Part
01
of nine
Part
01
Light Spectrum Effects on the Body
Visible light spectrum can cause aging in skin cells physiologically, and cause damage in the retinal neuron, especially the blue visible light.
PHYSIOLOGICAL EFFECTS: LIGHT EFFECTS ON SKIN CELLS CAN CAUSE PREMATURE AGING
PROPOSED MECHANISMS TO GET THE LIGHT INTO THE BODY
- The skin cells are attached to the electrode then put the resistance of cell in 10-15 hours to reach a steady state as the same condition as skin cell in the human body.
- After reaching the cell confluence, the lights were exposed to an on/off series with gradually increasing time intervals of 1 to 2.5 hours.
- The lights are made of 8 LED with different RGB colors as visible light spectrum equipped with its control setup, thermocouples, eight well ten electrodes (8W10E) ECIS culture chip, thermocouples, and PC (data-acquisition system) with a software interface.
MAGNITUDE
- The visible light spectrum has blue-460 nm, green-530 nm, red-625 nm, and white light radiation.
- Cells were exposed to intermittent, mild, and intense radiation with the timing from 1 to 180 minutes light with on/off cycles, using blue, green, red, and white light.
CERTAINTY OR CONFIDENCE
- How certain are the scientists with this work: The scientists were certain with this work to the extent that this research advanced the understanding of the different color light-induced degenerative process.
- The study can help in the development of new therapeutic strategies.
TYPES OF EFFECT OBSERVED
- Visible light can cause premature aging on the skin cells.
OUTCOME METRICS VS QUALITY OF EVIDENCE
- Outcome metrics using LED glare to human cells: Blue light exposure shows a significant decrease in cell viability at 150 minutes. The research found that about 12% of the cells died after 150 minutes of exposure.
- Quality of evidence: Another study stated that the uses of LED lighting as a visible light spectrum to the human body is promising because it has the same effect and it can cause physiological damage directly and lead to various health problems. It also stated that blue light may also contribute to skin aging similar to UVA.
DOSE-RESPONSE RELATIONSHIP
- More time exposure of visible light spectrum to skin cells is equivalent to more dead skin appearance.
TYPE OF APPLICATIONS
- Type of application on the human body: skin cells
NEURAL EFFECT: VISIBLE LIGHT SPECTRUM, ESPECIALLY BLUE LIGHT, CAN DAMAGE RETINA NEURON CELL
PROPOSED MECHANISM TO GET THE LIGHT INTO THE BODY
- In this study, the researcher used rat retinal cells, those were isolated from four eyes of one-day-old rats for each experiment. The retina cells were isolated then incubated for 20 minutes in a media with trypsin to dissociate the cells.
- The retinal cells were maintained in the dark or exposed to white light (900 lux, 1500 lux), or blue light (900 lux, 1500 lux) for about 2 hours then transferred to a dark incubator for incubation, the cells were taken at 2h, 24h, and 48h.
- The short term blue light is achieved by an LED system in a cellular incubator where the cells were maintained under culture conditions. This LED cellular system produces a low radiant heat output, avoiding hyperthermic disturbance.
MAGNITUDE
- Blue light (450–495 nm) with the radiation of 900 lux impairs cell viability and induces cell apoptosis in retinal neurocytes in vitro.
CERTAINTY OR CONFIDENCE
- How certain is the scientist with this work: Based on the findings, the researchers are convinced and certain with their work and declared no conflict of interest.
- The researchers were sure that their study provides new insights into the mechanisms of the effect of blue light on the retina.
TYPES OF EFFECT OBSERVED
- Visible light spectrum, especially blue light, can cause retinal damage.
OUTCOME METRICS VS QUALITY OF EVIDENCE
- Outcome metrics: Blue light-induced changes in the integrity of retina thickness that when the retina is exposed to blue light, the thickness is 227.1 ± 9.7, * p < 0.001. While when in the control visible light spectrum, the thickness is 266.5 ± 6.38. The thickness is different and it was stated that blue light exposure can induce severe retinal damage.
- Positive cells damaged in white visible light spectrum is only 2% while on the blue light is 35.3%. This finding shows that DNA assay shows severe DNA damage in the retinal neuron at 2 hours after blue light treatment.
- Quality evidence: A study with the title "Does rat retina make relevant model for discussing exposure limit values applicable to humans?", answered that there's no clear consensus of rat model and undermines the validity of exposure calculations, unless the values can be justified by biological measurement.
- But a study with living human cell justified that blue visible light spectrum distorts plasma membrane on retina phospholipid, phosphatidylinositol 4,5 bisphosphate (PIP2), and disrupt its function.
- Another evidence shows that visible light spectrum makes a large number of mitochondria in retinal ganglion cells when exposed to visual light of 400–850 nm and the blue lights negatively affects mitochondrial function causing stress and decreased cell survival.
DOSE-RESPONSE RELATIONSHIP
- More blue light is equivalent to more damage on retina cell.
TYPE OF APPLICATIONS
- Type of application on the human body: eyes