Blue light exposure may increase the risk of macular degeneration. The fact that blue light penetrates all the way to the retina (the inner lining of the back of the eye) is important, because laboratory studies have shown that too much exposure to blue light can damage light-sensitive cells in the retina.
We know less about blue light, as its effects are still being researched. But because blue light is close on the spectrum to ultraviolet light, it's caused alarm and is on the radar of ophthalmologists.We should know that Blue Light is everywhere, and eyes aren’t good at blocking it.
One way to think about blue light and potential retinal damage is to consider the Sun. On a sunny afternoon, it’s nearly 100,000 times brighter than your computer screen. Yet, few human studies have found any link between sunlight exposure and the development of age-related macular degeneration, a retinal disease that leads to loss of central vision.
If being outside on a sunny afternoon likely doesn’t damage the human retina, then neither can your dim-by-comparison tablet.
The color of the sun is white. The sun emits all colors of the rainbow more or less evenly and in physics, we call this combination "white". That is why we can see so many different colors in the natural world under the illumination of sunlight.The sun emits all colors of visible light, and in fact emits all frequencies of electromagnetic waves except gamma rays. This includes radio waves, microwaves, infrared waves, visible light, ultraviolet waves, and X-rays. The sun emits all these colors because it is a thermal body and emits light through the process of thermal radiation. Just like a hot coal or an electric stove element that glows, the sun glows in all colors because of its temperature. That is why incandescent light bulbs emit light that mimics sunlight so well: they contain metal filaments that are heated until they glow in the same way the sun does.The blue light in Sunlight is very few more more less than the digital devices screen light we exposed.
The another hand ,you sit in front of computer to reading or learning ,your eyes are staring at the screens for 8 -10 hours.Have you ever stared at Sunlight in that way?And the most important is LONG TIME （8-10 hours）.After long time ,more and more blue light enter into our eyes.the amount always keep increasing. At the time you leave computer,most times you will begin to watch TV or enter your LED light bedroom.All of these devices make blue light full of our life.Anyone who work on computer or iphone or any other eletronic device should take measures to protect eyes from blue light.