Adult dragonflies augment their compound eyes with three simple eyes known as the dorsal ocelli. While the ocellar system is known to mediate stabilizing head reflexes during flight, the ability of the ocellar retina to dynamically resolve the environment is unknown. For the first time, we directly measured the angular sensitivities of the photoreceptors of the dragonfly median (middle) ocellus. We performed a second-order Wiener Kernel analysis of intracellular recordings of light-adapted photoreceptors. These were stimulated with one-dimensional horizontal or vertical patterns of concurrent UV and green light with different contrast levels and at different ambient temperatures. The photoreceptors were found to have anisotropic receptive fields with vertical and horizontal acceptance angles of 15° and 28°, respectively. The first-order (linear) temporal kernels contained significant undershoots whose amplitudes are invariant under changes in the contrast of the stimulus but significantly reduced at higher temperatures. The second-order kernels showed evidence of two distinct nonlinear components: a fast acting self-facilitation, which is dominant in the UV, followed by delayed self- and cross-inhibition of UV and green light responses. No facilitatory interactions between the UV and green light were found, indicating that facilitation of the green and UV responses occurs in isolated compartments. Inhibition between UV and green stimuli was present, indicating that inhibition occurs at a common point in the UV and green response pathways. We present a nonlinear cascade model (NLN) with initial stages consisting of separate UV and green pathways. Each pathway contains a fast facilitating nonlinearity coupled to a linear response. The linear response is described by an extended log-normal model, accounting for the phasic component. The final nonlinearity is composed of self-inhibition in the UV and green pathways and inhibition between these pathways. The model can largely predict the response of the photoreceptors to UV and green light.
14
Swafford, Andrew J. M., and Todd H. Oakley. "Light-induced stress as a primary evolutionary driver of eye origins." Integrative and Comparative Biology 59, no. 4 (September 20, 2019): 739–50. http://dx.doi.org/10.1093/icb/icz064.
Full textAbstract:
Abstract Eyes are quintessential complex traits and our understanding of their evolution guides models of trait evolution in general. A long-standing account of eye evolution argues natural selection favors morphological variations that allow increased functionality for sensing light. While certainly true in part, this focus on visual performance does not entirely explain why diffuse photosensitivity persists even after eyes evolve, or why eyes evolved many times, each time using similar building blocks. Here, we briefly review a vast literature indicating most genetic components of eyes historically responded to stress caused directly by light, including ultraviolet damage of DNA, oxidative stress, and production of aldehydes. We propose light-induced stress had a direct and prominent role in the evolution of eyes by bringing together genes to repair and prevent damage from light-stress, both before and during the evolution of eyes themselves. Stress-repair and stress-prevention genes were perhaps originally deployed as plastic responses to light and/or as beneficial mutations genetically driving expression where light was prominent. These stress-response genes sense, shield, and refract light but only as reactions to ongoing light stress. Once under regulatory-genetic control, they could be expressed before light stress appeared, evolve as a module, and be influenced by natural selection to increase functionality for sensing light, ultimately leading to complex eyes and behaviors. Recognizing the potentially prominent role of stress in eye evolution invites discussions of plasticity and assimilation and provides a hypothesis for why similar genes are repeatedly used in convergent eyes. Broadening the drivers of eye evolution encourages consideration of multi-faceted mechanisms of plasticity/assimilation and mutation/selection for complex novelties and innovations in general.
15
NALBACH, H. O., P. THIER, and D. VARJÚ. "Light-Dependent Eye Coupling during the Optokinetic Response of the Crab Carcinus Maenas (L.)." Journal of Experimental Biology 119, no. 1 (November 1, 1985): 103–14. http://dx.doi.org/10.1242/jeb.119.1.103.
Full textAbstract:
1. The movements of both distal eye stalks in the horizontal plane, elicited by optokinetic stimuli, have been recorded simultaneously. 2. A panorama was split into two separate halves and was either oscillated around the animal in a sinusoidal fashion or displaced in a stepwise manner. Both eyes could be stimulated independently. 3. The stimuli on both sides differed either (a) in the illumination, or (b) in the total amount of light impinging upon the eyes or (c) in the relative phase of the sinusoidal stimuli to either eye. 4. As the illumination decreases the optokinetic response weakens. 5. If one eye has no or only weak optokinetic input, it will be driven by the other eye. The response mediated by the contralateral optokinetic stimulus diminishes if the amount of light impinging upon the driven eye is increased. 6. There is a logarithmic relationship between the response of the driving eye and that of the driven eye. 7. The possible biological significance of these relationships is seen in the enhanced coupling at low light intensities. 8. The variable strength of coupling and possible roles of movable eyes are discussed.
16
Matsuo, Megumi, Yasuhiro Kamei, and Shoji Fukamachi. "Behavioural red-light sensitivity in fish according to the optomotor response." Royal Society Open Science 8, no. 8 (August 2021): 210415. http://dx.doi.org/10.1098/rsos.210415.
Full textAbstract:
Various procedures have been adopted to investigate spectral sensitivity of animals, e.g. absorption spectra of visual pigments, electroretinography, optokinetic response, optomotor response (OMR) and phototaxis. The use of these techniques has led to various conclusions about animal vision. However, visual sensitivity should be evaluated consistently for a reliable comparison. In this study, we retrieved behavioural data of several fish species using a single OMR procedure and compared their sensitivities to near-infrared light. Besides cavefish that lack eyes, some species were not appropriate for the OMR test because they either stayed still or changed swimming direction frequently. Eight of 13 fish species tested were OMR positive. Detailed analyses using medaka, goldfish, zebrafish, guppy, stickleback and cichlid revealed that all the fish were sensitive to light at a wavelength greater than or equal to 750 nm, where the threshold wavelengths varied from 750 to 880 nm. Fish opsin repertoire affected the perception of red light. By contrast, the copy number of long-wavelength-sensitive ( LWS ) genes did not necessarily improve red-light sensitivity. While the duplication of LWS and other cone opsin genes that has occurred extensively during fish evolution might not aid increasing spectral sensitivity, it may provide some other advantageous ophthalmic function, such as enhanced spectral discrimination.
17
Kadlec, T., M. Pikner, and G. Piknerova. "Sex-biased response in activity to light sources with different spectral composition in geometrid moths with flightless females (Lepidoptera: Geometridae)." Bulletin of Entomological Research 106, no. 5 (April 28, 2016): 581–90. http://dx.doi.org/10.1017/s0007485316000298.
Full textAbstract:
AbstractGeometrid moths occurring in late autumn and early spring in temperate forest habitats are often harmful defoliators of deciduous stands. Their populations can cause locally cyclic outbreaks and thus preventive monitoring actions have been developed, mainly based on pheromone attraction of males. Females are mostly flightless with reduced or lost wings and reduced senses associated with flying. Males are standard flyers with well-developed eyes and must be able to deal with rapidly changing light conditions during their activity. Although such differences indicate sex-biased differences in reactions to light, this has been insufficiently tested. In conditions of an experimental arena and using light-emitting diodes, we tested the different reactions of the sexes for nine species to precisely defined short segments of the electromagnetic spectrum in the range 360–660 nm. Across all species, males preferred shorter wavelengths up to 500 nm, while females were nonselective and generally less active. The sexes differed by eye size and body mass, with males having significantly larger eyes and lower body mass. Between brachypterous and apterous females, the former had larger eye size, while body mass differences were statistically insignificant. There were differences between the sexes in move-to-light reactions and changes in eye size and body mass in line with wing reduction. While males preferred a relatively distinct range of shorter wavelengths, a method of attraction to lights with distinct narrow spectra could be used markedly to enhance the established methods of forest pest monitoring, either alone or in combination with chemical male attraction.
18
Castrogiovanni, Paolo, Fulvio Pieraccini, Sonia Iapichino, Claudia Pacchierotti, Letizia Bossini, Elisabetta Truglia, Claudio Malpassi, and Bruno Natale. "Electroretinogram B-Wave Amplitude in Panic Disorder." CNS Spectrums 6, no. 3 (March 2001): 210–13. http://dx.doi.org/10.1017/s1092852900008580.
Full textAbstract:
AbstractAbnormal light-related behaviors have been described for patients with panic disorder (PD). The present study was undertaken to investigate the retinal light response in PD using electroretinography (ERG). The authors conducted bwave ERG measurements with a bright light (after dark adaptation) in 28 patients with PD and 28 control subjects. There were no significant differences in the mean b-wave amplitude between the two groups, but the retinal response to light in PD patients was generally lower than in healthy subjects. A large interindividual variability was found; also noted was a significant difference in the mean b-wave amplitude between the right and left eyes in the control group. The data indicate subtle variation of retinal photosensitivity in a subgroup of patients with PD. Because dopaminergic retinal activity affects b-ERG amplitude, the authors hypothesize that the dopaminergic system is involved in the response to light in PD patients.
19
McCann, John J. "Increases in scattered light causes increased darkness." Electronic Imaging 2020, no. 15 (January 26, 2020): 279–1. http://dx.doi.org/10.2352/issn.2470-1173.2020.15.color-259.
Full textAbstract:
What we see is not a simple consequence of the light sent to our eyes. Vision has two powerful spatial transformations of scene luminances: one optical; the other neural. The first spatial redistribution of light is intraocular scatter. Scattered light reduces the dynamic range of the retinal image compared to light from the scene. The second spatial transformation comes from neural processing that causes appearances to vary with the scene’s content. A beach scene, (mostly max-luminance scene elements, and maximal scattered light) has the highest slope neural response function. The post-quanta-catch neural mechanisms overcompensate for the intraocular scatter. Low-reflectance objects look darker in scenes with maximal scatter
20
Edwards, Samuel C., Anne C. Wishart, Eric M. Wiebe, and Barbara-Anne Battelle. "Light-regulated proteins in Limulus ventral photoreceptor cells." Visual Neuroscience 3, no. 2 (August 1989): 95–105. http://dx.doi.org/10.1017/s0952523800004417.
Full textAbstract:
AbstractThe protein intermediates of the photoresponse and the modulation of this response in invertebrate photoreceptors are largely unknown. As a first step toward identifying these proteins, we have examined light-stimulated changes in protein phosphorylation in preparations of Limulus photoreceptors. Here we show that light modulates the level of phosphorylation of three proteins associated with Limulus ventral photoreceptors: the upper band of a 46-kD protein doublet (46A) and a 122-kD protein, which become more heavily phosphorylated in response to light, and the lower component of the 46-kD doublet (46B), which is phosphorylated in dark-adapted cells, but not in cells maintained in the light. In dark-adapted preparations, 46A is phosphorylated within 30 s after a flash of light and dephosphorylates over a period of many minutes. It is also a major substrate for calcium/calmodulin-dependent protein kinase (Wiebe et al., 1989); therefore, we speculate that 46A is involved in some aspect of dark adaptation. Interestingly, the level of phosphorylation of 46A is the same when measured from preparations maintained in complete darkness or ambient light for at least 1.5 h. The 122-kD phosphoprotein is the same protein which becomes phosphorylated in response to efferent innervation to Limulus eyes (Edwards et al., 1988) and the efferent neurotransmitter, octopamine (Edwards and Battelle, 1987). It may be involved in the increase in retinal sensitivity and the enhanced response of photoreceptors to light that is initiated by efferent innervation. Its role in light-stimulated processes is not clear. The level of phosphorylation of 46B may be most relevant to the long-term state of adaptation of the photoreceptor cell to light and dark.
21
BUI, BANG V., and BRAD FORTUNE. "Origin of electroretinogram amplitude growth during light adaptation in pigmented rats." Visual Neuroscience 23, no. 2 (March 2006): 155–67. http://dx.doi.org/10.1017/s0952523806232024.
Full textAbstract:
We assessed the growth of the rat photopic electroretinogram (ERG) during light adaptation and the mechanisms underlying this process. Full field ERG responses were recorded from anesthetized adult Brown–Norway rats at each minute for 20 min of light adaptation (backgrounds: 1.8, 2.1, 2.4 log scotopic cd m−2). The rat photopic b-wave amplitude increased with duration of light adaptation and its width at 33% maximal amplitude narrowed (by ∼ 40 ms). These effects peaked 12–15 min after background onset. The narrowing of the b-wave reflected steepening of the b-wave recovery phase, with little change in the rising phase. OP amplitudes grew in proportion to the b-wave. Inhibition of inner retinal responses using TTX resulted in a greater relative growth of b-wave and OP amplitude compared with fellow control eyes, and delayed the change in recovery phase by ∼ 5 min. Inhibition of all ionotropic glutamate receptors with CNQX/D-AP7 delayed both rising and recovery phases equally (∼ 12 ms) without altering b-wave width or the time course of adaptation changes. These outcomes suggest that inner retinal light responses are not directly responsible for b-wave amplitude growth, but may contribute to the change in its recovery phase during adaptation. A TTX-sensitive mechanism may help to hasten this process. The cone a-wave was isolated using PDA/L-AP4 or CNQX/L-AP4. A-wave amplitude (35 ms after stimulus onset) also increased with time during light adaptation and reached a maximum (130 ± 29% above baseline) 12–15 min after background onset. B-wave amplitude growth in fellow control eyes closely followed the course and relative magnitude of cone a-wave amplitude growth. Hence, the increase of the cone response during light adaptation is sufficient to explain b-wave amplitude growth.
22
Burton, Brian G., Ben W. Tatler, and Simon B. Laughlin. "Variations in Photoreceptor Response Dynamics Across the Fly Retina." Journal of Neurophysiology 86, no. 2 (August 1, 2001): 950–60. http://dx.doi.org/10.1152/jn.2001.86.2.950.
Full textAbstract:
Gradients in the spatial properties of retinal cells and their relation to image statistics are well documented. However, less is known of gradients in temporal properties, especially at the level of the photoreceptor for which no account exists. Using light flashes and white-noise-modulated light and current stimuli, we examined the spatial and temporal properties of a single class of photoreceptor (R1–6) within the compound eyes of male blowfly, Calliphora vicina. We find that there is a trend toward higher performance at the front of the eye, both in terms of spatiotemporal resolution and signal-to-noise ratio. The receptive fields of frontal photoreceptors are narrower than those of photoreceptors at the side and back of the eye and response speeds are 20% faster. The signal-to-noise ratio at high frequencies is also greatest at the front of the eye, allowing a 30–40% higher information rate. The power spectra of signals and noise indicate that this elevation of performance results both from shorter responses to individual photons and from a more reliable registration of photon arrival times. These distinctions are characteristic of adaptational changes that normally occur on increasing illumination. However, all photoreceptors were absorbing light at approximately the same mean photon rate during our recordings. We therefore suggest that frontal photoreceptors attain a higher state of light adaptation for a given photon rate. This difference may be achieved by a higher density of (Ca2+ permeable) light-gated channels. Consistent with this hypothesis, membrane-impedance measurements show that frontal photoreceptors have a higher specific conductance than other photoreceptors. This higher conductance provides a better temporal performance but is metabolically expensive. Across the eye, temporal resolution is not proportional to spatial (optical) resolution. Neither is it matched obviously to optic flow. Instead we examine the consequences of an improved temporal resolution in the frontal region for the tracking of small moving targets, a behavior exhibited by male flies. We conclude that the temporal properties of a given class of retinal neuron can vary within a single retina and that this variation may be functionally related to the behavioral requirements of the animal.
23
Schmidt, M. "Neurons in the cat pretectum that project to the dorsal lateral geniculate nucleus are activated during saccades." Journal of Neurophysiology 76, no. 5 (November 1, 1996): 2907–18. http://dx.doi.org/10.1152/jn.1996.76.5.2907.
Full textAbstract:
1. Neurons in the pretectal nuclear complex that project to the ipsilateral dorsal lateral geniculate nucleus (LGNd) were identified by antidromic activation after electrical LGNd stimulation in awake cats, and their response properties were characterized to retinal image shifts elicited either by external visual stimulus movements or during spontaneous saccadic eye movements on a stationary visual stimulus, and to saccades in darkness. Eye position was monitored with the use of a scleral search coil and care was taken to assure stability of the eyes during presentation of moving visual stimuli. 2. Of a total sample of 134 cells recorded, 27 neurons were antidromically activated by electrical LGNd stimulation. In addition, responses from neurons that were not activated from the LGNd were also analyzed, including 19 “retinal slip” cells, which selectively respond to slow horizontal stimulus movements, and 21 “jerk” cells, which are specifically activated by rapid stimulus shifts. All recorded neurons were located in the nucleus of the optic tract and in the posterior pretectal nucleus. 3. In the light, neurons identified as projecting to the LGNd responded maximally to saccadic eye movements and to externally generated sudden shifts of large visual stimuli. Slow stimulus drifts did not activate these neurons. Response latencies were shorter and peak activities were increased during saccades compared with pure visual stimulation. No systematic correlation between response latency, response duration, or the number of spikes in the response and saccade direction, saccade amplitude, or saccade duration was found. Saccades and rapid stimulus shifts in the light also activated jerk cells but not retinal slip cells. 4. All 27 antidromically activated neurons also responded to spontaneous saccadic eye movements in complete darkness. Responses to saccades in the dark, however, had longer response latencies and lower peak activities than responses to saccades in light. As in the light, response parameters in darkness seemed not to code specific saccade parameters. Cells that were not activated from LGNd were found to be unresponsive to saccades in the dark. 5. According to their specific activation by saccades in darkness, LGNd-projecting pretectal neurons are termed “saccade neurons” to distinguish them from other pretectal cell populations, in particular from jerk neurons, which show similar response properties in light. 6. The saccade-related activation of pretectal saccade neurons may be used to modulate visual responses of LGNd relay cells following saccadic eye movements. Because the pretectogeniculate projection in cat most likely is GABAergic and terminates on inhibitory LGNd interneurons, its activation may lead to a saccade-locked disinhibition of relay cells. This input could counter the strong inhibition induced in the LGNd after shifts of gaze direction and lead to a resetting of LGNd cell activity.
24
Podolak, Olivia E., Kristy B. Arbogast, Joshi B. Nabin, Kenneth Ciuffreda, Matthew Grady, and Christina L. Master. "The use Of Pupillary Light Reflex in Concussed Athletes." Orthopaedic Journal of Sports Medicine 8, no. 4_suppl3 (April 1, 2020): 2325967120S0027. http://dx.doi.org/10.1177/2325967120s00277.
Full textAbstract:
Background: Despite advancements, concussion diagnosis remains reliant on subjective symptom report and clinical assessments. Visual deficits and autonomic dysfunction have been described following concussion. Testing of the pupillary light reflex (PLR) is a simple, portable, non-invasive, and objective means of quantifying pupillary function. Purpose: The aim of this study was to objectively evaluate pupillary responses to a light stimulus in concussed adolescent athletes and to determine whether clinical assessments correlated with PLR responses after a diagnosed concussion when compared to pre-injury responses. Methods: In this prospective cohort study, PLR and clinical measures [PCSI and/or SCAT symptom scales, near point of convergence (NPC) and accommodation amplitude (AA) of both eyes] were assessed in 93 (45 female), non-concussed adolescent athletes (ages 14-18) during their pre-season. PLR was obtained in response to a brief white light stimulus using a hand-held pupillometer. During each assessment, three monocular trials were performed in each eye alternatively, with subsequent averaged responses for each eye. Seven athletes (ages 14-17) sustained a concussion and had post-injury assessments of PLR and clinical measures completed longitudinally through recovery. Results: All seven concussed athletes completed PLR and clinical assessments at least once post-injury (mean initial day of evaluation = 6 days post injury). Six out of the seven concussed athletes demonstrated an increase in steady state diameter of 24% (median 18%), minimum pupil diameter of 17% (median 11%) and a maximum constriction velocity of 28% (median 33%) following concussion which decreased over the course of recovery, returning to pre-injury or below pre-injury measurements. Six of seven of the concussed athletes completed NPC and AA assessments at both pre-season and post-injury timepoints. In contrast to the PLR findings, both NPC and AA measures were normal at post-injury assessments. Reported symptom scores improved throughout recovery, correlating with PLR response recovery, with both returning to pre-injury measurements. Conclusion: Pupil responsivity was found to be significantly enhanced after concussion compared to pre-injury measurements, waning over time during recovery, following a similar trajectory as symptom burden. NPC and AA, which have autonomic contributions and are clinical measures, were normal pre- and post-injury and did not differentiate the concussed state from the uninjured state in our series. Our preliminary results demonstrate that dynamic PLR responses may detect acute autonomic deficits that are not evident via clinical assessments. Further investigation of its potential utility as sensitive and objective biomarker in concussion diagnosis, management and sports clearance is warranted.
25
Nordstrom, P., and E. J. Warrant. "Temperature-induced pupil movements in insect superposition eyes." Journal of Experimental Biology 203, no. 4 (February 15, 2000): 685–92. http://dx.doi.org/10.1242/jeb.203.4.685.
Full textAbstract:
In this paper, we describe the hitherto largely overlooked effect of temperature on the pupil of insect compound eyes. In the turnip moth Agrotis segetum and in two other nocturnal insects with superposition eyes, the lacewing Euroleon nostras and the codling moth Cydia pomonella, the pupil not only opens and closes with changes in the ambient light level, as expected, but also with changes in temperature in the absence of light. In complete darkness, the pupil of A. segetum responds over a wide range of temperatures, with the pupillary pigments migrating to a light-adapted position when the animal is exposed to either low or high temperatures. At temperatures between 21.0 and 22.7 C, the pigments migrate to the fully dark-adapted position, resulting in an open pupil and maximal eye glow. Pupil closure at high temperatures shows two distinct thresholds: the first at 23.8+/−0.7 C and a second some degrees higher at 25.7+/−1.2 C (means +/− s.d., N=10). Temperatures exceeding the first threshold (the activation temperature, T(a)) initiate a closure of the pupil that is completed when the temperature exceeds the second threshold (the closure temperature, T(c)), which causes rapid and complete migration of pigment to the light-adapted position. All temperatures above T(a) affect the pupil, but only temperatures exceeding T(c) result in complete closure. Temperatures between T(a) and T(c) cause a slow, partial and rather unpredictable closure. The lacewing and the codling moth both show very similar responses to those of A. segetum, suggesting that this response to temperature is widespread in superposition eyes. The possibility that the ambient temperature could be used to pre-adapt the eye to different light intensities is discussed.
26
Zhao, Dapeng, Yan Yin, Chao Liu, Chunsong Lu, and Xiaofeng Xu. "Can the Aerosol Absorption Ångström Exponent Represent Aerosol Color in the Atmosphere: A Numerical Study." Atmosphere 11, no. 2 (February 11, 2020): 187. http://dx.doi.org/10.3390/atmos11020187.
Full textAbstract:
The aerosol absorption Ångström exponent (AAE) is widely used to indicate aerosol absorption spectrum variations and is an important parameter for characterizing aerosol optical absorption properties. This study discusses the relationship between aerosol AAEs and their colors numerically. By combining light scattering simulations, a two-stream radiative transfer model, and an RGB (Red, Green, and Blue) color model, aerosol colors that can be sensed by human eyes are numerically generated with both the solar spectrum and human eye response taken into account. Our results indicate that the responses of human eyes to visible light might be more significant than the incident spectrum in the simulation of aerosol color in the atmosphere. Using the improved numerical simulation algorithm, we obtain the color change of absorption aerosols with different AAEs. When the AAE value is small, the color of the aerosol is generally black and gray. When the AAE value increases to approximately 2 and the difference between the light transmittances at wavelengths of 400 nm and 730 nm is greater than 0.2, the aerosol will appear brown or yellow.
27
Tomasso, Livia, Lucia Benatti, Alessandro Rabiolo, Adriano Carnevali, Ilaria Zucchiatti, Lea Querques, Francesco Bandello, and Giuseppe Querques. "Retinal vessels functionality in eyes with central serous chorioretinopathy." British Journal of Ophthalmology 102, no. 2 (June 9, 2017): 210–14. http://dx.doi.org/10.1136/bjophthalmol-2017-310398.
Full textAbstract:
PurposeTo analyse static characteristics and dynamic functionality of retinal vessels in eyes with central serous chorioretinopathy (CSCR) by means of Dynamic Vessel Analyzer (DVA).MethodsPatients presenting with treatment-naïve CSCR and normal subjects (controls) matched for age and sex between May 2015 and November 2015 were enrolled in the study. Participants underwent a complete ophthalmological examination, including dynamic and static retinal vessels analysis by DVA.ResultsA total of 28 eyes of 28 subjects (14 eyes for each group) were included in the analysis. Dynamic analysis during stimulation by flickering light showed mean venous dilation of 3.3%±2.0% in patients with CSCR and 5.5%±2.6% in controls (p=0.0258); mean arterial dilation did not differ between patients and controls (3.2%±2.5% and 4.2%±1.5%, p=0.2). No differences were reported at static retinal analysis between patients with CSCR and control subjects. Subfoveal choroidal thickness as evaluated by optical coherence tomography was 438.6±86.1 µm in CSCR eyes, significantly increased compared with control subjects (301.5±72.5 µm, p=0.0001).ConclusionsDynamic analysis revealed a reduced retinal venous dilation in response to flicker light stimulation in CSCR eyes. The decreased retinal vein response to flicker light stimulation, possibly due to increased sympathetic tone and potentially leading to venous stasis, together with the increased choroidal thickness may help understand CSCR and give insights in its pathogenesis.
28
J, Michael Selbach, Maurice Schallenberg, Sebastian Kramer, Gerasimos Anastassiou, Klaus-Peter Steuhl, Walthard Vilser, and Stephan Kremmer. "Trabeculectomy Improves Vessel Response Measured by Dynamic Vessel Analysis (DVA) in Glaucoma Patients." Open Ophthalmology Journal 8, no. 1 (October 22, 2014): 75–81. http://dx.doi.org/10.2174/1874364101408010075.
Full textAbstract:
Purpose : To determine the effects of surgical IOP reduction (trabeculectomy) on retinal blood flow parameters in glaucoma patients using Dynamic Vessel Analysis (DVA). Methods : 26 eyes of 26 patients with progressive primary open-angle glaucoma (POAG) despite maximal topical therapy were examined before and after trabeculectomy. The responses of the retinal vessels to flickering light provocation were measured with DVA the day before surgery and 4 to 6 weeks after trabeculectomy. Between 3 and 4 weeks before surgery all local therapies were stopped and a systemic therapy with acetazolamide and conservative free topic steroidal eye drops was started. Results : In 19 patients (73%), an inadequate response to the flicker stimulation was measured preoperatively. In these patients, the maximum dilation of arteries and veins was reduced significantly as compared to healthy eyes. In this group, the maximum dilation of the arteries following the flicker provocation improved from 1.4% before to 3.8% following trabeculectomy (p<0.01). In retinal veins, this parameter increased from 3.1% to 4.6% (p<0.05). In the 7 patients whose arterial and venous reactions to flickering light provocation preoperatively did not differ from healthy eyes, there was no significant change after surgery. The initial baseline values of arteries and veins (MU) did not deviate significantly in both groups. Conclusion : POAG patients with progressive disease and impaired vascular regulation profit from IOP lowering trabeculectomy concerning vascular reactivity and dilative reserve, indicating a possible improvement of retinal perfusion following effective IOP control. Future studies with long-term follow-up must determine the clinical importance of these findings for the treatment of glaucoma patients.
29
Herzon, Garrett D., and David L. Zealear. "Intraoperative Monitoring of the Visual Evoked Potential during Endoscopic Sinus Surgery." Otolaryngology–Head and Neck Surgery 111, no. 5 (November 1994): 575–79. http://dx.doi.org/10.1177/019459989411100507.
Full textAbstract:
Iatrogenic blindness resulting from conventional and endoscopic sinus surgery continues to be a major concern to the head and neck surgeon. A new electrophysiologic monitoring technique has been developed that can help avoid damage to the optic nerve and visual system. The approach involves monitoring the visual evoked potential with presentation of flash stimuli to the eyes. Thirty patients with chronic sinusitis underwent endoscopic sinus surgery with visual evoked potential monitoring. The procedures were carried out with patients under intravenous general anesthesia. Needle cortical electrodes were placed in the scalp. A modified light-emitting diode array/goggle was positioned in front of the patient's closed eyes. A triggered flash of 2 Hz was delivered through the goggle to stimulate the patient's retina. Cortical responses were amplified and averaged for 100 trials. Amplitude and peak-latency changes were monitored to alert the surgeon to any change in the visual response during the surgical dissection. Although no changes in response were noted during dissection, cold-water irrigation and reflected telescopic light could produce variations in the recorded responses, as will be discussed. Visual evoked potential monitoring may prevent a surgeon from continuing a bilateral procedure when there is indication of iatrogenic visual loss from dissection on the first side. Visual evoked potential also reassures the operator that no damage has occurred to the visual pathway at the conclusion of a case. Methods, case selection, operative technique, and documentation of monitoring will be discussed.
30
King-Smith, Christina, and Thomas W. Cronin. "Pigment granule migration in crustacean photoreceptors requires calcium." Visual Neuroscience 13, no. 1 (January 1996): 43–49. http://dx.doi.org/10.1017/s0952523800007112.
Full textAbstract:
AbstractWe have investigated the role of calcium in the regulation of pigment granule migration in photoreceptors of the semi-terrestrial crab, Sesarma cinereum. Isolated crab eyes (eyecup plus eyestalk) were maintained in crustacean Ringer either prepared normally or calcium-free plus 50 mM EGTA. Pigment granule movement was indirectly observed by monitoring reflectance from the eye during light stimuli using intracellular optical physiological techniques. Electroretinograms (ERGs) were also measured during light stimuli. EGTA treatment caused gradual loss of centripetal migration of pigment granules (normally leading to pupillary closure), and photoreceptors eventually became locked in the open-pupil, dark-adapted state despite repeated stimuli. In contrast, ERG responses continued throughout EGTA treatment, although the size and shape ofthe response was altered. Normal ERG responses and pigment granule movements returned after replacing EGTA-Ringer with normal-calcium medium. These results suggest that centripetal migration of pigment granules in crustacean photoreceptors requires calcium.
31
Chen, Xun, Tian Han, Feng Zhao, Huamao Miao, Xiaoying Wang, and Xingtao Zhou. "Evaluation of Disk Halo Size after Implantation of a Collamer Lens with a Central Hole (ICL V4c)." Journal of Ophthalmology 2019 (August 14, 2019): 1–6. http://dx.doi.org/10.1155/2019/7174913.
Full textAbstract:
Purpose. To investigate disk halo size changes produced by a glare source after surgical insertion of an implantable collamer lens with a central hole (ICL V4c) for myopia correction. Methods. In this prospective study, disk halo size and pupillary light response with a vision monitor were measured preoperatively and at 1 week, 1 month, and 3 months postoperatively. Pupillary light response parameters included contraction amplitude, latency, duration, and velocity; dilation latency, duration, and velocity; and initial, maximum, minimum, and average pupil diameters. Results. Forty-two right eyes of 42 patients were enrolled. Postoperative uncorrected distance visual acuity was better than or equal to 20/20 in all eyes. Compared to preoperative values, disk halo size showed no significant difference at 1 week postoperatively (P>0.05) and then decreased significantly at 1 and 3 months postoperatively (both P<0.001). Contraction amplitude and velocity, as well as dilation velocity, decreased significantly at all postoperative time points (all P<0.001). Disk halo size at 3 months postoperatively was significantly correlated with initial (r = 0.446, P=0.003), maximum (r = 0.483, P=0.001), minimum (r = 0.425, P=0.005), and average pupil diameters (r = 0.474, P=0.002). Conclusions. After ICL V4c implantation, disk halo size was reduced in the short term. Patients with smaller pupil sizes during pupillary response to light experienced smaller halos after ICL V4c implantation.
32
Mizunami, M., H. Tateda, and K. Naka. "Dynamics of cockroach ocellar neurons." Journal of General Physiology 88, no. 2 (August 1, 1986): 275–92. http://dx.doi.org/10.1085/jgp.88.2.275.
Full textAbstract:
The incremental responses from the second-order neurons of the ocellus of the cockroach, Periplaneta americana, have been measured. The stimulus was a white-noise-modulated light with various mean illuminances. The kernels, obtained by cross-correlating the white-noise input against the resulting response, provided a measure of incremental sensitivity as well as of response dynamics. We found that the incremental sensitivity of the second-order neurons was an exact Weber-Fechner function; white-noise-evoked responses from second-order neurons were linear; the dynamics of second-order neurons remain unchanged over a mean illuminance range of 4 log units; the small nonlinearity in the response of the second-order neuron was a simple amplitude compression; and the correlation between the white-noise input and spike discharges of the second-order neurons produced a first-order kernel similar to that of the cell's slow potential. We conclude that signal processing in the cockroach ocellus is simple but different from that in other visual systems, including vertebrate retinas and insect compound eyes, in which the system's dynamics depend on the mean illuminance.
33
Vigo, Luca, Leonardo Taroni, Federico Bernabei, Marco Pellegrini, Stefano Sebastiani, Andrea Mercanti, Nicola Di Stefano, Vincenzo Scorcia, Francesco Carones, and Giuseppe Giannaccare. "Ocular Surface Workup in Patients with Meibomian Gland Dysfunction Treated with Intense Regulated Pulsed Light." Diagnostics 9, no. 4 (October 13, 2019): 147. http://dx.doi.org/10.3390/diagnostics9040147.
Full textAbstract:
The purpose of the present study was to evaluate changes of signs and symptoms in patients with meibomian gland dysfunction (MGD) treated with intense regulated pulsed light (IRPL), and to further investigate which parameter could predict positive outcomes of the procedure. Twenty-eight patients who bilaterally received three IRPL sessions at day 1, 15, and 45 satisfied the criteria and were included in the study. Non-invasive break-up time (NIBUT), lipid layer thickness (LLT), meibography, tear osmolarity, and ocular discomfort symptoms were measured before and 30 days after the last IRPL session. Qualified or complete success was defined in the presence of an improvement of symptoms associated with an increase of NIBUT (< or ≥ 20%). After IRPL treatment, median NIBUT and LLT increased from 7.5 to 10.2 s and 2.0 to 3.0, respectively (p <0.001); tear osmolarity decreased from 304.0 to 301.0 mOsm/L (p = 0.002). Subjective symptoms improved after IRPL in 26 patients. Qualified success was reached in 34 eyes, while complete success in 16 eyes. Patients with lower baseline break-up time (BUT) values showed better response to treatment (p = 0.04). In conclusion, IRPL improved signs and symptoms in MGD patients, while lower baseline NIBUT values were predictive of better response to IRPL.
34
Rom-Glas, A., C. Sandler, K. Kirschfeld, and B. Minke. "The nss mutation or lanthanum inhibits light-induced Ca2+ influx into fly photoreceptors." Journal of General Physiology 100, no. 5 (November 1, 1992): 767–81. http://dx.doi.org/10.1085/jgp.100.5.767.
Full textAbstract:
Ion-selective calcium microelectrodes were inserted into the compound eyes of the wild-type sheep blowfly Lucilia or into the retina of the no steady state (nss) mutant of Lucilia. These electrodes monitored light-induced changes in the extracellular concentration of calcium (delta[Ca2+]o) together with the extracellularly recorded receptor potential. Prolonged dim lights induced a steady reduction in [Ca2+]o during light in the retina of normal Lucilia, while relatively little change in [Ca2+]o was observed in the retina of the nss mutant. Prolonged intense light induced a multiphasic change in [Ca2+]o: the [Ca2+]o signal became transient, reaching a minimum within 6 s after light onset, and then rose to a nearly steady-state phase below the dark concentration. When lights were turned off, a rapid increase in [Ca2+]o was observed, reaching a peak above the dark level and then declining again to the dark level within 1 min. In analogy to similar studies conduced in the honeybee drone, we suggest that the reduction in [Ca2+]o reflects light-induced Ca2+ influx into the photoreceptors, while the subsequent increase in [Ca2+]o reflects the activation of the Na-Ca exchange which extrudes Ca2+ from the cells. In the nss mutant in response to intense prolonged light, the receptor potential declines to baseline during light while the Ca2+ signal is almost abolished, revealing only a short transient reduction in [Ca2+]o. Application of lanthanum (La3+), but not nickel (Ni2+), into the retinal extracellular space of normal Lucilia mimicked the effect of the nss mutation on the receptor potential, while complete elimination of the Ca2+ signal in a reversible manner was observed. The results suggest that La3+ and the nss mutation inhibit light-induced Ca2+ influex into the photoreceptor in a manner similar to the action of the trp mutation in Drosophila, which has been shown to block specifically a light-activated Ca2+ channel necessary to maintain light excitation.
35
Freeman, Daniel K., Gilberto Graña, and Christopher L. Passaglia. "Retinal Ganglion Cell Adaptation to Small Luminance Fluctuations." Journal of Neurophysiology 104, no. 2 (August 2010): 704–12. http://dx.doi.org/10.1152/jn.00767.2009.
Full textAbstract:
To accommodate the wide input range over which the visual system operates within the narrow output range of spiking neurons, the retina adjusts its sensitivity to the mean light level so that retinal ganglion cells can faithfully signal contrast, or relative deviations from the mean luminance. Given the large operating range of the visual system, the majority of work on luminance adaptation has involved logarithmic changes in light level. We report that luminance gain controls are recruited for remarkably small fluctuations in luminance as well. Using spike recordings from the rat optic tract, we show that ganglion cell responses to a brief flash of light are modulated in amplitude by local background fluctuations as little as 15% contrast. The time scale of the gain control is rapid (<125 ms), at least for on cells. The retinal locus of adaptation precedes the ganglion cell spike generator because response gain changes of on cells were uncorrelated with firing rate. The mechanism seems to reside within the inner retinal network and not in the photoreceptors, because the adaptation profiles of on and off cells differed markedly. The response gain changes follow Weber's law, suggesting that network mechanisms of luminance adaptation described in previous work modulates retinal ganglion cell sensitivity, not just when we move between different lighting environments, but also as our eyes scan a visual scene. Finally, we show that response amplitude is uniformly reduced for flashes on a modulated background that has spatial contrast, indicating that another gain control that integrates luminance signals nonlinearly over space operates within the receptive field center of rat ganglion cells.
36
Underwood, H. "Extraretinal photoreception in the lizard Sceloporus occidentalis: phase response curve." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 248, no. 4 (April 1, 1985): R407—R414. http://dx.doi.org/10.1152/ajpregu.1985.248.4.r407.
Full textAbstract:
All submammalian vertebrates have extraretinal photoreceptors (ERR) that can mediate entrainment of circadian rhythms to 24-h light-dark (LD) cycles. Phase response curves (PRC) for 6-h fluorescent light pulses were generated for lizards (Sceloporus occidentalis) previously subjected to sectioning of both optic nerves (ONX). The PRC for ONX lizards (only ERRs present) shows a threefold increase in the amplitude of both the advance and delay portions of the PRC compared with a PRC previously generated for sighted S. occidentalis. Also, in contrast to sighted lizards the area of the advance part of the PRC of ONX lizards is greater than the delay portion. Consistent with the shape of the respective PRCs in ONX vs. sighted lizards are the following facts. 1) The range of entrainment to LD cycles is greater in ONX lizards; some sighted lizards free-ran when exposed to LD 6:21.5 or LD 6:23.5 but entrained after ONX lizards reentrained to an 8-h shift in the phase of a LD 6:18 cycle significantly faster than sighted lizards. 3) Forty-two percent of ONX lizards showed a shorter free-running period (tau) in LL than DD, whereas 90% of sighted lizards showed a longer free-running period in LL than in DD. In those lizards in which tau LL greater than tau DD, the the average tau change in ONX lizards in was significantly less than that observed in sighted lizards. These results are consistent with the hypothesis that the eyes have an "inhibitory" role in the circadian system of S. occidentalis.
37
Radel, J. D., D. J. Kustra, and R. D. Lund. "The pupillary light response: Functional and anatomical interaction among inputs to the pretectum from transplanted retinae and host eyes." Neuroscience 68, no. 3 (October 1995): 893–907. http://dx.doi.org/10.1016/0306-4522(95)00191-k.
Full text
38
Gonzalez-Lopez, Felix, Blas Mompean, Rafael Bilbao-Calabuig, Jorge Vila-Arteaga, Jaime Beltran, and Julio Baviera. "Response to “Vault Changes Caused by Light-Induced Pupil Constriction and Accommodation in Eyes With an Implantable Collamer Lens”." Cornea 38, no. 9 (September 2019): e36-e37. http://dx.doi.org/10.1097/ico.0000000000002020.
Full text
39
Pereira-da-Mota, Ana F., Jéssica Costa, Ana Amorim-de-Sousa, José M. González-Méijome, and António Queirós. "The Impact of Overnight Orthokeratology on Accommodative Response in Myopic Subjects." Journal of Clinical Medicine 9, no. 11 (November 17, 2020): 3687. http://dx.doi.org/10.3390/jcm9113687.
Full textAbstract:
This study aimed to evaluate the effects of two months of orthokeratology (OK) treatment in the accommodative response of young adult myopes. Twenty eyes (21.8 ± 1.8 years) were fitted with the Paragon CRT® 100 LENS to treat myopia between −1.00 and −2.00 D. Low- and high-contrast visual acuity (LCDVA and HCDVA), central objective refraction, light disturbance (LD), and objective accommodative response (using the Grand Seiko WAM-5500 open-field autorefractometer coupled with a Badal system) were measured at baseline (BL) before lens wear and after 1, 15, 30, and 60 nights of OK. Refractive error correction was achieved during the first fifty days of OK lens wear, with minimal changes afterwards. LD analysis showed a transient increase followed by a reduction to baseline levels over the first 30 nights of treatment. The accommodative response was lower than expected for all target vergences in all visits (BL: 0.61 D at 1.00 D to 0.96 D at 5.00 D; 60 N: 0.36 D at 1.00 D to 0.79 D at 5.00 D). On average, the accommodative lag decreases over time with OK lens wear. However, these differences were not statistically significant (p > 0.050, repeated-measures ANOVA and Friedman test). This shows that overnight OK treatment does not affect objectively measured the accommodative response of young, low myopic eyes after two months of treatment stabilization.
40
Hoffmann, Susanne, Alexandra Bley, Mariana Matthes, Uwe Firzlaff, and Harald Luksch. "The Neural Basis of Dim-Light Vision in Echolocating Bats." Brain, Behavior and Evolution 94, Suppl. 1-4 (2019): 61–70. http://dx.doi.org/10.1159/000504124.
Full textAbstract:
Echolocating bats evolved a sophisticated biosonar imaging system that allows for a life in dim-light habitats. However, especially for far-range operations such as homing, bats can support biosonar by vision. Large eyes and a retina that mainly consists of rods are assumed to be the optical adjustments that enable bats to use visual information at low light levels. In addition to optical mechanisms, many nocturnal animals evolved neural adaptations such as elongated integration times or enlarged spatial sampling areas to further increase the sensitivity of their visual system by temporal or spatial summation of visual information. The neural mechanisms that underlie the visual capabilities of echolocating bats have, however, so far not been investigated. To shed light on spatial and temporal response characteristics of visual neurons in an echolocating bat, Phyllostomus discolor, we recorded extracellular multiunit activity in the retino-recipient superficial layers of the superior colliculus (SC). We discovered that response latencies of these neurons were generally in the mammalian range, whereas neural spatial sampling areas were unusually large compared to those measured in the SC of other mammals. From this we suggest that echolocating bats likely use spatial but not temporal summation of visual input to improve visual performance under dim-light conditions. Furthermore, we hypothesize that bats compensate for the loss of visual spatial precision, which is a byproduct of spatial summation, by integration of spatial information provided by both the visual and the biosonar systems. Given that knowledge about neural adaptations to dim-light vision is mainly based on studies done in non-mammalian species, our novel data provide a valuable contribution to the field and demonstrate the suitability of echolocating bats as a nocturnal animal model to study the neurophysiological aspects of dim-light vision.
41
Witkovsky, Paul, and Xiao-Ping Shi. "Slow light and dark adaptation of horizontal cells in the Xenopus retina: A role for endogenous dopamine." Visual Neuroscience 5, no. 04 (October 1990): 405–13. http://dx.doi.org/10.1017/s0952523800000493.
Full textAbstract:
AbstractA role for endogenous dopamine in the control of rod and contributions to a second-order retinal neuron, the horizontal cell (HC) was studied in theXenopusretina. Relative rod and cone contributions were estimated from HC responses to scotopically balanced 491- and 650-nm flashes. In eyecups prepared in light then placed in darkness, cone input to the HC slowed and diminished on a time scale of hours. The decline in cone input was balanced by a slow growth of rod input to the HC. Administration of D-amphetamine, a dopamine releasing agent, restored the light-adapted waveform.The kinetics of slow light adaptation were examined by recording HC responses from eyecups that had been dark-adapted previously for 11–14 h. When test flashes fell on a dark field, cone input to the HC grew for 2–4 h, reached a plateau, and later declined. If, however, flashes were superimposed on a weak background field, cone input to the HC continued to increase monotonically at about 10%/h. This increase was abolished by superfusion with a nonspecific dopamine receptor blocker, cis-flupenthixol (50 μM), resulting in the complete suppression of cone-to-horizontal cell synaptic transfer and the enhancement of rod-to-horizontal cell communication. Subcutaneous injection of reserpine, a drug that depletes dopamine stores (2 mg/kg on 1–4 successive days), or intraocular injection of the dopamine neurotoxin, 6-hydroxydopamine (10–30 μg) slowed and reduced the amplitude of cone input to the HC, even in completely light-adapted eyes. Subsequent treatment with D-amphetamine (5–50 μM) or dopamine (10 μM) partially restored the normal response.Our experimental findings are consistent with the following hypothesis. Weak light is sufficient to stimulate dopamine release; dopamine augments cone-to-horizontal cell synaptic transfer and reduces rod-to-horizontal cell communication. The rapid kinetics of the fully light-adapted response depend on the presence of dopamine. Thus, dopamine appears to be an intraretinal signal for slow light adaptation.
42
Wenzl, Elfriede, Matthias G. Wirtitsch, and Navid Ardjomand. "Yellow Intraocular Lenses – To Block or Not to Block." European Ophthalmic Review 03, no. 02 (2009): 77. http://dx.doi.org/10.17925/eor.2009.03.02.77.
Full textAbstract:
Yellow filters for the eye have been of interest to ophthalmologists and optometrists for the last 30 years. Certain fish species can change the colour of the cornea in response to the level of illumination and regulate the amount of short-wavelength light reaching the retina. A positive influence of yellow eye filters on reduction of chromatic aberration has been found in a fish eye model. Blue-light-filter (yellow) intraocular lenses (IOLs) were introduced for cataract surgery almost 20 years ago. The main advantage of yellow IOLs is thought to be the reduction of chromatic aberration under photopic conditions and protection of the retina from phototoxic short-wavelength light, especially in eyes at risk of age-related macular degeneration (AMD). This article highlights the importance of yellow IOLs for cataract surgery in terms of quality of vision and AMD protection.
43
Finn, Roderick Nigel, and Ivar Rønnestad. "The effect of acute changes in temperature and light on the aerobic metabolism of embryos and yolk-sac larvae of turbot (Scophthalmus maximus)." Canadian Journal of Fisheries and Aquatic Sciences 60, no. 11 (November 1, 2003): 1324–31. http://dx.doi.org/10.1139/f03-113.
Full textAbstract:
The effect of acute changes of temperature and light on the rates of oxygen consumption and ammonia excretion of developing embryos and yolk-sac larvae of turbot (Scophthalmus maximus) reared at 15 °C were studied. Short-term temperature adjustments of ±2 °C gave a mean Q10 of 2.6 for the rate of oxygen consumption. Neither the presence nor the absence of light significantly influenced this response to acute temperature changes, despite light causing a significantly higher rate of oxygen consumption in the yolk-sac larvae between 9 and 12 days after fertilisation. This elevated metabolic rate in the presence of light occurred after pigmentation of the eyes and was probably due to activity associated with food-searching behaviour of this visual feeder. Similarly, for most development, the presence or absence of light and acute temperature adjustments did not cause any significant shift in the relative fraction of amino acids catabolised at 15 °C. However, on day 10 after fertilisation when peak rates of oxygen consumption occurred in the yolk-sac larvae exposed to light, the significantly elevated apparent nitrogen quotients indicated that greater amounts of amino acids were utilised for catabolic substrate oxidation.
44
Popova, E. "Effects of dopamine receptor blockade on the intensity-response function of electroretinographic b- and d-waves in light-adapted eyes." Journal of Neural Transmission 121, no. 3 (October 23, 2013): 233–44. http://dx.doi.org/10.1007/s00702-013-1103-0.
Full text
45
Gaten, E., P. M. J. Shelton, C. J. Chapman, and A. M. Shanks. "Depth related variation in the structure and functioning of the compound eye of the Norway lobster Nephrops norvegicus." Journal of the Marine Biological Association of the United Kingdom 70, no. 2 (May 1990): 343–55. http://dx.doi.org/10.1017/s0025315400035451.
Full textAbstract:
The mobility and quantity of retinula cell proximal screening pigment, and the liability of the eyes to light-induced damage, were investigated in the Norway lobster, Nephrops norvegicus (L.), obtained from three separate populations from depths of 18, 75, and 135 m.During the morning after capture, the migration of the proximal pigment in response to the onset of illumination below the threshold for damage varied between the three populations. In the eyes of deep water N. norvegicus, the proximal screening pigment was located close to or below the basement membrane when dark-adapted and rose to a position midway up the rhabdoms when light-adapted. In the dark-adapted N. norvegicus from shallow water the proximal pigment was located more distally than in eyes of deep water animals. After the onset of illumination, the pigment migrated distally to completely cover the rhabdoms. The amount of retinula cell proximal screening pigment was found to decrease linearly with depth.When dark-adapted individuals from each depth were exposed to light a positive correlation was obtained between the photon fluence rate (PER) and the proportion of the retina damaged. For a given light exposure the amount of damage was highest in animals from deeper water. The PFR causing 25% damage was approximately 1 log unit higher in animals from 18 m compared to those from 135 m.The amount of damage varied with the delay between capture of the animals and exposure to light. When exposed 2 h after capture significant differences between depths were seen but the results were influenced by the incomplete dark adaptation of some specimens.
46
Murphy, Melanie J., and Sheila Gillard Crewther. "Ouabain inhibition of Na/K-ATPase across the retina prevents signed refractive compensation to lens-induced defocus, but not default ocular growth in young chicks." F1000Research 2 (March 28, 2013): 97. http://dx.doi.org/10.12688/f1000research.2-97.v1.
Full textAbstract:
Purpose: The relevance of retinal integrity and energy pathways to ocular growth and induction of refractive errors has seldom been investigated. Thus, we used ouabain to target the channels that are essential for the maintenance of membrane potentials in cells, sodium potassium ATPase (Na/K-ATPase), to examine refractive compensation and ocular growth in response to lens-induced defocus in the chick.Methods: A single intravitreal injection of 1 mM ouabain in dimethyl sulfoxide (DMSO) carrier or DMSO alone was followed by monocular defocus with positive or negative 10 D lens (or no lens) from post-hatching days 5-9 under 12/12 hr light/dark conditions. Biometry and dark-adapted flash and electroretinography (ERG) were conducted on day 9, followed by immunohistological analyses.Results: Ouabain inhibited differential ocular growth and refractive compensation to signed defocus compared to DMSO. By 4-days post-ouabain injection all components of the typical ERG responses to light had been eliminated, and widespread histological damage was apparent, though some ‘default state’ ocular growth was measurable. Immunohistochemistry demonstrated reduction in the specialized water channel Aquaporin 4 (AQP4) expression and increased evidence of caspase 3 expression (a cell death associated protein) in ouabain-treated eyes compared with DMSO alone.Conclusion: The current study demonstrates that blockade of photoreceptor and inner retinal responses to light onset and offset by ouabain inhibits differential refractive compensation to optical blur, but does not prevent ocular growth.
47
Samie, Faramarz H., Robert N. Jinks, William W. Weiner, and Steven C. Chamberlain. "The morphology and physiology of a “mini-ommatidium” in the median optic nerve of Limulus polyphemus." Visual Neuroscience 12, no. 1 (January 1995): 69–76. http://dx.doi.org/10.1017/s095252380000732x.
Full textAbstract:
AbstractExamination of the Limulus median optic nerve with low-magnification light microscopy allows clear visualization of an ultraviolet-sensitive mini-ommatidium enshrouded by pigment cells, glial cells, and guanophores. Serial 1-μm sections of median optic nerves containing mini-ommatidia revealed the presence of a single, heavily pigmented photoreceptor (retinular) cell and a single, unpigmented arhabdomeric cell. Computer-assisted serial reconstructions from 1-μm sections confirmed the presence of two cells, each bearing a nucleus, and two axons leaving the mini-ommatidium. The retinular cell is morphologically similar to retinular cells from the median and lateral eyes. Its rhabdomere appears to be a continuous sheet of microvilli with much infolding. The structure of the arhabdomeric cell is nearly identical to those found in the median ocellus. As in other photoreceptors in Limulus, the retinular cell of the mini-ommatidium is innervated by efferent fibers from the brain. Each mini-ommatidium generates a single train of nerve impulses in response to light, presumably from the arhabdomeric cell. Measurement of the spectral sensitivity of the mini-ommatidium based upon a constant-response criterion indicated that the retinular cell is maximally sensitive to near ultraviolet light with λmax = 380 nm. Comparison of intensity-response functions revealed that those of the mini-ommatidium are significantly steeper than those of the ocellus almost certainly as the result of neural processing in the ocellus which is absent in the mini-ommatidium.
48
Pennisi, E. "DEVELOPMENTAL BIOLOGY: Worm's Light-Sensing Proteins Suggest Eye's Single Origin." Science 306, no. 5697 (October 29, 2004): 796a—797a. http://dx.doi.org/10.1126/science.306.5697.796a.
Full text
49
Amissah, Patrick Kofi. "Amos and ‘Ghana in the Eyes of God’: a Public Theological Response to Bribery and Corruption." International Journal of Public Theology 13, no. 3 (October 7, 2019): 282–300. http://dx.doi.org/10.1163/15697320-12341579.
Full textAbstract:
AbstractThe purpose of this article is to draw upon the condemnation of bribery, corruption and miscarriage of justice to be found in the book of Amos for the sake of a public theology. The occasion for such is a bribery scandal that hit the Ghanaian judiciary. An investigative journalist presented evidence to substantiate the hitherto unsubstantiated perception that some judges in Ghana take bribes to skew judgement. The scandal is deepened through many of the judges being Christian. They attracted widespread criticism from religious leaders, both Christian and others, as well as from the wider society. The public sphere of a fair and independent judiciary was thus compromised. The argument draws upon an assessment of Amos 5:7; 10, 12 and 6:12. These texts are examined in the light of this judicial bribery and corruption scandal and thus provide an example of how the Bible can play a part in a public theology and nurture of social justice.
50
Crivelaro, R. M., R. Thiesen, M. Aldrovani, T. B. Lima, K. P. Ortêncio, I. R. M. Padua, J. M. B. Duarte, and J. L. Laus. "Electroretinography in eight species of neotropical deer." Arquivo Brasileiro de Medicina Veterinária e Zootecnia 70, no. 5 (October 2018): 1505–13. http://dx.doi.org/10.1590/1678-4162-10152.
Full textAbstract:
ABSTRACT The aim of this study was to establish normal baseline ERG values of 23 anesthetized deer belonging to 8 neotropical species (Mazama americana, Mazama nemorivaga, Mazama gouazoubira, Mazama nana, Mazama bororo, Ozotocerus bezoarticus, Odocoileus virginianus and Blastocerus dichotomus). Only right eyes were studied. Chemical restraint was performed using xylazine associated with ketamine, IM, for M. americana, M. gouazoubira, M. nemorivaga, M. nana, M. bororo, O. bezoarticus and O. virginianus. A combination of tiletamine/zolazepam diluted in xylazine 2% was used for B. dichotomus individuals. After 20min of dark adaptation, electroretinograms were obtained using a handheld electroretinography (ERG) machine using the QuickRetCheck Protocol at three different light intensities: 0.01cd.s/m2, 3cd.s/m2, and 10cd.s/m2. After light adaptation, photopic phase was recorded. A-wave amplitude recorded during pattern mixed rod/cone response in M. americana was significantly lower when compared to B. dichotomus. No other differences were observed between the species studied. ERG in Neotropical deer is applicable using a portable ERG system and did not show differences among species in relation to the retinal response at different light intensities. Therefore, the lifestyle of the species is more dictated by the selection pressure of the environment than by physiological factors.