scholarly journals The effect of blue-blocking lenses on photostress recovery times for low and high contrast chromatic and achromatic stimuli

2019 ◽  
Author(s):  
Hind Saeed Alzahrani ◽  
Sieu K. Khuu ◽  
Adiba Ali ◽  
Maitreyee Roy
Keyword(s):  
Light Exposure ◽  
Bright Light ◽  
Light Sources ◽  
High Contrast ◽  
Night Time ◽  
Low Light ◽  
Low Contrast ◽  
Light Levels ◽  
Recovery Times ◽  
Visible Wavelengths

AbstractThe selective reduction in visible wavelengths transmitted through commercially available blue-blocking lenses (BBLs) is known to influence the appearance and contrast detection of objects, particularly at low light levels which may impact the human retinal receptor response time to dynamic light changes during phostress events. In the present study, we assessed whether BBLs selectively affect photostress recovery times (PSRTs) in 12 participants for chromatic and achromatic stimuli presented under low and high contrast luminance conditions. Four types of commercially available BBLs were evaluated, and their effects on PSRTs were investigated. Our results showed that PSRTs required to detect high contrast chromatic and achromatic stimuli were unaffected by BBLs when compared to a clear control lens. However, PSRTs were significantly affected by BBLs and were longer when chromatic and achromatic stimuli were of low contrast. In addition, BBLs had the greatest impact on the PSRTs of blue coloured targets, and this was dependent on the spectral transmittance profile. These results indicate that wearing BBLs under low contrast conditions can have serious implications for visual behavior, particularly under low-light levels and in situations in which the observer is directly exposed to bright light sources. For example, during night time driving, the driver might be briefly exposed to bright lights by glancing at the headlights of a passing car. This increases the time required for vision to be restored after bright light exposure, resulting in delayed object detection, and therefore stoppage and reaction times, which might pose a safety risk for a driver.

Photoinhibition of DCMU-Enhanced Fluorescence in Lake Ontario Phytoplankton

1987 ◽  
Vol 44 (12) ◽  
pp. 2144-2154 ◽  
Author(s):  
M. Putt ◽  
G. P. Harris ◽  
R. L. Cuhel
Keyword(s):  
Vertical Mixing ◽  
Natural Populations ◽  
Bright Light ◽  
Euphotic Zone ◽  
Lake Ontario ◽  
Enhanced Fluorescence ◽  
Low Light ◽  
Light Levels ◽  
Phosphorus Status

Measurement of 1-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) enhanced fluorescence (FDCMU) suggested that photoinhibition of photosynthesis was frequently an artifact of in situ bottle incubations in Lake Ontario phytoplankton. In a seasonal study, FDCMU of all populations was depressed by bright light in an incubator. However, when the euphotic zone did not exceed the depth of the mixed layer, vertical transport of phytoplankton into either low-light or dark regions apparently allowed reversal of photoinhibition of FDCMU. Advantages of FDCMU as a bioassay of vertical mixing include rapidity of response time, ease of measurement in the field, and insensitivity of this parameter to changes in phosphorus status of the population. Because of seasonal changes in the photoadaptive response of natural populations, the rate constants and threshold light levels required to cause the response must be determined at each use if the method is to be quantitative.

The Effect of Light on Sleep and Sleep-Related Physiological Factors Among Patients in Healthcare Facilities: A Systematic Review

2019 ◽  
Vol 12 (4) ◽  
pp. 116-141
Author(s):  
Khatereh Hadi ◽  
Jennifer R. Du Bose ◽  
Young-Seon Choi
Keyword(s):  
Light Exposure ◽  
Bright Light ◽  
Light Sources ◽  
Related Factors ◽  
Healthcare Facilities ◽  
New Findings ◽  
Healthcare Environments ◽  
The Impact ◽  
Improve Patient ◽  
Bright Light Exposure

Objectives: Lighting is one of the environmental factors which can improve patient sleep in healthcare environments. Due to the high degree of variation in study designs and results on this topic, the implications have been difficult to interpret. This review consolidates studies on the impact of bright light exposure on sleep to identify lighting conditions that can be applied and researched in future healthcare environments. Methods: We searched for peer-reviewed articles on the impact of light on sleep or sleep-related outcomes in healthcare settings. We provided detailed analysis of the direct links between light and sleep, and a more cursory analysis of links between light and sleep-related factors, from 34 articles which met our inclusion criteria. Results: The current state of the literature includes evidence on how various durations and intensities of morning, midday, and evening bright light exposure, as well as whole-day light exposure interventions can improve specific aspects of sleep. Lighting interventions differed in all attributes (illuminance levels, exposure time, exposure duration, and spectral qualities) but showed promising results in improving patients’ sleep. Conclusions: Short-term bright light exposure in the morning, up to 2 hr of moderate (3,000–10,000 lux) morning exposures, up to 4 hr of moderate evening exposure, and whole-day exposures to lower illuminance levels (<3,000 lux) can improve patient sleep outcomes. Based on new findings on the mechanism through which light impacts sleep, future studies should be more specific about the spectral qualities of light sources.

scholarly journals Characterizing the modern light environment and its influence on circadian rhythms

2021 ◽  
Vol 288 (1955) ◽  
pp. 20210721
Author(s):  
Dennis Khodasevich ◽  
Susan Tsui ◽  
Darwin Keung ◽  
Debra J. Skene ◽  
Victoria Revell ◽  
...  
Keyword(s):  
Circadian Rhythms ◽  
Light Exposure ◽  
Circadian Disruption ◽  
Light Sources ◽  
Night Time ◽  
Circadian Phase ◽  
Temperature Rhythm ◽  
Four Seasons ◽  
Significant Difference ◽  
The Impact

Humans have largely supplanted natural light cycles with a variety of electric light sources and schedules misaligned with day-night cycles. Circadian disruption has been linked to a number of disease processes, but the extent of circadian disruption among the population is unknown. In this study, we measured light exposure and wrist temperature among residents of an urban area during each of the four seasons, as well as light illuminance in nearby outdoor locations. Daily light exposure was significantly lower for individuals, compared to outdoor light sensors, across all four seasons. There was also little seasonal variation in the realized photoperiod experienced by individuals, with the only significant difference occurring between winter and summer. We tested the hypothesis that differential light exposure impacts circadian phase timing, detected via the wrist temperature rhythm. To determine the influence of light exposure on circadian rhythms, we modelled the impact of morning and night-time light exposure on the timing of the maximum wrist temperature. We found that morning and night-time light exposure had significant but opposing impacts on maximum wrist temperature timing. Our results demonstrate that, within the range of exposure seen in everyday life, night-time light can delay the onset of the maximum wrist temperature, while morning light can lead to earlier onset. Our results demonstrate that humans are minimizing natural seasonal differences in light exposure, and that circadian shifts and disruptions may be a more regular occurrence in the general population than is currently recognized.

scholarly journals ANALYSIS OF APPLICATION OF CONTEMPORARY NIGHT VISION GOGGLES ON THE BASIS OF ELECTRONIC-OPTICAL CONVERTER BY THE HELICOPTER CREWS. PROSPECTIVE HELICOPTER OPTOELECTRONIC SYSTEMS OF AERIAL RECONNAISSANCE/SURVEILLANCE

2020 ◽  
pp. 50-55
Author(s):  
O. Kuzmich ◽  
V. Kuznetsov ◽  
M. Andrushko
Keyword(s):  
Search And Rescue ◽  
Night Vision ◽  
Target Acquisition ◽  
Optoelectronic System ◽  
Night Time ◽  
Low Light ◽  
Spectral Bands ◽  
Light Levels ◽  
Aerial Reconnaissance ◽  
Optoelectronic Systems

The paper studies the matters of using of night vision goggles by the helicopter crews of the State Aviation of Ukraine. The analysis of the perspective systems that can replace night vision goggles based on electronic-optical converter and provide round-the-clock and all-weather flights, landing of the helicopter on unprepared and unlit areas in poor visibility was treated. Currently, the practice of using combat and transport helicopters involves their wider use in the night-time conditions (air warfare, delivery of goods, search-and-rescue operations). Due to low light levels, until recently, most night-time target acquisition tasks have been related with the necessities of providing the artificial target illumination, but in certain instances such illumination deteriorates visibility through an lighttight, phosphorescent atmospheric shells or it just can‟t be carried out. The need for a large number of channels included in the optoelectronic system, caused by the variety of tasks that are solved by it, as well as the imperfection of each individual channel. This forces them to be combined to improve the efficiency of the optoelectronic systems themselves, so that the disadvantages of one channel are offset by the advantages of another. In fact, it is only possible way to ensure the fulfilment of combat task by combining channels operating in different spectral bands in one scheme and by combining detection devices. It can be stated that, despite the undisputed advantages of optoelectronic systems as compared to night-vision goggles, in case of the selecting for installing on a helicopter of optoelectronic systems, it should take into account the much higher cost of optoelectronic systems compared with night-vision goggles. Therefore, the rationale for installing optoelectronic systems must be determined based on the scope of the executing tasks, which are to be conducted by a specific helicopter.

scholarly journals 2. Information Storage and Integration Applied to Low-Contrast Astronomical Images

1955 ◽  
Vol 9 ◽  
pp. 676-681 ◽  
Author(s):  
G. A. Morton
Keyword(s):  
Thick Layer ◽  
Information Storage ◽  
Low Light ◽  
Observational Astronomy ◽  
Low Contrast ◽  
Black Background ◽  
Light Levels ◽  
The Earth ◽  
Astronomical Images ◽  
Contrast Image

In observational astronomy one is continually faced with the problem of interpreting faint images which are close to the limit of recognizability. The problem of threshold recognition of images at low light levels may be subdivided into two cases: (1) the limit of detectability of an image against a black background, and (2) the minimum perceptible change of illumination which can be detected at small but finite light levels. Until such time as the much-discussed space platform is launched into its orbit around the Earth, the astronomer must be content to view astronomical objects through a thick layer of relatively luminous air. Therefore, the second type of problem, namely that of a low-contrast image, is the main consideration.

Bloch's Law for Contrast Increment Detection: The Effects of Pedestal Contrast and Light Level

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 149-149
Author(s):  
R J Snowden
Keyword(s):  
Visual System ◽  
Temporal Summation ◽  
Light Level ◽  
High Light ◽  
High Contrast ◽  
Contrast Level ◽  
Low Light ◽  
Low Contrast ◽  
Temporal Characteristics ◽  
Test Grating

The duration over which contrast detection improves (Bloch's regime) decreases with increasing light level and is often thought to reflect the temporal characteristics of the visual system. There is also some evidence to suggest that the temporal characteristics of the visual system might also change with increasing contrast level (M A Georgeson, 1987 Vision Research27 765 – 780). Here we compare temporal summation for stimuli presented on a blank field or on a high contrast background. On each trial a test grating was presented for X ms with the use of a spatial-alternate forced-choice procedure. The test grating (2 cycles deg−1) was presented superimposed on a similar pedestal grating which was also present for 500 ms prior to and after the test grating. Pedestal contrasts of 0% and 32% were tested at mean luminance levels of 150 cd m−2 and 1.5 cd m−2. The results show that both increasing light level and increasing contrast level resulted in smaller temporal summation times. In the current conditions both these effects approximately halve the summation time such that for a stimulus of low light level and of low pedestal contrast the summation time was ∼60 ms; low light, high contrast ∼30 ms; high light, low contrast ∼30 ms; and high light, high contrast ∼15 ms. The results imply that the temporal response of the visual system quickens with increasing contrast.

scholarly journals Ambient bright light treatment improved proxy-rated sleep but not sleep measured by actigraphy in nursing home patients with dementia: a placebo-controlled randomised trial

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Gunnhild J. Hjetland ◽  
Eirin Kolberg ◽  
Ståle Pallesen ◽  
Eirunn Thun ◽  
Inger Hilde Nordhus ◽  
...  
Keyword(s):  
Nursing Home ◽  
Sleep Problems ◽  
Light Exposure ◽  
Bright Light ◽  
Light Treatment ◽  
Control Group ◽  
Link Type ◽  
Light Levels ◽  
Nursing Home Patients ◽  
Bright Light Treatment

Abstract Background Up to 70% of nursing home patients with dementia suffer from sleep problems. Light is the main zeitgeber to the circadian system and thus has a fundamental impact on sleep-wake behaviour. Low indoor light levels in nursing homes have been reported, and in combination with age-related reductions in light sensitivity, insufficient light exposure is likely to contribute to sleep problems in this population. Increasing daytime light exposure using bright light treatment (BLT) may represent a feasible non-pharmacological treatment for sleep problems in nursing home patients with dementia. Methods The present study reports on sleep outcomes, which are the primary outcomes of the DEM.LIGHT trial (Therapy Light Rooms for Nursing Home Patients with Dementia– Designing Diurnal Conditions for Improved Sleep, Mood and Behavioural Problems), a 24-week cluster-randomised placebo-controlled trial including 8 nursing home units and 69 resident patients. The intervention comprised ambient light of 1000 lx and 6000 K from 10:00 to 15:00, with gradually increasing and decreasing light levels prior to and following this interval, using ceiling mounted light-fixtures and light emitting diode technology. The placebo condition had continuous standard light levels (150–300 lx, ~ 3000 K). Sleep was assessed at baseline and follow-up at week 8, 16, and 24, using the proxy-rated Sleep Disorder Inventory (SDI) and actigraphy (Actiwatch II, Philips Respironics). Mixed linear models were used to evaluate intervention effects, adjusting for relevant covariates such as age, gender, number of drugs, severity of dementia, eye disease, and estimated light exposure. Results Sleep as measured by the SDI was significantly improved in the intervention group compared to the control group from baseline to week 16 (B = − 0.06, 95% CI -0.11 - -0.01, p < .05) and from baseline to week 24 (B = − 0.05, 95% CI -0.10 - -0.01, p < .05). There was no effect according to the SDI at week 8 and no significant effects in terms of actigraphically measured sleep. Conclusions Proxy-rated sleep improved among nursing home patients with dementia following 16 and 24 weeks of BLT. These improvements were not corroborated by actigraphy recordings. Trial registration ClinicalTrials.gov Identifier: NCT03357328. Registered 29 November 2017 – Retrospectively registered.

scholarly journals Purple-leaved Japanese Barberry (var. atropurpurea) Genotypes Become Visually Indistinguishable from Greenleaved Genotypes (Berberis thunbergii DC.) at Low Light Levels

2010 ◽  
Vol 28 (3) ◽  
pp. 187-189 ◽  
Author(s):  
Jonathan M. Lehrer ◽  
Mark H. Brand
Keyword(s):  
Color Change ◽  
Light Exposure ◽  
The United States ◽  
Berberis Thunbergii ◽  
Low Light ◽  
Full Sunlight ◽  
Light Levels ◽  
Japanese Barberry ◽  
Hue Angle ◽  
Anthocyanin Production

Abstract Japanese barberry (Berberis thunbergii DC.) is a popular nursery plant that has escaped from cultivation to establish invasive populations across the United States. Previous studies demonstrate that green-leaved feral plants adapt successfully to low light levels. The leaf color phenotype of purple-leaved Japanese barberry (Berberis thunbergii var. atropurpurea) seedlings grown under shaded conditions was studied to determine their appearance under low light conditions typical of wooded areas often invaded by barberry. Seedlings from B. thunbergii var. atropurpurea were grown in full sunlight and under three shade treatments (36, 50 and 72%). Seedlings were also grown in full sunlight and under two higher shade treatments (85 and 95%) in a second study. The hue angle of purple seedlings increased from a mean of 22.3 in full sun to 86.9 at 72% shade, reflecting a color change from violet-purple to green-umber. Foliage color also became more vivid and lighter as shading increased. All purple genotype seedlings appeared green when grown at 95% shade due to lack of anthocyanin production at this light exposure. Escaped barberry seedlings originating from landscape plants of var. atropurpurea may not be recognized as purple-leaved forms when they invade densely shaded woodland environments.

scholarly journals Electrochromic selective filtering of chronodisruptive visible wavelengths

PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0241900
Author(s):  
Maria Angeles Bonmati-Carrion ◽  
Javier Padilla ◽  
Raquel Arguelles-Prieto ◽  
Anna M. Österholm ◽  
John R. Reynolds ◽  
...  
Keyword(s):  
Blue Light ◽  
Ganglion Cells ◽  
Light Exposure ◽  
Control Sample ◽  
Color Naming ◽  
Internal Clock ◽  
Light Sources ◽  
Melatonin Suppression ◽  
Pupil Constriction ◽  
Visible Wavelengths

We present evidence of pupil response modification, as well as differential theoretical melatonin suppression through selective and dynamic electrochromic filtering of visible light in the 400–500 nm range to minimize chronodisruptive nocturnal blue light exposure. A lower activation of intrinsically photosensitive retinal ganglion cells (ipRGCs), the first step for light to reach a human’s internal clock, is related to melatonin secretion therefore avoiding detrimental effects of excessive blue light exposure. Pupillary Light Reflex and Color Naming were experimentally assessed under light filtered by two different coloration states (transmissive and absorptive) of these novel dynamic filters, plus an uncoated test device, in 16 volunteers. Also, different commercial light sources at illuminances ranging from 1 to 1000 lux were differentially filtered and compared in terms of theoretical melatonin suppression. Representative parameters of the pupil responses reflected lower pupil constriction when the electrochromic filters (ECFs) were switched on (absorptive state, blue light is absorbed by the filter) compared to uncoated filters (control sample), but failed to do so under transmissive state (blue light passes through the filter) indicating less activation of ipRGCs under absorptive state (although no significant differences between states was found). Out of eight colors tested, just one showed significant differences in naming between both filter states. Thus, the ECF would have some protecting effect on ipRGC activation with very limited changes in color perception. While there are some limitations of the theoretical model used, the absorptive state yielded significantly lower theoretical melatonin suppression in all those light sources containing blue wavelengths across the illuminance range tested. This would open the way for further research on biological applications of electrochromic devices.

scholarly journals Retinal transcriptome sequencing sheds light on the adaptation to nocturnal and diurnal lifestyles in raptors

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Yonghua Wu ◽  
Elizabeth A. Hadly ◽  
Wenjia Teng ◽  
Yuyang Hao ◽  
Wei Liang ◽  
...  
Keyword(s):  
Positive Selection ◽  
Transcriptome Sequencing ◽  
Bright Light ◽  
Photon Absorption ◽  
Evolutionary Analysis ◽  
Night Time ◽  
Low Light ◽  
Strong Positive Selection ◽  
Nocturnal Vision ◽  
Selection For

Abstract Owls (Strigiformes) represent a fascinating group of birds that are the ecological night-time counterparts to diurnal raptors (Accipitriformes). The nocturnality of owls, unusual within birds, has favored an exceptional visual system that is highly tuned for hunting at night, yet the molecular basis for this adaptation is lacking. Here, using a comparative evolutionary analysis of 120 vision genes obtained by retinal transcriptome sequencing, we found strong positive selection for low-light vision genes in owls, which contributes to their remarkable nocturnal vision. Not surprisingly, we detected gene loss of the violet/ultraviolet-sensitive opsin (SWS1) in all owls we studied, but two other color vision genes, the red-sensitive LWS and the blue-sensitive SWS2, were found to be under strong positive selection, which may be linked to the spectral tunings of these genes toward maximizing photon absorption in crepuscular conditions. We also detected the only other positively selected genes associated with motion detection in falcons and positively selected genes associated with bright-light vision and eye protection in other diurnal raptors (Accipitriformes). Our results suggest the adaptive evolution of vision genes reflect differentiated activity time and distinct hunting behaviors.

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