ABSTRACT
Abstract The aim of this study is to investigate the effect of a continuous stream of pulses of monochromatic blue pulsed (BP) and a combination of blue and green pulsed (BGP) light-emitting diode (LED) light conditions on physiological responses. This study is an approach to clarify the most suitable LED combination and flickering frequency to evoke alertness when a continuous stream of pulsed LED light is delivered and may suggest applications of continuous pulsed light as support for task illumination for shift workers, hospital nurses, school students or office employees. Combinations were delivered by exposures of BPLED and BGPLED pulses at 100, 200, and 400 Hertz over two background light colors (BLC). Participants were exposed to 12 different light conditions in a counterbalanced procedure. By integrating measures of electroencephalogram (EEG) and pupil constriction; results suggested significant changes in responses during the interaction of BLC, LED, and EEG. Beta waves exhibited a statistically significance (p < 0.05) in arousal levels when exposed to BG light, although no active task was involved during exposure. Furthermore, pupil reacted with larger constriction towards BGPLED exposure than towards monochromatic BPLED exposure, thus demonstrating that a continuous stream of pulses can deliver the same irradiance as if delivered in a continuous flow and without affecting perception as no flickering was perceived in any of the conditions by a qualitative evaluation.
Resumen Este estudio tiene por objetivo determinar cuál es la combinación de luz LED más adecuada y la frecuencia de parpadeo que esta deba tener, para evocar un estado de alerta cuando se emite un flujo continuo de la misma al combinarla con una iluminación de ambiente; y poder sugerir aplicaciones como soporte para la iluminación de tareas para trabajadores por turnos, enfermeras, médicos, estudiantes; o en oficinas y hospitales. Es de original importancia resaltar que en el mercado no existe un producto comercial que se pueda ajustar para apoyar en el trabajo al estado de alerta, se tiene la limitante que estas son pruebas a nivel laboratorio y que posteriores pruebas serán necesarias para validar el producto final. El método usado se basó en las combinaciones que se administraron mediante exposiciones de luz azul pulsada (BPLED) y luz azul y verde combinadas (BGPLED) a frecuencias de 100, 200 y 400 Hz adicionadas a la iluminación ambiental (BLC). Los participantes fueron expuestos a 12 condiciones de luz diferentes en un experimento balanceado y contrapesado. Mediante la integración de medidas electroencefalográficas (EEG) y de constricción pupilar; los resultados sugirieron cambios significativos en las respuestas durante la interacción de BLC, LED y EEG. Las ondas beta mostraron una significancia estadística (p <0.05) en los niveles de activación cuando se expusieron a la luz BGPLED, además, la pupila reaccionó con una mayor constricción hacia la exposición a BGPLED que hacia la exposición BPLED monocromática, adicionalmente se demostró que un flujo continuo de pulsos puede proporcionar una irradiación igual a la que se emite en flujo continuo; se concluyó e identificó además la frecuencia (100 Hz) que mejor evoca estado de alerta encefalográfíca y sin afectar la percepción de los usuarios en cuanto a su percepción del ambiente de acuerdo a la evaluación cualitativa.
ABSTRACT
Abstract Purpose: An experiment was conducted to investigate the physiological effects of a continuous blue pulsed light emitting diode (BP-LED) added to a task lamp in an actual indoor lighting environment and its influence in alertness having as a final purpose to develop a commercial product that could be applied in situations similar to those depicted in the present work. Design methodology: Previous research studies have stated that the addition of pulsed light evokes physiological changes that may induce alertness. The participants were exposed to four different lighting conditions. Electroencephalograms (EEG), pupil sizes, heart rates (HR), performance tests, and subjective reactions were measured. Findings: Low colour temperature light and the BP-LED revealed an improved alertness according to the data from the EEG recordings. The intervention of the BP-LED in a high colour temperature ambiance was beneficial in maintaining high levels of alertness compared to the conditions where the BP-LED was not used. It was tested that the use of a BP-LED in a task lamp may be beneficial in improving or maintaining alertness levels in an indoor workplace ambiance. Originality and Value: Designing of an adequate workplace task lamp light that improves alertness for in-house, office, or classroom situations in which it is essential.
Resumen Propósito: Un experimento fue llevado a cabo para investigar los efectos fisiológicos que una luz azul LED pulsada de manera intermitente (BP-LED), adicionada a una lámpara de escritorio, y en un ambiente interior; pueda influir en el estado de alerta de una persona con la finalidad de desarrollar un producto comercial que pueda ser aplicado para los casos desarrollados y otros posibles escenarios. Metodología de Diseño: En estudios anteriores se establece que la adición de luz en pulsaciones evoca cambios fisiológicos que pueden inducir al estado de alerta. Los participantes experimentaron cuatro escenarios de iluminación. Se registraron mediciones con respecto a encefalografía (EEG), tamaño pupilar, ritmo cardiaco, prueba de performance, así como evaluación subjetiva. Hallazgos: Los datos de EEG revelaron un mayor estado de alerta durante la exposición a iluminación cálida aunado a luz BP-LED. La intervención de luz fría y BP-LED denotó ser benéfica en el nivel de estado de alerta en comparación con las condiciones donde el BP-LED no intervino. Se logró evaluar que el uso de BP-LED en una lámpara de escritorio puede ser benéfico para mejorar o mantener el estado de alerta cuando sea usado en un espacio interior. Originalidad y Valor: Propuesta para diseñar una luminaria de escritorio; para uso casero, laboral o de estudio; que mejore el estado de alerta de las personas.
ABSTRACT
Objective To observe the dopamine(DA)concentrations in the lateral geniculate nucleus in guinea pigs with flickering light-induced and form deprivation myopia,and to compare and analyze the pathogenetic mechanisms in the centers of vision of these two different myopia models. Methods Twenty-four two-week-old guinea pigs were randomly assigned to three groups(n=8):flickering light-induced myopia(FLM)group, form deprivation myopia(FDM)group and control group. All the groups were fed for 8 weeks. The refraction and axial length(AL)were measured before and af-ter modeling. After eight-week modeling,the contents of dopamine in the left lateral geniculate nucleus were detected by high performance liquid chromatography with electrochemical detection(HPLC-ECD). Results Before modeling,no sig-nificant difference was found in refraction and AL among the three groups. After eight-week modeling,in contrast with the control group,significant differences were found in changes of both refraction(P<0.001)and AL(P<0.05)in the right eyes of FLM and FDM groups,indicating that the two myopic models were successfully established. The result of HPLC-ECD showed that the contents of DA in the left lateral geniculate nucleus in FLM group were significantly higher than the control group(P=0.01),while in the FDM group it was lower than the control group(P=0.021). The average contents of DA were as follows:(37.04 ± 1.18)pg/μL in the control group;(24.27 ± 3.46)pg/μL in the FDM group; and (45.58 ± 1.98)pg/μL in the FLM group. Conclusions The content of DA in the lateral geniculate nucleus is increased in FLM,while decreased in FDM,indicating that the expression of DA in LGN and the mechanisms of formation of these two experimental myopia are different.
ABSTRACT
Objective To observe the changes of S-opsin expression in guinea pigs with flickering light-induced and form-deprived myopia,and to investigate the causes.Methods Thirty-six two-week-old healthy guinea pigs were randomly assigned to three groups:Flickering light-induced myopia group(FLM group,n=13),form-deprived myopia group(FDM group,n=12) and control group(n=11).For the FLM group,the cages were equipped with astroboscope(0.5 Hz),and LEDs were used as the light source.The right eyes of the guinea pigs in FDM group wore translucent goggles which did not interfere with the normal activity of their eyelids.No special treatment was given to the guinea pigs in the normal groups.All measurements were performed prior to and then after 6 weeks of treatment.The first measurement day was recorded as 0 week.Biological parameters,such as the refraction,axial length(AL) and corneal radius of curvature(CRC),were measured and fundus photography is performed before and after 6 weeks of the treatment.The expression of S-opsin was observed and analyzed by immunofluorescence technique and image analysis system.Results Before the treatment,no significant difference was found in three biometric measurements including refraction,AL and CRC between the groups at 0 week(P>0.05).After the treatment for 6 weeks,significant differences were found in changes of both the biometric measurements between the FLM and control groups,and between the FDM and control groups(P0.05).Expression of S-opsin differed in the FLM and FDM groups.For the mean gray values of green channel,compared with the control group respectively,significant differences were found in both the FLM and FDM group(P<0.001).The mean gray value of green channel of the FLM group was higher,however the mean gray value of green channel of the FDM group was lower.Conclusions Both guinea pig models of flickering light-induced and form-deprived myopia can be established successfully.S-opsin is increased in the flickering light-induced myopia model and decreased in the form-deprived myopia model,indicating that the mechanisms of formation of these two experimental myopia models may be different.
ABSTRACT
Background Flickering light is different from the normal light environment.Animal experiment proved that flickering light can induce myopia.But its mechanism remains unclear.Objective This study was to investigate the expression of c-fos gene in retina of myopic C57BL/6J mice induced by flickering light and monocular form deprivation.Methods Ninety clean C57BL/6J mice aged 28-day-old with the similar refraction in both eyes were randomly assigned to five groups.Fifteen mice in the control group were exposed to continuous white light environment.The white flickering light with the frequency of 10,5,2 Hz were used to irradiate the mice respectively in high frequency flickering group (15 mice),moderate frequency flickering group (15 mice) and low frequency flickering group (15 mice),respectively.The right eyes of other 30 mice were monocularly occluded with a semitransparent hemispherical thin plastic shell to establish the form deprivation models and then were exposed to white light environment.The diopter and ocular axial length were measured by murine-specific eccentric infrared photorefraction and A-scan ultrasonography before experiment and two weeks after the treatments.At the end of experiment,the mice were sacrificed by neck dislocation.Mice eyes were enucleated and retinal samples were prepared for the detect of c-fos protein and its mRNA by immunohistochemistry,Western blot and reverse transcription polymerase chain reaction (RT-PCR),respectively.Results Immunohistochemistry showed that the expressing rate ofc-fos protein in retina was (68.000±10.368)％,(51.000±6.519)％,(46.000±6.519)％,(31.000±7.416)％ and (25.000 ± 7.071)％ in the control group,high frequency flickering group,moderate frequency flickering group,low frequency flickering group and form deprivation group respectively 2 weeks after experiment.The expression rates of c-fos protein in retina in different frequencies of flickering light groups and form deprivation group were significantly lower than that in the control group (t =3.104,4.017,6.490,7.661,all P＜0.05),with the lowest rate in the form deprivation group (P＜0.05).The expression of c-fos detected by Western blot assay exhibited that the relative values of c-fos protein in retina (c-fos/GAPDH) was 0.804±0.050,0.687±0.047,0.667±0.036,0.558±0.036 and 0.532 ±0.056,respectively in the control group,high frequency flickering group,moderate frequency flickering group,low frequency flickering group and form deprivation group,illustrating significantly lowing in different frequencies of flickering light groups and form deprivation group compared with control group (t =2.961,3.184,6.971,6.276,all P＜0.05),whereas the c-fos in the low frequency group and form deprivation group,c-fos protein was less expressed in comparison with the higher frequency flicking group (P＜0.05).The expression level of c-fos mRNA (c-fos mRNA/GAPDH mRNA) in retina was 0.820±0.056,0.663±0.061,0.627±0.034,0.521±0.041 and 0.474 ±0.045 in the control group,high frequency flickering group,moderate frequency flickering group,low frequency flickering group and form deprivation group,respectively.These results demonstrated a significant decline in the expression of c-fos mRNA in different frequencies of flickering group and form deprivation group compared with the control group(t=3.262,5.070,7.173,8.305,all P＜0.05),and the inhibition ability of low frequency of flickering group and form deprivation group was much stronger.Conclusions The c-fos gene level in the retina has a negative relationship with the severity of myopia induced by flickering light and form deprivation.