Our lights and eyes

Concerns that LEDs may be harmful to vision are not new. Experts suspected that this might be because, to achieve their white light, photodiodes use so-called blue light as a base, which "moves" in the short wavelengths of the visible light spectrum (380-500 nm) and has high energy. Some experiments on rodents and monkeys have suggested that exposure to blue light, especially at wavelengths of 400-500 nm, causes damage to the retina. The corresponding experiments on humans (which in this case are done on cells) are really few and have been carried out either with natural light or with other types of lamps. The first study to examine the effect of LEDs on human retinal cells was just recently published in the journal "Photochemistry and Photobiology," and its results appear to confirm scientists' fears.

Researchers from the Complutense University of Madrid who conducted it found that these lamps, which are increasingly used to illuminate not only our homes and offices but also our mobile phone, television, tablet and computer screens, may cause irreparable damage to vision by reducing the lifespan of photoreceptors, the precious light-sensitive cells in our eyes. The scientists exposed cells from the human retinal pigment epithelium to various types of LEDs (red, green, blue and white light) during twelve-hour light/dark cycles. They saw that after three light/dark cycles, the blue, green, and white light from LEDs drastically reduced the viability of photoreceptors (by 99%, 88%, and 75%, respectively), often leading them to apoptosis, the natural death of cells.

"This is very important because the retina, the inner layer of our eye, is made up of tissues of the central nervous system - that is, they are tissues that do not renew, their cells are postmitotic and cannot be renewed," explains Thelia Sanchez-Ramos, professor of Optometry at the Complutense University and one of the leaders of the study, speaking to "Vima".

The most serious thing is that, as the results suggest, the harmful effects of LEDs are not limited to the moments when we look directly at the screen of our computer, television or mobile phone – which are already many – or to those when we read our book under a lamp. They also continue to exist when we are simply in a space that is illuminated by them. “In space, of course, we do not look at the source of light, but it still causes damage, and a lot of it. It causes damage if it has a lot of energy, the problem is the energy,” the professor points out, adding: “Perhaps not all LEDs emit blue light in a quantity that is harmful, but many probably do.

The Spanish researchers emphasize that further studies are needed to determine the harmful and safe "doses" of radiation that human eyes can receive so that effective safety regulations can be established. However, the "bell" has already been sounded, since mobile phone, television and computer screens keep our eyes fixed on them for more and more hours, already from a very young age. Also, a main source of concern for many experts is the fact that, based on European - and not only - legislation, new technology bulbs will completely replace conventional incandescent bulbs in the coming years. However, both of their widespread types - LED and CFL - appear to be problematic for human health in one way or another. The need to find a solution is therefore urgent.

Researchers at the University of Madrid have presented an idea that, although simple, has proven effective in the eleven-year clinical trials they conducted to “test” it (it has even been shown in studies to “slow down” macular degeneration). They have developed special filters for eyeglasses that protect against harmful light radiation and which were released just last week in Spain. This is a treatment similar to those that make, for example, the lenses of glasses less “visible” or offer more relaxing computer use. “They have a slightly yellow color – golden, my colleagues here tell me – and are almost invisible if someone doesn’t know it,” says Dr. Sánchez-Ramos, who has won many international awards for the development of therapeutic lenses and treatments. "Our goal was for anyone to be able to use them, whether they are nearsighted or farsighted, or have astigmatism or hyperopia. But we were mainly interested in them being able to be used by young people, because young people are the ones who will be exposed to LED lighting for the longest time.

Our eyes, explains the professor, have natural filters that protect them from the harmful “parts” of light radiation, and the filters she and her collaborators developed work in the same way, blocking harmful blue radiation and preventing it from reaching the retina. “It’s very simple: we imitated nature, we copied the natural filters that the macula of the eye has, that is, we artificially reproduced its own pigments and put them in the lenses of the glasses,” she says. “Thus, these filters “collaborate” with the retina and slow down its aging, extending its lifespan.

The next step is even more “drastic”, since it concerns the application of these filters to the LED bulbs themselves. “They will be applied as a coating on the outside of the bulb and will provide the same protection,” explains the professor. “They have not yet been released on the market, but we already have agreements with major manufacturers and I believe they will not be long in coming.” If, while waiting, the idea of ​​an improvised temporary protection by covering the LED bulbs you have at home with a yellow, for example, windshield comes to you, do not try it. As Ms. Sanchez Ramos tells us, this will possibly change the amount of blue light, but at levels that you are not able to measure to know if you are actually protected, while it certainly will not absorb harmful radiation like special filters. In addition, it will change the quality of the light, tiring your eyes more.

Is there any provision for the development of special filters for mobile phone or computer screens? “We are working hard on that,” the expert replies. “That’s all I can tell you at the moment.

THE “KING” OF BLUE LIGHT
Advantages and pitfalls of LEDs
Light-emitting diodes work completely differently from other lamps since they are an electromagnetic source of lighting – in essence, they are semiconductors that emit light radiation when they receive electrical voltage. They have much greater efficiency than conventional lamps – and therefore offer huge energy savings -, as well as a much longer lifespan (35,000-50,000 hours when an incandescent lamp lasts 1,000-2,000 hours and a fluorescent lamp 10,000-15,000 hours). They offer light of various colors while emitting minimal heat, but their white does not resemble sunlight so much (something that incandescent lamps achieve).

Although they are more expensive, their high efficiency and long life more than compensate for this, while they do not contain toxic ingredients. That is why they have been unanimously declared the most environmentally friendly lighting source. All of the above advantages, combined with their small size and flexibility, have skyrocketed the use of LEDs not only in the screens of electronic devices but also in the lighting of outdoor and indoor spaces (Philips, for example, announced last April that its LED sales increased by 38% in 2012).

With the expansion of use, however, the unpleasant aspects are slowly coming to the surface as researchers begin to examine their effects. In 2010, the British public health authority Anses recommended that parents take care to keep their children away from spaces lit by LEDs and to avoid toys with light-emitting diodes because their bright light appears to cause “toxic stress” to the retina. This year, in addition to the study by Spanish scientists, a more “artistic” study published by an international team of researchers in the Journal of Analytical Chemistry and causing strong reactions found that the wavelengths of light emitted by some LEDs destroy the paint in Van Gogh’s works – specifically, they cause the painter’s characteristic yellow color to take on brownish hues. It is noted that LEDs were initially considered friendlier to works of art as they do not raise the temperature, which is their known "enemy". However, beyond the alteration of the colors themselves in the paintings, many experts point out that the white light emitted by LEDs and new technology lamps alters the perception of colors by the human eye.

BLUE LIGHT, PULSE, INFRARED
Fluorescent and halogen lamps
In addition to LEDs, the most common lamps today are compact fluorescent lamps or CFLs – also known simply as “energy saving lamps” – and halogen lamps. But here too, problems seem to arise.

CFLs, which are fluorescent lamps in a tubular, spiral or spherical shape, have been blamed primarily for the mercury they contain. This reason for concern, although serious, is mainly environmental – which is why these lamps must be destroyed in a special way and therefore not thrown into the "common" waste bins, and if they break they require careful handling. However, our eyesight is not directly threatened by this cause.

"Mercury causes damage to the body when it is inside the body, but not when  light produced by lamps containing mercury "falls" into our eyes," explains Tatiana Skoutari, a professor at the Complutense University, who now works as a specialist optometrist in Athens, speaking to "Vima". "The problem with this technology, which is also used in LCD and TFT screens, is that it emits blue light and therefore may cause damage to the retina and promote or accelerate macular degeneration and other degenerative diseases such as diabetic retinopathy, Stargardt's disease or retinitis pigmentosa."

Also last June, a study by researchers at Stony Brook University in New York, conducted on human skin cells and published in the journal “Photochemistry and Photobiology,” accused CFLs of increasing the risk of skin cancer due to the ultraviolet radiation they emit. The researchers recommended the use of “double” glass in the lamps for greater protection, but their findings provoked a reaction from the manufacturers of these lamps, who issued a statement claiming that the UV radiation emitted by CFLs is at safe levels.

Ms. Skoutari, for her part, points out another problem with CFLs and fluorescent lamps in general: the fact that they do not emit continuous light but pulsed light (known as “flickering”). “This,” she explains , “is not perceived by the human eye, but is perceived by the brain, resulting in frequent headaches, migraines, drowsiness and a decrease in the ability to concentrate.” Finally, she adds, this type of radiation has been accused of affecting the body’s melatonin levels, causing disruptions to our biological clock. “Studies have linked melatonin levels to the risk of depression and even cancer,” she concludes.

Halogen lamps, which contain the inert gas halogen and iodine and bromine vapors, are essentially incandescent lamps and offer continuous light. “Traditional” incandescent lamps, although they are being phased out as environmentally unfriendly, are ultimately proving to be the friendliest for our health because they offer the closest thing to natural light so far. In the case of “enhanced” halogen lamps, however, there are some risks due to the ultraviolet radiation they may emit. “They should have special filters in their housing because otherwise they emit significant amounts of UVA and UVB, and even UVC,” says Mrs. Skoutari. “Ultraviolet radiation can cause photokeratitis, clouding of the cornea, as well as accelerated hardening of the lens, which is what we commonly call “cataracts”.”

All of this sounds rather alarming, but the hopeful thing is that both scientists and manufacturers are working hard not only to improve the quality of light from the “new”, now mandatory bulbs, but also to identify and correct any adverse effects they may have. In the meantime, what can we do to protect ourselves? “Since we cannot return to incandescent bulbs, it is good to at least adopt some good habits,” the optometrist answers. “Always wear glasses with special filters on the computer or tablet, stand at a safe distance – about 70 centimeters from the screen – and be careful that lights from the environment are not reflected on the screen. Also, make sure that halogen bulbs have special filters to protect against ultraviolet radiation and do not read directly under the light of the bulb because we receive more radiation as the light is reflected on the pages of the book. It is better to prefer hidden lighting, because this way the radiation is diffused and does not come directly into our eyes.