Mesopic Light Research Articles

Correlated and uncorrelated invisible temporal white noise alters mesopic rod signaling.

We determined how rod signaling at mesopic light levels is altered by extrinsic temporal white noise that is correlated or uncorrelated with the activity of one (magnocellular, parvocellular, or koniocellular) postreceptoral pathway. Rod and cone photoreceptor excitations were independently controlled using a four-primary photostimulator. Psychometric (Weibull) functions were measured for incremental rod pulses (50 to 250ms) in the presence (or absence; control) of perceptually invisible subthreshold extrinsic noise. Uncorrelated (rod) noise facilitates rod detection. Correlated postreceptoral pathway noise produces differential changes in rod detection thresholds and decreases the slope of the psychometric functions. We demonstrate that invisible extrinsic noise changes rod-signaling characteristics within the three retinogeniculate pathways at mesopic illumination depending on the temporal profile of the rod stimulus and the extrinsic noise type.

Effects of the jimpy mutation on mouse retinal structure and function.

The Jimpy mutant mouse has a point mutation in the proteolipid protein gene (plp1). The resulting misfolding of the protein leads to oligodendrocyte death, myelin destruction, and failure to produce adequately myelinated axons in the central nervous system (CNS). It is not known how the absence of normal myelination during development influences neural function. We characterized the Jimpy mouse retina to find out whether lack of myelination in the optic nerve during development has an effect on normal functioning and morphology of the retina. Optokinetic reflex measurements showed that Jimpy mice had, in general, a functional visual system. Both PLP1 antibody staining and reverse transcriptase-polymerase chain reaction for plp1 mRNA showed that plp1 is not expressed in the wild-type retina. However, in the optic nerve, plp1 is normally expressed, and consequently, in Jimpy mutant mice, myelination of axons in the optic nerve was mostly absent. Nevertheless, neither axon count nor axon ultrastructure in the optic nerve was affected. Physiological recordings of ganglion cell activity using microelectrode arrays revealed a decrease of stimulus-evoked activity at mesopic light levels. Morphological analysis of the retina did not show any significant differences in the gross morphology, such as thickness of retinal layers or cell number in the inner and outer nuclear layer. The cell bodies in the inner nuclear layer, however, were larger in the peripheral retina of Jimpy mutant mice. Antibody labeling against cell type-specific markers showed that the number of rod bipolar and horizontal cells was increased in Jimpy mice. In conclusion, whereas the Jimpy mutation has dramatic effects on the myelination of retinal ganglion cell axons, it has moderate effects on retinal morphology and function.

Determinants and standardization of mesopic visual acuity.

It is well established that visual acuity (VA) decreases with luminance but the specific factors that are responsible remain unclear. The purpose of this study was to quantify the contributions of accommodative error, pupil size, and higher-order aberrations to the decrease in VA when transitioning from photopic to mesopic light levels. Additionally, repeatability of VA at photopic and mesopic levels was measured to derive a luminance recommendation for mesopic VA testing, which can provide the standardization needed for future translational clinical studies and the widespread adoption of mesopic VA testing. Monocular VAs were assessed at one photopic and three mesopic light levels: 94, 3, 0.75, and 0.38 cd/m, with an E-ETDRS testing system in 43 normal subjects. Accommodative error, pupil size, and higher-order aberrations were obtained. Twenty subjects were retested at another visit to assess VA repeatability. The mean (±SD) logMAR (logarithm of the minimum angle of resolution) VA was -0.08 (±0.06) at 94 cd/m, 0.05 (±0.07) at 3 cd/m, 0.16 (±0.06) at 0.75 cd/m, and 0.27 (±0.09) at 0.38 cd/m. Light level and accommodative error were significantly associated with VA, and light level explained 75% of the variance. The mean differences in VAs between two visits were not significantly different from zero (p > 0.05). The coefficients of repeatability for 94, 3, 0.75, and 0.38 cd/m were 0.08, 0.11, 0.14, and 0.14 logMAR, respectively. Light level, among all other factors studied, contributes the most to the reduction in VA tested under mesopic conditions. Testing mesopic VA at 0.75 cd/m, or about 2.0 log units less than photopic testing, provides a significant and repeatable decrease in VA similar to standardized low-contrast VA testing, and therefore this level is recommended.

Vision under mesopic and scotopic illumination.

Evidence has accumulated that rod activation under mesopic and scotopic light levels alters visual perception and performance. Here we review the most recent developments in the measurement of rod and cone contributions to mesopic color perception and temporal processing, with a focus on data measured using a four-primary photostimulator method that independently controls rod and cone excitations. We discuss the findings in the context of rod inputs to the three primary retinogeniculate pathways to understand rod contributions to mesopic vision. Additionally, we present evidence that hue perception is possible under scotopic, pure rod-mediated conditions that involves cortical mechanisms.

Effect of light level on the reference frames of visual motion processing.

It is empirically known that some action-related visual tasks, which may rely on the construction of spatiotopic coordinates, are not well conducted under mesopic vision. The aim of this study was to clarify the effect of light level on the reference frame, such as retinotopic and spatiotopic coordinate bases, associated with visual motion processing. For this purpose, we used a phenomenon called visual motion priming in which the perceived direction of a directionally ambiguous test stimulus is influenced by the moving direction of a priming stimulus. Previous studies have shown that negative and positive motion priming are conspicuously observed in retinotopic and spatiotopic coordinates, respectively. In the experiments, participants made a saccade after the termination of the priming stimulus and judged the perceived direction of the test stimulus presented subsequently in retinotopic or spatiotopic coordinates at different light levels. We found that in retinotopic coordinates, negative motion priming was observed at all light levels. In spatiotopic coordinates, positive motion priming was observed at photopic and scotopic light levels, whereas the strength of motion priming was greatly reduced at mesopic light levels. These results were robust to the change in the luminance contrast or the saccadic eye movement per se. Different spatiotemporal properties of cones and rods at mesopic light levels may disturb the construction of a spatiotopic representation of motion, which leads to the disappearance of visual motion priming in spatiotopic coordinates during mesopic vision.

Reaction time measurements under mesopic light levels: Towards estimation of the visual adaptation field

The definition of the visual adaptation field in night-time driving conditions is important to implement the CIE system for mesopic photometry. For this purpose, reaction times to an achromatic circular stimulus appearing at different horizontal and vertical eccentricities were measured on uniform and non-uniform backgrounds under mesopic light levels. A large screen illuminated by three projectors providing a visual field subtending 180° × 44° was used to show the background and stimuli. The results concerning both the uniform and non-uniform fields indicate that reaction times under mesopic light levels depend on the local luminance of the visual task. The location and the luminance of the stimulus and the corresponding background luminance at that point strongly affect the reaction times in mesopic conditions. Luminance distribution of the non-uniform backgrounds also affects visual performance.

Ocular higher-order aberrations in a school children population

PurposeThe primary objective of the study was to explore the statistics of ocular higher-order aberrations in a population of primary and secondary school children. MethodsA sample of 557 children aged 10–15 years were selected from two primary and two secondary schools in Heraklion, Greece. Children were classified by age in three subgroups: group I (10.7±0.5 years), group II (12.4±0.5 years) and group III (14.5±0.5 years). Ocular aberrations were measured using a wavefront aberrometer (COAS, AMO Wavefront Sciences, USA) at mesopic light levels (illuminance at cornea was 4lux). Wavefront analysis was achieved for a 5mm pupil. Statistical analysis was carried out for the right eye only. ResultsThe average coefficient of most high-order aberrations did not differ from zero with the exception of vertical (0.076μm) and horizontal (0.018μm) coma, oblique trefoil (−0.055μm) and spherical aberration (0.018μm). The most prominent change between the three groups was observed for the spherical aberration, which increased from 0.007μm (SE 0.005) in group I to 0.011μm (SE 0.004) in group II and 0.030μm (SE 0.004) in group III. Significant differences were also found for the oblique astigmatism and the third-order coma aberrations. ConclusionsDifferences in the low levels of ocular spherical aberration in young children possibly reflect differences in lenticular spherical aberration and relate to the gradient refractive index of the lens. The evaluation of spherical aberration at certain stages of eye growth may help to better understand the underlying mechanisms of myopia development.

Contrast sensitivity measured by two different test methods in healthy, young adults with normal visual acuity.

This study reports contrast sensitivity (CS) reference values obtained by two different test methods in a strictly selected population of healthy, young adults with normal uncorrected visual acuity. Based on these results, the index of contrast sensitivity (ICS) is calculated, aiming to establish ICS reference values for this population and to evaluate the possible usefulness of ICS as a tool to compare the degree of agreement between different CS test methods. Military recruits with best eye uncorrected visual acuity 0.00 LogMAR or better, normal colour vision and age 18-25 years were included in a study to record contrast sensitivity using Optec 6500 (FACT) at spatial frequencies of 1.5, 3, 6, 12 and 18 cpd in photopic and mesopic light and CSV-1000E at spatial frequencies of 3, 6, 12 and 18 cpd in photopic light. Index of contrast sensitivity was calculated based on data from the three tests, and the Bland-Altman technique was used to analyse the agreement between ICS obtained by the different test methods. A total of 180 recruits were included. Contrast sensitivity frequency data for all tests were highly skewed with a marked ceiling effect for the photopic tests. The median ICS for Optec 6500 at 85 cd/m2 was -0.15 (95% percentile 0.45), compared with -0.00 (95% percentile 1.62) for Optec at 3 cd/m2 and 0.30 (95% percentile 1.20) FOR CSV-1000E. The mean difference between ICSFACT 85 and ICSCSV was -0.43 (95% CI -0.56 to -0.30, p<0.00) with limits of agreement (LoA) within -2.10 and 1.22. The regression line on the difference of average was near to zero (R2=0.03). The results provide reference CS and ICS values in a young, adult population with normal visual acuity. The agreement between the photopic tests indicated that they may be used interchangeably. There was little agreement between the mesopic and photopic tests. The mesopic test seemed best suited to differentiate between candidates and may therefore possibly be useful for medical selection purposes.

Possible roles of glutamate transporter EAAT5 in mouse cone depolarizing bipolar cell light responses

A remarkable feature of neuronal glutamate transporters (EAATs) is their dual functions of classical carriers and ligand-gated chloride (Cl(-)) channels. Cl(-) conductance is rapidly activated by glutamate in subtype EAAT5, which mediates light responses in depolarizing bipolar cells (DBC) in retinae of lower vertebrates. In this study, we examine whether EAAT5 also mediates the DBC light response in mouse. We took advantage of an infrared illuminated micro-injection system, and studied the effects of the EAAT blocker (TBOA) and a glutamate receptor agonist (LAP4) on the mouse electroretinogram (ERG) b-wave responses. Our results showed that TBOA and LAP4 shared similar temporal patterns of inhibition: both inhibited the ERG b-wave shortly after injection and recovered with similar time courses. TBOA inhibited the b-wave completely at mesopic light intensity with an IC50 value about 1 log unit higher than that of LAP4. The inhibitory effects of TBOA and LAP4 were found to be additive in the photopic range. Furthermore, TBOA alone inhibited the b-wave in the cone operative range in knockout mice lacking DBCRs at a low concentration that did not alter synaptic glutamate clearance activity. It also produced a stronger inhibition than that of LAP4 on the cone-driven b-wave measured with a double flash method in wildtype mice. These electrophysiological data suggest a significant role for EAAT5 in mediating cone-driven DBC light responses. Our immunohistochemistry data indicated the presence of postsynaptic EAAT5 on some DBCCs and some DBCRs, providing an anatomical basis for EAAT5's role in DBC light responses.

Light propagation in burrows of subterranean rodents: tunnel system architecture but not photoreceptor sensitivity limits light sensation range

AbstractAbout 300 species of mammals have adapted to the dark underground ecotope. Despite a long history of underground existence, many strictly subterranean species have retained structurally normal eyes possessing the capability of image‐forming vision. Moreover, their retinae often feature high cone proportions, an indication of conserved photopic (daylight) vision. Although it has been suggested that low acuity vision plays an important role in predator avoidance, not a single attempt to measure light conditions in burrows has been made so far. Here, we report the first measurements of light propagation in an illuminated artificial tunnel and in experimentally opened burrows ofAnsell's mole‐rat,Fukomys anselliin its natural habitat. Only about 0.2–2.5% of the ambient visible light entered the opened burrow. Light intensity attenuated quickly and reached mesopic light levels (at which both cones and rods contribute to vision) within a few centimetres from the burrow opening; scotopic light levels (at which only rods operate) were estimated to be reached at one to a few metres from the opening. Thus, although cones may hypothetically contribute to vision for up to a few metres, they play an indispensable role only in the immediate vicinity of a breach, where rods are fully saturated. Rod‐mediated light sensation in straight tunnels seems to be possible over distances much longer than 100 m, implying that it is the burrow architecture (tortuosity and branching) what limits light sensation under natural conditions. These findings clearly show that light propagating within a breached burrow may serve as a reliable cue providing information about the site of potential predation risk. Both rods and cones contribute to this signalling. The fact that blue light propagated much less efficiently than longer wavelength light suggests that the short‐wave‐sensitive opsin dominance in theAfrican mole‐rats represents a non‐adaptive feature that seems to be associated with arrested cone development.

Assessing Rod, Cone, and Melanopsin Contributions to Human Pupil Flicker Responses

We determined the relative contributions of rods, cones, and melanopsin to pupil responses in humans using temporal sinusoidal stimulation for light levels spanning the low mesopic to photopic range. A four-primary Ganzfeld photostimulator controlled flicker stimulations at seven light levels (-2.7 to 2 log cd/m(2)) and five frequencies (0.5-8 Hz). Pupil diameter was measured using a high-resolution eye tracker. Three kinds of sinusoidal photoreceptor modulations were generated using silent substitution: rod modulation, cone modulation, and combined rod and cone modulation in phase (experiment 1) or cone phase shifted (experiment 2) from a fixed rod phase. The melanopsin excitation was computed for each condition. A vector sum model was used to estimate the relative contribution of rods, cones, and melanopsin to the pupil response. From experiment 1, the pupil frequency response peaked at 1 Hz at two mesopic light levels for the three modulation conditions. Analyzing the rod-cone phase difference for the combined modulations (experiment 2) identified a V-shaped response amplitude with a minimum between 135° and 180°. The pupil response phases increased as cone modulation phase increased. The pupil amplitude increased with increasing light level for cone, and combined (in-phase rod and cone) modulation, but not for the rod modulation. These results demonstrate that cone- and rod-pathway contributions are more predominant than melanopsin contribution to the phasic pupil response. The combined rod, cone, and melanopsin inputs to the phasic state of the pupil light reflex follow linear summation.

Comparative Evaluation of Light-Emitting Diode Cap Lamps With an Emphasis on Visual Performance in Mesopic Lighting Conditions

Conducted at the National Institute for Occupational Safety and Health's (NIOSH) Office of Mine Safety and Health Research, the experiment described in this paper is part of ongoing mine illumination research designed to explore the benefits of solid-state lighting technologies when applied to the underground mining industry. This experiment involves the comparative evaluation of cap lamps with similar spectral power distributions, focusing on the electrical and battery discharge characteristics, with a secondary objective being the benefits gained through alternative light beam distributions. NIOSH researchers conducted the investigation by comparing three commercially available light-emitting diode cap lamps and an NIOSH prototype cap lamp at varying power settings. Visual performance for the detection of hazards was quantified by recording times of detection for finding rotating targets in the peripheral field of view and objects representing trip and fall hazards on the ground. The NIOSH prototype cap lamp resulted in improvements ranging from 15% to 43% for peripheral motion detection time and 5%-23% for slip, trip, and fall object detection time, respectively, as compared with the referent incandescent cap lamp.

Opposed interaction of rods and long-wavelength-sensitive cones under mesopic lighting conditions

Opposed interaction of rods and long-wavelength-sensitive cones under mesopic lighting conditions

Visual motion priming reveals why motion perception deteriorates during mesopic vision

We know empirically that the perception of moving objects deteriorates under mesopic vision, in which both rods and cones operate. The purpose of this study was to examine the cause of this degradation. We utilized a phenomenon called visual motion priming, in which the perceived direction of a directionally ambiguous test stimulus is influenced by the moving direction of a preceding stimulus. The spatial distances between the priming and the test stimuli were varied. At mesopic light levels, a stimulus that is presented at the central retina is presumably processed by the cone system, while a stimulus that is presented at the peripheral retina is processed by the rod system (Raphael & MacLeod, 2011). Subjects judged the perceived direction of 180° phase-shifted sine-wave grating that was followed by a smoothly drifting priming stimulus under different retinal illuminances. We found that, under mesopic conditions, the strength of motion priming was greatly reduced when the priming and test stimuli were presented separately at the center and the periphery, respectively. In contrast, motion priming was perceived in most of the trials under photopic and scotopic conditions or when both the priming and test stimuli were presented at the central retina under mesopic conditions. When the priming and test stimuli temporally overlapped, motion priming was conspicuous irrespective of the retinal illuminance. These results suggest that the incompleteness in the integration of signals that was induced by the temporal delay of rod pathways caused the degradation of motion perception under mesopic vision.

The Impact on Vision of Aspheric to Spherical Monofocal Intraocular Lenses in Cataract Surgery: A Systematic Review with Meta-analysis

<h3>Purpose</h3> To provide a summary of the impact on vision of an aspheric intraocular lens (IOL) compared with a spherical IOL in cataract surgery. <h3>Design</h3> Systematic review with meta-analysis. <h3>Participants</h3> Patients from published randomized controlled trials (RCTs) of cataract surgery with aspheric compared with spherical monofocal IOL implantation. <h3>Methods</h3> We systematically searched the peer-reviewed literature in MEDLINE, EMBASE, Web of Science, BIOSIS, and the Cochrane Library according to the Cochrane Collaboration method to identify relevant RCTs. The inclusion criteria were RCTs on cataract surgery comparing the use of aspheric versus spherical IOL implantation that assessed visual acuity, contrast sensitivity, or quality of vision. The effects were calculated as mean differences or standardized mean differences (Hedges' g) and pooled using random-effect models. <h3>Main Outcome Measures</h3> Best-corrected visual acuity (BCVA), contrast sensitivity, and subjective perception of the quality of vision. <h3>Results</h3> Forty-three studies provided data and were included, comprising 2076 eyes implanted with aspheric IOLs and 2034 eyes implanted with spherical IOLs. The BCVA showed a significant difference for aspheric IOLs (−0.01 logarithm of the minimum angle of resolution; 95% confidence interval [CI], −0.02 to −0.00). For contrast sensitivity, a significant advantage for aspheric IOLs was found under photopic and mesopic light conditions (photopic: Hedges' g 0.42, 95% CI 0.24–0.61 (3 cycles per degree [cpd]) to 0.53, 95% CI 0.33–0.73 (12 cpd); mesopic: Hedges' g 0.49, 95% CI 0.23–0.75 (1.5 cpd) to 0.76, 95% CI 0.52–1.00 (18 cpd)). Questionnaires targeting the subjective perception of quality of vision yielded less conclusive results. <h3>Conclusions</h3> Overall, a patient may achieve better contrast sensitivity with an aspheric IOL than with a spherical IOL, especially under dim light. There was no clinically relevant difference in BCVA between aspheric and spherical IOL implantation. The findings on the subjective perception of visual quality were heterogeneous with no clear result favoring either option. <h3>Financial Disclosure(s)</h3> The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Inferred L/M cone opsin polymorphism of ancestral tarsiers sheds dim light on the origin of anthropoid primates

Tarsiers are small nocturnal primates with a long history of fuelling debate on the origin and evolution of anthropoid primates. Recently, the discovery of M and L opsin genes in two sister species, Tarsius bancanus (Bornean tarsier) and Tarsius syrichta (Philippine tarsier), respectively, was interpreted as evidence of an ancestral long-to-middle (L/M) opsin polymorphism, which, in turn, suggested a diurnal or cathemeral (arrhythmic) activity pattern. This view is compatible with the hypothesis that stem tarsiers were diurnal; however, a reversion to nocturnality during the Middle Eocene, as evidenced by hyper-enlarged orbits, predates the divergence of T. bancanus and T. syrichta in the Late Miocene. Taken together, these findings suggest that some nocturnal tarsiers possessed high-acuity trichromatic vision, a concept that challenges prevailing views on the adaptive origins of the anthropoid visual system. It is, therefore, important to explore the plausibility and antiquity of trichromatic vision in the genus Tarsius. Here, we show that Sulawesi tarsiers (Tarsius tarsier), a phylogenetic out-group of Philippine and Bornean tarsiers, have an L opsin gene that is more similar to the L opsin gene of T. syrichta than to the M opsin gene of T. bancanus in non-synonymous nucleotide sequence. This result suggests that an L/M opsin polymorphism is the ancestral character state of crown tarsiers and raises the possibility that many hallmarks of the anthropoid visual system evolved under dim (mesopic) light conditions. This interpretation challenges the persistent nocturnal-diurnal dichotomy that has long informed debate on the origin of anthropoid primates.

Road Lighting Design from the Point of View of Mesopic Vision(&lt;Special Issue&gt;Efficient and Safe Lighting Based on the Spectral Sensitivity of Human Vision at Mesopic Light Levels)

In recent years, LED has become widespread in the world as light sources for outdoor lighting. Replacing existing light sources to LED, the energy consumption is greatly reduced. From CIE191 and other studies, under low light(mesopic) conditions, people can see brighter and more quickly detect objects which are illuminated by the lamp which has more shortwavelength components. However, this is the effect in peripheral vision, The most important light coming from the viewed object activates the very center of the retina known as the fovea. The rod response does not contribute to the important visual task of direct object recognition. Therefore, (1) the recommended light levels should be specified standard photopic photometric quantities and (2) the lamp which has more shortwavelength components is effective under mesopic lighting conditions for outdoor lighting such as a pedestrian in a roadway. In this paper, discuss technical challenges to mesopic vision technology into outdoor lighting.

What is CIE's Recommended System for Mesopic Photometry?(&lt;Special Issue&gt;Efficient and Safe Lighting Based on the Spectral Sensitivity of Human Vision at Mesopic Light Levels)

What is CIE's Recommended System for Mesopic Photometry?(&lt;Special Issue&gt;Efficient and Safe Lighting Based on the Spectral Sensitivity of Human Vision at Mesopic Light Levels)

How do Color and Brightness Change in the Mesopic Illuminance Level?(&lt;Special Issue&gt;Efficient and Safe Lighting Based on the Spectral Sensitivity of Human Vision at Mesopic Light Levels)

How do Color and Brightness Change in the Mesopic Illuminance Level?(&lt;Special Issue&gt;Efficient and Safe Lighting Based on the Spectral Sensitivity of Human Vision at Mesopic Light Levels)

What are Remaining Issues for Implementation of the CIE Mesopic Photometry System?(&lt;Special Issue&gt;Efficient and Safe Lighting Based on the Spectral Sensitivity of Human Vision at Mesopic Light Levels)

What are Remaining Issues for Implementation of the CIE Mesopic Photometry System?(&lt;Special Issue&gt;Efficient and Safe Lighting Based on the Spectral Sensitivity of Human Vision at Mesopic Light Levels)