Practical Advice on Measuring and Applying Light for Laboratory Mammals.

Light is recognized as an important component of the environment for laboratory animals. It supports vision, sets the phase of circadian clocks, and drives wide-ranging adjustments in physiological and behavioral state. Manipulating light is meanwhile a key experimental approach in the fields of vision science and chronobiology. Nevertheless, until recently, there has been no consensus on methods for quantifying light as experienced by laboratory animals. Widely adopted practices employ metrics such as illuminance (units = lux) that are designed to quantify light as experienced by human observers. These weight energy across the spectrum according to a spectral sensitivity profile for human vision that is not widely replicated for non-human species. Recently, a Consensus View was published that proposes methods of light measurement and standardization that take account of these species-specific differences in wavelength sensitivity. Here, we draw upon the contents of that consensus to provide simplified advice on light measurement in laboratory mammal experimentation and husbandry and quantitative guidance on what constitutes appropriate lighting for both visual and circadian function.

Towards an evidence-based integrative lighting score: a proposed multi-level approach.

Background: Human circadian clocks are synchronized daily with the external light-dark cycle and entrained to the 24-hour day. There is increasing evidence that a lack of synchronization and circadian entrainment can lead to adverse health effects. Beyond vision, light plays a critical role in modulating many so-called non-visual functions, including sleep-wake cycles, alertness, mood and endocrine functions. To assess (and potentially optimize) the impact of light on non-visual functions, it is necessary to know the exact 'dose' (i.e. spectral irradiance and exposure duration at eye level) of 24-hour light exposures, but also to include metadata about the lighting environment, individual needs and resources.Problem statement: To address this problem, a new assessment tool is needed that uses existing metrics to provide metadata and information about light quality and quantity from all sources. In this commentary, we discuss the need to develop an evidence-based integrative lighting score that is tailored to specific audiences and lighting environments. We will summarize the most compelling evidence from the literature and outline a future plan for developing such a lighting score using internationally accepted metrics, stakeholder and user feedback.Conclusion: We propose a weighting system that combines light qualities with physiological and behavioral effects, and the use of mathematical modelling for an output score. Such a scoring system will facilitate a holistic assessment of a lighting environment, integrating all available light sources.

To assess the impact of light on non-visual functions, it is essential to know the exact 'dose' of 24-hour light exposures and metadata about the lighting environment and the individual.There is to date no measurement method available that allows a holistic assessment of a lighting environment for visual and non-visual aspects in humans.We discuss the need for an evidence-based integrative lighting score and outline a plan for its development.An evidence-based integrative lighting score, which includes a weighting system to combine light qualities with physiological and behavioral effects, will only be possible by joining forces, knowledge, and methodologies from many disciplines.Such a score entails the potential to sustainably assess, improve and maintain optimized lighting environments that promote the health and productivity of any cohort over the long term.

The effect of illumination on the visibility of steps and ramps for people with low vision.

SIGNIFICANCE: Poor visibility of indoor features such as steps and ramps can pose mobility hazards for people with low vision. For purposes of architectural design, it is important to understand how design parameters such as the illumination level of an indoor space affect the visibility of steps and ramps. PURPOSE: This study was aimed to examine the effect of typical variation in photopic illumination level in an indoor space on the visibility of steps and ramps for individuals with low vision. METHODS: Steps and ramps were constructed in a large windowless room illuminated by overhead lights. Subjects with low vision completed a 5-alternative forced choice task to recognize the targets at three levels of photopic illumination, i.e., 800, 80, and 8 lux, and gave confidence ratings about their judgments on a 5-point scale. Acuities and contrast sensitivities of the subjects were also measured at each illumination level. For comparison, a group of normally sighted subjects with simulated acuity reduction also completed the step-and-ramp recognition task. RESULTS: For both groups of subjects, recognition accuracy was not affected by illumination level. For subjects with low vision, however, there was a significant effect of illumination level on confidence rating: subjects became more confident about their judgments with increasing illumination. There was also a weak effect of illumination level on acuity and contrast sensitivity, both worsening with decreasing illumination. Recognition performance was best predicted by contrast sensitivity, whereas confidence was best predicted by visual acuity. CONCLUSIONS: Illumination variation over a typical photopic range in an indoor space had minimal effect on the objective visibility of steps and ramps for people with low vision. However, illumination level affected subjects' confidence in hazard recognition. Design decisions on parameters such as illumination should consider the consequences on both the objective and the subjective accessibility of a space.

Advancing driver fatigue detection in diverse lighting conditions for assisted driving vehicles with enhanced facial recognition technologies.

Against the backdrop of increasingly mature intelligent driving assistance systems, effective monitoring of driver alertness during long-distance driving becomes especially crucial. This study introduces a novel method for driver fatigue detection aimed at enhancing the safety and reliability of intelligent driving assistance systems. The core of this method lies in the integration of advanced facial recognition technology using deep convolutional neural networks (CNN), particularly suited for varying lighting conditions in real-world scenarios, significantly improving the robustness of fatigue detection. Innovatively, the method incorporates emotion state analysis, providing a multi-dimensional perspective for assessing driver fatigue. It adeptly identifies subtle signs of fatigue in rapidly changing lighting and other complex environmental conditions, thereby strengthening traditional facial recognition techniques. Validation on two independent experimental datasets, specifically the Yawn and YawDDR datasets, reveals that our proposed method achieves a higher detection accuracy, with an impressive 95.3% on the YawDDR dataset, compared to 90.1% without the implementation of Algorithm 2. Additionally, our analysis highlights the method's adaptability to varying brightness levels, improving detection accuracy by up to 0.05% in optimal lighting conditions. Such results underscore the effectiveness of our advanced data preprocessing and dynamic brightness adaptation techniques in enhancing the accuracy and computational efficiency of fatigue detection systems. These achievements not only showcase the potential application of advanced facial recognition technology combined with emotional analysis in autonomous driving systems but also pave new avenues for enhancing road safety and driver welfare.

Urban house finches are more resistant to the effects of artificial light at night.

Rapid urbanization of habitats alters the physical, chemical, auditory, and photic environments of human and wild animal inhabitants. One of the most widespread transformations is caused by artificial light at night (ALAN), but it is not clear the extent to which individuals acclimate to such rapid environmental change. Here, we tested the hypothesis that urban birds show increased resistance to harmful behavioral, parasitological, and physiological effects of ALAN. We captured house finches (Haemorhous mexicanus), a bird that commonly inhabits cities and their natural surroundings, from two urban and two rural sites in Phoenix, Arizona, USA, which differ by both degree of urbanization and by multiple orders of magnitude in ALAN intensity, and placed them in a common garden laboratory setting. We exposed half of the birds from each habitat type to ecologically relevant levels of night lighting during the subjective night and found that, while ALAN exposure reduced sleep in both urban and rural birds, ALAN-exposed urban birds were able to sleep longer than ALAN-exposed rural birds. We also found that ALAN exposure increased the proliferation rate of an intestinal coccidian parasite (Isospora spp.) in both urban and rural birds, but that the rate of proliferation was lower in urban relative to rural birds. We found that night lighting suppressed titers of feather corticosterone in rural but not urban birds, suggesting that light impairs HPA function through chronic stress or suppression of its circadian rhythmicity, and that urban birds were again resistant to this effect. Mediation analyses show that the effect of ALAN exposure in rural birds was significantly sleep-mediated for feather corticosterone but not coccidiosis, suggesting a diversity of mechanisms by which ALAN alters physiology. We contribute further evidence that animals from night-lit habitats can develop resistance to ALAN and its detrimental effects.

Detecting Early-Stage Pressure Injury in Patients With Dark Skin Tones Using an Enhanced Physical Assessment Technique and Halogen Lighting.

PURPOSE: The purpose of this quality improvement project was to identify stage 1 pressure injuries (PIs) in patients with darker skin tones using an enhanced skin assessment (Skin Assessment for Dark Skin, SADS) and halogen lighting. PARTICIPANTS AND SETTING: This quality improvement project was conducted on 3 units at a large university teaching hospital in Southeast Michigan. The project was originally designed so that participating patients were identified by bedside nurses as having sufficient melanin to obscure blanching on the hand/forearm using regular lighting, but this goal was not met. Data analysis is based on patients who self-identified as African American or Black, Native Hawaiian or Pacific Islander, Asian, American Indian, and Native Alaskan. Bedside nurses participating in this project were also asked to complete a questionnaire describing their knowledge and experiences with this project and assessment of early-stage PI in patients with darker skin tones. APPROACH: The Iowa Model of Evidence-Based Practice was used to guide this quality improvement initiative. Following a trigger event, we reviewed pertinent literature and developed an enhanced technique for assessing patients with darker skin tones that involved use of halogen lighting (SADS) and documentation of findings. We selected units from our facility and taught nurses to apply the SADS approach. Data from the electronic medical record and a survey of participating nurses were used to compare findings before and after project implementation. Comparisons were based on descriptive data analysis. OUTCOMES: Following implementation of the enhanced physical assessment, the participating units experienced a 6% decrease in the total number of facility-acquired PIs during the implementation period. IMPLICATIONS FOR PRACTICE: The enhanced physical assessment, when paired with halogen lighting, enhanced identification of stage 1 PI in persons with dark skin. The assessment method was easy to teach, learn, and can be performed at the bedside as part of a shift assessment which routinely includes inspection of skin.

Cuttlefish adopt disruptive camouflage under dynamic lighting.

Many animals avoid detection or recognition using camouflage tailored to the visual features of their environment.1,2,3 The appearance of those features, however, can be affected by fluctuations in local lighting conditions, making them appear different over time.4,5 Despite dynamic lighting being common in many terrestrial and aquatic environments, it is unknown whether dynamic lighting influences the camouflage patterns that animals adopt. Here, we test whether a common form of underwater dynamic lighting, consisting of moving light bands that can create local fluctuations in the intensity of light ("water caustics"), affects the camouflage of cuttlefish (Sepia officinalis). Owing to specialized pigment cells (chromatophores) in the skin,6 these cephalopod mollusks can dynamically adjust their body patterns in response to features of their visual scene.7,8,9 Although cuttlefish resting on plain or patterned backgrounds usually expressed uniform or disruptive body patterns, respectively,10,11,12 exposure to these backgrounds in dynamic lighting induced stronger disruptive patterns regardless of the background type. Dynamic lighting increased the maximum contrast levels within scenes, and these maximum contrast levels were associated with the degree of cuttlefish disruptive camouflage. This adoption of disruptive camouflage in dynamically lit scenes may be adaptive, reducing the likelihood of detection, or alternatively, it could represent a constraint on visual processing.

Development and Assessment of Multiple Illumination Color Fourier Ptychographic Microscopy for High Throughput Sample Digitization.

In this study, we proposed a multiplexed color illumination strategy to improve the data acquisition efficiency of Fourier ptychography microscopy (FPM). Instead of sequentially lighting up one single channel LED, our method turns on multiple white light LEDs for each image acquisition via a color camera. Thus, each raw image contains multiplexed spectral information. An FPM prototype was developed, which was equipped with a 4×/0.13 NA objective lens to achieve a spatial resolution equivalent to that of a 20×/0.4 NA objective lens. Both two- and four-LED illumination patterns were designed and applied during the experiments. A USAF 1951 resolution target was first imaged under these illumination conditions, based on which MTF curves were generated to assess the corresponding imaging performance. Next, H&E tissue samples and analyzable metaphase chromosome cells were used to evaluate the clinical utility of our strategy. The results show that the single and multiplexed (two- or four-LED) illumination results achieved comparable imaging performance on all the three channels of the MTF curves. Meanwhile, the reconstructed tissue or cell images successfully retain the definition of cell nuclei and cytoplasm and can better preserve the cell edges as compared to the results from the conventional microscopes. This study initially validates the feasibility of multiplexed color illumination for the future development of high-throughput FPM scanning systems.

The Working Environment in Primary Healthcare Outpatient Facilities: Assessment of Physical Factors and Health Professionals' Perceptions of Working Environment Conditions.

The objectives of this study were to assess the adequacy of physical parameters/factors (temperature, relative humidity, noise, and illuminance levels) of the work environment in PHC facilities, to evaluate the association between the adequacy of these measured physical parameters and the physical characteristics of the PHC facilities and their surroundings and to assess the association between health professionals' perceptions about exposure to physical risks in the PHC work environment and the adequacy of physical parameters measured in the same facilities. The study monitored 23 PHC facilities in southern Brazil and interviewed 210 health professionals. Data analysis involved Pearson's chi-square, Fisher's exact test, Spearman's correlation, and multivariate linear regression analysis was used to control for confounding factors. The significance level was set at 5% (p ≤ 0.05). The combination of temperature and relative humidity presented thermal comfort levels outside the adopted criteria for adequacy in consultation (outdoor relative humidity, p = 0.013) and procedure rooms (front door open, p = 0.034). Inadequate sound comfort (noise) levels in the morning shift were found in the vaccination (front door open, p = 0.021) and consultation rooms (movement of people, p = 0.016). In PHC facilities where reception rooms had insufficient lighting, internal curtains were opened less frequently (p = 0.047). The analysis of health professionals' perceptions of physical factors demonstrated that physicians more frequently perceive the physical risk of temperature and humidity (p = 0.044). The higher the number of nurses (p = 0.004) and oral health technicians in the PHC facilities (p = 0.031), the greater the general percentage of adequacy of monitored physical parameters. It was also confirmed that the higher the perception of moderate or severe physical risk among health professionals, the lower the general percentage of the adequacy of the physical parameters of the work environment of the PHC facilities evaluated (rs = -0.450, p = 0.031). This study's evidence contributes to a better understanding of physical conditions and future occupational interventions to ensure the comfort, safety, and well-being of PHC workers.

Daylight and Electric Lighting in Primary and Secondary School Classrooms in the UK-An Observational Study.

Only a few recent studies report direct assessment or monitoring of light levels in the indoor learning environment, and no consensus exists on minimum exposures for children's health. For instance, myopia is a common progressive condition, with genetic and environmental risk factors. Reduced daylight exposure, electric lighting changes, increased near-work for school children, greater academic focus, and use of display screens and white boards may have important detrimental influences. Published assessment methods had varied limitations, such as incomplete compliance from participants wearing light loggers for extended periods. Climate-Based Daylight Modelling is encouraged in UK school design, but design approaches are impractical for post-occupancy assessments of pre-existing classrooms or ad hoc modifications. In this study, we investigated the potential for direct assessment and monitoring of classroom daylight and lighting measurements. Combined with objective assessments of outdoor exposures and class time use, the classroom data could inform design and light exposure interventions to reduce the various health impacts of inadequate daylight exposure. The relevant environmental measure for myopia depends on the hypothesized mechanism, so the illuminance, spectral distribution, and temporal light modulation from the electric lighting was also assessed.

Adaptation of indoor ornamental plants to various lighting levels in growth chambers simulating workplace environments.

Despite the growing interest in indoor greenery and its positive effects on occupants' well-being, there is limited knowledge on the optimal light levels for indoor plants that ensure energy efficiency and sustainable growth. This study explored the survival of ornamental plants under low-light conditions typical of indoor workplaces without daylight and investigated the impact of increased light intensity or extended day length on their growth. Three species of foliage plants (Epipremnum aureum, Pachira aquatica, and Rhaphidophora tetrasperma) were cultivated in growth chambers with three different lighting schemes. The results showed that plants sustained growth with 6.8 µmol m-2 s-1 white LED light for 9 h/day, suggesting that extra lighting might not be necessary for shade-tolerant species in offices. In this environment, plants maintained efficient photosynthesis under low illumination by increasing their specific leaf area. Elevating the light to 20.1 µmol m-2 s-1 and extending the day length to 18 h/day enhanced the plants' relative growth rate. Climbing plants allocated more biomass to stems, resulting in a lower leaf weight ratio and noticeably altering their appearance. This study demonstrates that customized lighting strategies effectively support indoor greening goals, like adjusting intensity for energy savings or adding light for greening large spaces.

Reduction of coastal lighting decreases seabird strandings.

Artificial light at night (ALAN) is negatively impacting numerous species of nocturnally active birds. Nocturnal positive phototaxis, the movement towards ALAN, is exhibited by many marine birds and can result in stranding on land. Seabird species facing major population declines may be most at risk. Leach's Storm-Petrels (Hydrobates leucorhous) are small, threatened seabirds with an extensive breeding range in the North Atlantic and North Pacific Oceans. The Atlantic population, which represents approximately 40-48% of the global population, is declining sharply. Nocturnal positive phototaxis is considered to be a key contributing factor. The Leach's Storm-Petrel is the seabird species most often found stranded around ALAN in the North Atlantic, though there is little experimental evidence that reduction of ALAN decreases the occurrence of stranded storm-petrels. During a two-year study at a large, brightly illuminated seafood processing plant adjacent to the Leach's Storm-Petrel's largest colony, we compared the number of birds that stranded when the lights at the plant were on versus significantly reduced. We recorded survival, counted carcasses of adults and juveniles, and released any rescued individuals. Daily morning surveys revealed that reducing ALAN decreased strandings by 57.11% (95% CI: 39.29% - 83.01%) per night and night surveys revealed that reducing ALAN decreased stranding of adult birds by 11.94% (95% CI: 3.47% - 41.13%) per night. The peak stranding period occurred from 25 September to 28 October, and 94.9% of the birds found during this period were fledglings. These results provide evidence to support the implementation of widespread reduction and modification of coastal artificial light as a conservation strategy, especially during avian fledging and migration periods.

Randomized trial comparing the effects of a 3D head-up system and microscope eyepiece-assisted simulated vitrectomy with intraocular illumination on the ocular surface of an operator.

BACKGROUND: To compare the effects of a 3D head-up system and microscope eyepiece-assisted simulated vitrectomy intraocular illumination on the ocular surface of an operator. METHODS: This was a prospective randomized controlled study. According to the application system, thirty ophthalmic operators (60 eyes) were randomly divided into 3D and eyepiece groups. Under different intensities of intraocular illumination, operators in both groups viewed the fundus model through a 3D display screen or microscopic eyepiece for 2 h. Objective examinations and a subjective symptom questionnaire were used immediately after the test to evaluate the ocular surface of the operators. Objective examinations included nonintrusion tear meniscus height (NIKTMH), nonintrusion break-up time (NIKBUT), and bulbar redness and strip meniscometry tube (SMTube) measurements. Statistical analyses were performed by using SPSS 26.0 software. RESULTS: After the test, the NIKTMH, NIKBUT and SMTube measurements decreased; however, the degree of change varied among the groups of different systems. The differences between the 3D group and the eyepiece group in NIKTMH measurements, SMTube measurements, subjective symptom scores (eye dryness, difficulty focusing, and cervical pain), and light intensity reaching the ocular surface of the operators were statistically significant (P < 0.05). All of the objective and subjective tests showed that the 3D group had fewer effects on the NIKTMH and SMTube measurements, and the subjective comfort of the 3D group was greater. CONCLUSION: For both 3D screens and eyepieces, simulated vitrectomy with intraocular illumination for two hours can lead to discomfort and abnormalities in the operator's ocular surface; however, these abnormalities are less severe in the 3D group. TRIAL REGISTRATION: This trial was registered on December 22, 2022, at the Chinese Clinical Trials Registry with NO. ChiCTR2200066989.

High-speed eye tracking based on a synchronized imaging mechanism by a dual-ring infrared lighting source.

It is a challenge for conventional monocular-camera single-light source eye-tracking methods to achieve high-speed eye tracking. In this work, a dual-ring infrared lighting source was designed to achieve bright and dark pupils in high speed. The eye-tracking method used a dual-ring infrared lighting source and synchronized triggers for the even and odd camera frames to capture bright and dark pupils. A pupillary corneal reflex was calculated by the center coordinates of the Purkinje spot and the pupil. A map function was established to map the relationship between the pupillary corneal reflex and gaze spots. The gaze coordinate was calculated based on the mapping function. The average detection time of each gaze spot was 3.76 ms.

Relative importance of intensity and spectrum of artificial light at night in disrupting behavior of a nocturnal rodent.

The influence of light spectral properties on circadian rhythms is of substantial interest to laboratory-based investigation of the circadian system and to field-based understanding of the effects of artificial light at night. The trade-offs between intensity and spectrum regarding masking behaviors are largely unknown, even for well-studied organisms. We used a custom LED illumination system to document the response of wild-type house mice (Mus musculus) to 1-h nocturnal exposure of all combinations of four intensity levels (0.01, 0.5, 5 and 50 lx) and three correlated color temperatures (CCT; 1750, 1950 and 3000 K). Higher intensities of light (50 lx) suppressed cage activity substantially, and consistently more for the higher CCT light (91% for 3000 K, 53% for 1750 K). At the lowest intensity (0.01 lx), mean activity was increased, with the greatest increases for the lowest CCT (12.3% increase at 1750 K, 3% increase at 3000 K). Multiple linear regression confirmed the influence of both CCT and intensity on changes in activity, with the scaled effect size of intensity 3.6 times greater than that of CCT. Activity suppression was significantly lower for male than for female mice. Assessment of light-evoked cFos expression in the suprachiasmatic nucleus at 50 lx showed no significant difference between high and low CCT exposure. The significant differences by spectral composition illustrate a need to account for light spectrum in circadian studies of behavior, and confirm that spectral controls can mitigate some, but certainly not all, of the effects of light pollution on species in the wild.

Association between outdoor light at night exposure and executive function in Chinese children.

BACKGROUND: Recent evidences highlight the potential impact of outdoor Light at Night (LAN) on executive function. However, few studies have investigated the association between outdoor LAN exposure and executive function. METHODS: We employed data from 48,502 Chinese children aged 5-12 years in a cross-sectional study conducted in Guangdong province during 2020-2021, to examine the association between outdoor LAN and executive function assessed using the validated parent-completed Behavior Rating Inventory of Executive Function. We assessed children's outdoor LAN exposure using the night-time satellite images based on the residential addresses. We used generalized linear mixed models to estimate the association between outdoor LAN exposure and executive function scores and executive dysfunction. RESULTS: After adjusting for potential covariates, higher quintiles of outdoor LAN exposure were associated with poorer executive function. Compared to the lowest quintile (Q1), all higher quintiles of exposure showed a significant increased global executive composite (GEC) score with ß (95% confidence intervals, CI) of 0.58 (0.28, 0.88) in Q2, 0.59 (0.28, 0.9) in Q3, 0.85 (0.54, 1.16) in Q4, and 0.76 (0.43, 1.09) in Q5. Higher quintiles of exposure were also associated with higher risks for GEC dysfunction with odd ratios (ORs) (95% CI) of 1.34 (1.18, 1.52) in Q2, 1.40 (1.24, 1.59) in Q3, 1.40 (1.23, 1.59) in Q4, and 1.39 (1.22, 1.58) in Q5. And stronger associations were observed in children aged 10-12 years. CONCLUSIONS: Our study suggested that high outdoor LAN exposure was associated with poor executive function in children. These findings suggested that future studies should determine whether interventions to reduce outdoor LAN exposure can have a positive effect on executive function.

Real-ambient bedroom light at night increases systemic inflammation and disrupts circadian rhythm of inflammatory markers.

BACKGROUND: Exposure to light at night (LAN) has been associated with multiple adverse health outcomes. However, evidence is limited regarding the impacts of LAN exposure on human inflammation. OBJECTIVES: To examine the association between real-ambient bedroom LAN exposure with systemic inflammation and circadian rhythm of inflammatory markers. METHODS: Using data from a prospective cohort study of Chinese young adults. At baseline, bedroom LAN exposure was measured with a portable illuminance meter; fasting blood sample for high-sensitivity C-reactive protein (hs-CRP) assay was collected. At 3-year follow-up, 20 healthy young adults (10 LANavg < 5 lx, 10 LANavg ≥ 5 lx) were recruited from the same cohort; time-series venous blood samples were sampled every 4 h over a 24 h-cycle for the detection of 8 inflammatory markers. Circadian rhythm of inflammatory markers was assessed using cosinor analysis. RESULTS: At baseline, the average age of the 276 participants was 18.7 years, and 33.3 % were male. Higher levels of bedroom LAN exposure were significantly associated with increased hs-CRP levels. The association between bedroom LAN exposure and systemic inflammation was only significant in the inactive group (MVPA < 2 h/d) but not in the physically active group (MVPA ≥ 2 h/d). In addition, exposure to higher levels of nighttime light (LANavg ≥ 5 lx) disrupted circadian rhythms (including rhythmic expression, circadian amplitude and circadian phase) of some inflammatory cytokines and inflammatory balance indicators. CONCLUSION: Exposure to bedroom nighttime light increases systemic inflammation and disrupts circadian rhythm of inflammatory markers. Keep bedroom darkness at night may represent important strategies for the prevention of chronic inflammation. Additionally, for people living a community with higher nighttime light pollution, regular physical activity may be a viable option to counteract the negative impacts of LAN exposure on chronic inflammation.

Ambient light intensity affecting ultrasound operator detection of liver lesions in cine-clips.

INTRODUCTION: Ambient light (AL) is an important factor to improve ultrasound pathology detection. However, there are no established room AL levels recommended during an ultrasound examination. We aim to examine the diagnostic accuracy using different intensity of AL for the detection of liver lesions in anonymised pre-recorded cine-clips. METHODS: Eight ultrasound operators with 5-14 years' professional experiences were prospectively recruited to evaluate 51 randomised cine-clips directly from one ultrasound machine. These 15-s clips of the right lobe of the liver in longitudinal and transverse planes were meant to simulate the ultrasound examination. Operators reviewed all cine-clips and responded to two questions per cine-clip regarding their detection performance under 3 AL settings; 3, 15 and 25 lux, at one lighting per visit. A repeat visit under each AL was performed to assess for intra-operator variability. Each operator completed six visits in total, with at least a 2-day washout period. The operators' performance was compared against imaging reference standards from contrast CT/MRI for cine-clips with lesion and serial US for those without. RESULTS: AL with highest degree of diagnostic accuracy was found to be at 25 lux. Results from 8 operators revealed sensitivity ranged from 79% to 100%, specificity ranged from 94% to 100%. Positive and negative predictive values were up to 100% with AL at 25 lux. Both intra-and interrater reliability were excellent at 0.85-1.0 (0.79-0.98) and 0.98 (0.97, 0.99) respectively, with AL at 25 lux. CONCLUSION: This study proved that ambient light intensity affects the ultrasound operator detection of liver lesions on cine-clips. IMPLICATIONS FOR PRACTICE: Identifying suitable AL levels will influence future ultrasound room construct.