Don’t just stare at the screen and laugh, you need a guide to protecting your eyes from electronic devices!

I often see parents asking what are the better eye protection products. What I want to say is that if you want to protect your eyes, the best way is to stay away from electronic screens as much as possible. However, this question is sometimes a melancholy. In the past, online classes had a great impact on children's eyesight, and parents were miserable. Now we finally don't have to take online classes, but children have also developed the habit of watching electronic products, such as mobile phones, tablets, and TVs. So many parents are anxious about their children's eyesight. Are there any electronic products that are more eye-protecting? Personally, I think from the perspective of protecting eyesight, there are several issues that must be considered. Let's talk about it today.

01. Choose a larger screen as an alternative

A bigger screen is definitely better. In fact, think about traditional TVs. There is a reference requirement for the best viewing distance. For example, this is a reference table for the best distance. We can see that for the screen, a certain distance must be maintained to get the best viewing effect.

Or follow this table to distinguish the best viewing distances at different resolutions

Mobile phones are also large screens for interaction. In fact, it is more appropriate to keep a longer distance from the screen. However, for children, they can't help but get close to the screen, so in fact, not only the viewing effect is not guaranteed, but also strong light enters the eyes, affecting vision.

Therefore, I suggest that it is better to equip children with a large screen. After all, many smart TVs now have a screen projection function, which can project the content of the mobile phone to the TV, so that children can keep a certain viewing distance.

Of course, based on the large screen, some screen parameters are also worthy of attention. For color screens, there are two main points, namely: blue light and flicker.

Let’s talk about the hazards of blue light and flicker.

02. Reduce blue light

Blue light is a concept that has been mentioned frequently in recent years. Blue light is high-energy visible light with a wavelength of 435±20nm. It is also the light with the highest energy in the visible spectrum, so it is called HEV light (High-energy visible light).

Blue light not only exists in sunlight, but also exists in large quantities in the background light sources of digital electronic devices such as mobile phones, LEDs, and computers.

In recent years, due to the widespread popularity of screen electronic products and the widespread emission of HEV by electronic products, there has been a lot of discussion about the impact of blue light on human health, especially vision, including photochemical damage, photomechanical damage, photothermal damage, etc. For example, studies have found that a large amount of blue light passes through the refractive medium of the eyeball and reaches the retina, which may induce the formation of lipid peroxides and excessive production of reactive oxygen free radicals, thereby having a certain impact on cells in structures such as the retina, increasing retinal-related diseases such as retinitis pigmentosa and age-related macular degeneration [1].

Therefore, blue light has become a major concern for many products, most notably in the field of eyewear, where many high-end lenses are coated with other processes to filter blue light, to prevent people who have long-term contact with screens from being affected by excessive blue light. Of course, in recent years, there have also been related industrial technologies to actively reduce blue light from displays.

03. Reduce flicker

Flickering is when you look at the screen of another appliance through the screen of one appliance, and a bright line will appear on the screen of the other appliance from the bottom to the top of the screen, and then appear from the bottom again. This goes on infinitely, giving us the feeling that the image is flickering. I believe everyone has experienced this situation when taking pictures of the screen with a mobile phone, just like the left side of the picture below, there will be a bright line passing through the display seen on the mobile phone screen.

The main problem that causes flicker is the alternating current. Since the alternating current is constantly changing, the light intensity of the light source will change over time, resulting in flicker on the screen.

Long-term flicker not only affects visual comfort, but also causes some physiological diseases, such as migraines. Therefore, solving flicker is an important idea [2]. The solution is to use direct current power supply. As time goes by, the voltage amplitude and direction of direct current will not change.

Therefore, by adding certain processing measures to the alternating current, such as transformer + rectifier and other facilities, it can be converted into a constant current, so that the flicker phenomenon can be reduced as much as possible, thereby reducing the impact of flicker.

In general, for monitors, big is king. On this basis, if blue light and flicker can be reduced, the eye protection effect can be improved. These are also some points worth paying attention to when choosing a monitor, especially for children.

1 Zhang Chu, Zou Yuping. Research progress on blue light damage to retina and its protective effect. Chinese Journal of Ocular Trauma and Occupational Eye Disease, 2012, 32 (6): 476-480

2 https://headaches.org/2007/10/25/light-and-sensitivity/