The effects of blue light on eyes

Ari Rednour. 8/16/2020

Technology surrounds our daily lives, quite literally. Especially as much of the globe has gone into quarantine since COVID-19, the use of technology has significantly increased, as people have turned to electronics to finish the curriculum of the school year, connect with friends and family, and entertain themselves to pass the time. Before the pandemic, research proved that the blue light emitted from the screens of technological devices negatively impacts the health of one’s eyes. But especially in times like these of increased exposure to the screens of cell phones, computers, and televisions, the amount of daily blue light one consumes only further detriments one’s health.

The visible light spectrum is a part of the electromagnetic spectrum visible to the human eye. The wavelengths covered by the visible light spectrum range from 380nm (blue-violet) to 700 nm (red). Blue light, also known as high-energy visible (HEV) light, entails wavelengths of approximately 380nm-500nm, which is about one-third of the visible light spectrum. Noting the inverse relationship of wavelength to energy, the short wavelengths of blue light means it has higher energy in relation to the other colors, such as red.

A major source of blue light is the sun. The sun emits white light, which is a combination of all of the colors of the visible light spectrum. Why is the sky blue? That is a commonly asked question, especially amongst young students in grade school. The short wavelength and high frequency of the HEV rays scatter more easily against air and water molecules than any other visible light and therefore paints the sky blue.

Not all blue light is bad. Blue light is pretty environmentally friendly. During the day, blue light helps to increase one’s attention, mood, and reaction time. The sun is a major source of blue light; however, the majority of one’s blue light intake comes from the screens of electronic devices and man-made fluorescent and LED lighting. While electronic devices emit these HEV rays at a fraction of what the sun emits, the amount of time people spend in front of these devices in such proximity raises concerns, especially in the medical community.

Through studies, blue light has been proven to disrupt one’s ability to sleep and cause eye strain. Blue light suppresses the production of melatonin, which is the hormone that regulates one’s circadian rhythm, or internal clock of when to sleep and wake up throughout the day. A Harvard research experiment tested the participants’ circadian rhythms by comparing the effects of six and a half hours of exposure to blue light and green light. The results found that the blue light suppressed the melatonin levels of participants for twice as long as the green light, and therefore shifted circadian rhythms by twice as much (i.e. one and a half hours compared to three hours). Not only do HEV rays interfere with one’s sleep schedule, but they also trigger eye strain. First, staring at anything for long periods causes eye strain because of increased focus and less blinking. As mentioned previously, blue light scatters most easily of any visible light which causes it to be “less focused.” The “unfocused visual noise” decreases the contrast of an electronic device and contributes to digital eye strain, as the eye tries to intake and differentiate what is on the screen.

In 2018, major research conducted at the University of Toledo explored the effects of blue light on the eye. Ultimately, when blue light hits a retinal molecule, this creates reactions that are toxic to the cells in the retina, which is the part of the eye that takes in light and converts it into neural signals so the brain can recognize its visual surroundings. In the retina, there are photoreceptor cells, called rods and cones, that detect light. Rods make up the majority of these photoreceptor cells, and they rely on proteins called rhodopsin to detect light. Retinal (C₂₀H₂₈O), which is connected to the opsin protein and makes up a part of the rhodopsin, is an oxidized version of retinol (C₂₀H₃₀O), also known as Vitamin A. When photons hit the retinal molecules, it undergoes isomerization and changes the shape of the rhodopsin slightly. With limited space around the retinal, this shifts the rhodopsin out of the way, which sets off a series of chemical reactions. These chemical reactions are converted to signals, which are sent along the optical nerve to the brain.

Associate professor of the Department of Chemistry and Biochemistry at the University of Toledo Ajith Karunarathne, Ph.D., works at the university’s cellular photochemistry laboratory and led this experiment. He experimented with retinal against immortal HeLa cells, as these cells continuously divide into more versions of themselves. The HeLa cells were an experimental substitute for photoreceptor cells, and when exposed to blue light with the retinal, this triggered the distortion of an important protein in the cell membrane and increased the oxidative damage and calcium levels in the cell. However, blue light alone on these cells, retinal with these cells without the blue light, and/or retinal with these cells with a different color light did not kill them. Kasun Ratnayake, a Ph.D. involved in the study, stated, “It’s toxic, if you shine blue light on retinal, the retinal kills photoreceptor cells as signaling molecule on the membrane dissolves.” He also stated that “photoreceptor cells do not regenerate in the eye . . . When they’re dead, they’re dead for good.”

Karunarathne posed another question though. If the blue light on retinal is so deadly to the cells that help one see, why does one’s vision not degrade more rapidly? He discovered that with the presence of alpha-Tocopherol (C₂₉H₅₀O₂), a type of vitamin E and antioxidant, the damage caused by blue light and retinal is decreased and prevents cell death. Although, as one ages, vitamin E decreases in the body and one loses this protection against blue light. Karunarathne proposed that over time, the continuous destruction of these light-detecting cells from prolonged exposure to blue light contributes to age-related macular degeneration (AMD), which is the leading cause of blindness with more than two million new cases in the United States per year. He wishes that his research and further discoveries will help to develop a way (i.e. eye drops) to intercept the toxic reactions occurring between the retinal and blue light in the eye. He states that he “hopes to find a way to protect the vision of children growing up in a high-tech world.”

While these new discoveries were a breakthrough in this area of expertise, uncertainty remains. Dr. Sunir Garg is a clinical spokesperson for the American Academy of Ophthalmology (AAO) and has his respectable doubts about the relation of the findings in the research to AMD. He states that the current study “does not show if the intensity and duration of blue light exposed by digital devices cause AMD.” Ultimately, more research needs to be done to determine all the causes and factors that lead to AMD, but this experiment opened the doors to further study of the effects of blue light on the eye.

It is just about impossible to eliminate blue light from entering one’s eyes, but there are ways to decrease the amount one intakes and try to improve one’s health. Normal glasses and sunglasses have been developed with blue light filtering lenses, whether one has a prescription or not. These glasses shield the majority of blue light emitted from electronic devices, which helps to prevent the toxic chemical reactions between the blue light and retinal in the eye. Additionally, to try to maintain circadian rhythms, it is advised to not look at electronic screens in the dark and to not look at screens two to three hours before sleeping at night. Finally, exposure to bright lights during the day, such as going outside where the sun is, boosts one’s mood and alertness during the day, as well as one’s ability to sleep at night.

With the rapid development of new technologies, it proves commendable that one can have access to so much information at the tips of one’s fingers. However, with the new advancements in technology, especially with devices with screens that emit blue light, it is important to know the harms they may cause as well. Moreover, during the current times of this pandemic, society is spending much more time indoors, surrounded by blue light. The LEDs that illuminate one’s home, the computers used for work and school, and the cell phones for daily life create a bubble of blue light much of the population lives in. So it is in one’s best interest to try to limit time with electronics and enjoy the natural blue light outside during the day.

Cover Photo: (Sleep Review)