Abstract
Modern times have made all sections of human society immensely reliant on digital technology and devices. These technological advancements in the form of computers, TVs, mobile phones and other digital electronics have become a vital part of life and contribute towards a major portion of daily routine. All these activities have one thing in common: screen time. This screen time is the one most basic source of blue light exposure. However, it is ever present all across the universe. It is basically a color in the visible light spectrum that is visible to the human eyes. It has a short wavelength; hence it produces higher amounts of energy. Researchers show that continued exposure to blue light can be extremely harmful to human health. It can become a major cause eye strain, fatigue, continued headaches and sleeplessness among children and adults. Moreover, it potentially damages the retina, causes cataract and disturbs hormonal balance of the brain. As people have become more and more aware of the effects of light pollution to the human eye, blue light has been identified as a growing future concern with continued research in prevention and treatment ongoing.
Introduction
Light wavelength of between 300 and 400 nm has the potential to penetrate the cornea of the human eye and be absorbed by the iris or pupil. Direct penetration of blue light crystals to the retina potentially causes irreversible photochemical retinal damage (Bi, et.al, 2014). From a basic level of eye discomfort, blue light of short wavelength can cause worsening of visual fatigue, nearsightedness and mental effects such as diplopia (Zhao, et.al, 2018). This report attempts to examine various proportions of blue light exposure and its effects on human eye in specific and other harmful symptoms in children and adults.
The visible spectrum of the sun constitutes of 50% of the light spectrum and of it, blue light is the only detectable light by the human eye. Apart from its presence in the environment, it has been brought into homes with various digital electronic devices. This increased exposure to blue light at close proximities has many health hazards among both children and adults. This is because the human eye is not ideally designed to block and deflect blue light. It absorbs it in the retina where photoreceptors transform it into an electrochemical signal (American Optometric Association). This absorption contributes to a thermal stress on the retina, where certain photoreceptors become oxidative. Increased exposure to blue light has also been found as cause of photoreceptor death in research on rodent and primate models. Hence, exposure to blue light for increase durations under light given by digital electronics or even natural sunlight can be fatally harmful in many underlined ways.
Exposure to blue light
Continuous exposure to blue light, especially at night time has been linked as a possible cause of diabetes leading to cancer. In a research conducted at Harvard University, the researchers put 10 people on a schedule that gradually shifted the timing of their circadian rhythms (Harvard Health Publishing, 2012). Blood sugar levels in these research participants were observed to increase which led to initialization of a pre diabetic stage. The research also observed that their levels of leptin hormone dropped, which is usually the case after having a full meal.
Even very little light can trigger a person’s circadian rhythms and melatonin secretion. According to a Harvard sleep researcher Stephen Lockey, as low as eight lux of light brightness can have an effect. Such a level of brightness is common to most table lamps. This phenomenon is most devastative at night time and according to Lockey, it is why many people don’t get enough sleep. Nowadays, mobile phone usage at night is a common instance and it only increases the likelihood of detrimental effects caused by blue light. Harvard researchers in another experiment compared 6.5 hours of exposure to blue light to exposure of green light of comparable brightness for the same duration. It was observed that blue light suppressed the creation of melatonin hormone while also shifting circadian rhythms twice as much as green light participants. The melatonin glands are produced at the center of the brain and are responsible for organizing sleep cycles in the human body. Researchers have linked irregular night routines to increased risk of depression, diabetes and other cardiovascular problems (Harvard Health Publishing, 2012). In another study, researchers at University of Toronto confirmed the role of blue light in suppressing melatonin levels. They compared the secretional levels in people exposed to bright indoor light while wearing blue light blocking goggles to those exposed to regular dim light without wearing goggles. The melatonin levels in both groups were relatively observed to be the same.
While research affirms that blue light is suppressor of melatonin, it also suggests that night shift workers and those exposed to excessive light during night times can wear eyewear to block blue light. Other suggested methods to avoid blue light exposure is to use dim red lights at night, avoiding looking at bright screens for prolonged durations before going to bed and getting increased exposure to bright light during the day so to boos sleep ability at night.
Blue Light and Children
Exposure to blue light has a higher risk od retinal damage in children than adults. This is because the lesser mature eye lens absorbs lesser light of short wavelength than a mature lens. This takes light straight through to the retina and becomes a potential cause of development of cataract, eyelid cancer, pterygium and soft drusen in children (Zhao, et.al, 2018). In case of electronic digital devices, the light is not on its own strong enough to damage the human retina but is able to stimulate blue light sensitive cells/photoreceptors to irregulate circadian rhythms. Usage of these devices such as tablets, phones, laptop, etc. before bedtime is highly discouraged for children as is causes symptoms of dry eyes, blurred vision and headaches. To counteract, amber tinted spectacle lenses can be used to reduce the altering effects of blue light (McCarty, et.al, 2001).
Further mentioned are the harmful effects of blue light causing harm to specific human senses and organs.
Eyestrain
The digital devices, especially computer and mobile screens emit significant blue light and greater exposure to these devices render great harm to the human eye. The blue light waves carrying high energy and low wavelengths scatter when they enter the eye and blurs vision. This scattering phenomenon creates a visual noise in the eye that reduces contract of viewing and contribute to digital eye strain (Canadian Association of Optometrists). A term known as digital eyestrain has been identified by opticians relating to serious symptoms caused by exposure to digital blue light. Symptoms of digital eyestrain include blurry vision, bad focus, dry and irritated eyes, headaches, neck and back pain. According to research conducted by Blue Light Exposed, digital eyestrain has overtaken carpal tunnel syndrome as the number one computer-related complain. The risk potential for digital eyestrain is greater among children than adults as they are more equipped with digital tools like smartphones and tablets at their disposal. According to a study by the Kaiser Family Foundation, children and teenagers within ages 8-18 spend in excess of 7 hours consuming digital media. The crystalline lens and cornea within individuals of this age group is not entirely developed and is largely transparent and overexposed to blue light.
Retinal damage
Retina is where the initial vision formation in the eye takes place. It is the hub of many blinding diseases while also the prevention center for many anomalies. Blue light possessed the potential to penetrate through lens to reach the retina and cause retinal photochemical damage.
The oxidative effects of stress caused by blue light has been studied on rabbit retinas which showed that the retina after 24 hours of blue light irradiation had become disordered in the inner and outer segments of the photoreceptor cells. The outer retinal nuclei were scattered and the photoreceptor cells mildly disordered (Nakamura, et.al, 2017). The International Journal of Ophthalmology (2018) states that under aerobic conditions, blue light stimulates the mechanism of retinal initiation and oxidation while destroying messenger ribonucleic acid (mRNA) and proteins. It causes necrosis of the photoreceptor cells and destroys the dynamic balance of the body’s normal state.
Increased exposure to blue light can damage the sensitive retinal cells which could lead to permanent loss of vision. This cumulative effect of blue light exposure affects the photo sensitive cells responsible for central and color vision in retinal pigment epithelium. Essentially the cells responsible to nourishing retinal cells. Against these hazards, Lutein, a blue blocking pigment is present in stable and healthy retinas which is found to protect against blue light photo damage.
Cataract
Cataract is one of the most identifiable causes of blindness worldwide. It is the damage of eye lens which is the most crucial system in the human eye. It contains structural proteins, enzymes and metabolites to absorb and filter short wavelengths of waves. As blue light enters the lens in increased quantities, it is added to the lens’ protein to produce yellow pigments. This gradually darkens the lens and turns it yellow. However, to protect the retina from blue light exposure, the lens increases blue light absorption and undergoes decrement in transparency which results in cataract formation. According to the Canadian Association of Optometrists, by the age of 20, the lens has yellowed enough to filter very little blue light. This contributes as a factor to aging of the lens and retina along with cataract formation.
Macular Degeneration
Blue light exposure has been associated with drastic harms such as permanent eye damage, destruction of retinal cells. It is also found to be contributive towards age-related macular degeneration, which can potentially lead to vision loss. Macular degeneration is caused by lacking levels of Melanin in the substance of the skin, hair and eyes that absorb harmful UV and blue light rays. Macular degeneration can also be associated with aging, but exposure of retina to high radiation waves that penetrate the macular pigment also contribute towards its lacking. A paper published by the American Macular Degeneration Foundation (AMDF) reports that blue rays of spectrum accelerate age related macular degeneration more than any other rays in the spectrum.
Summarizing, a certain exposure to blue light directly from the sun and increased outdoor activity, usage of mobile, tablets and laptops during night and general degraded sleeping patterns can hugely contribute to many diseases that can even prove to be fatal. Starting from simple headaches, sleeping disorders and eyestrains, blue light exposure can lead to irregular circadian rhythm, disorder in brain hormones, along with damaging effects to the cornea, lens and retina in the human eye. Therefore, it is necessary to control blue light exposure and lessening digital electronics usage while also using protective measures during periods of blue light exposure.
References
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Harvard Health Publishing, 2012. Blue light has a dark side. Harvard Health Letter, Harvard Medical School.
American Optometric Association. Blue Light Impact in Children. Infant & Children’s Vision.
McCarty CA, Mukesh BN, Fu CL, Mitchell P, Wang JJ, Taylor HR. Risk factors for age-related maculopathy: The Visual Impairment Project. Arch Ophthalmol 2001; 119:1455-62.
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Zhao, C.Z., Zhou, Y., Tan, G., & Li, J. 2018. Research progress about the effect and prevention of blue light on eyes. International Journal of Opthalmology. 11(12), 1999-2003.