1、Harmful to eyes: Harmful blue light have extreme high-energies, they can penetrate crystalline lens to retina directly, induce atrophy of retinal pigment epithelium or even death. Death of light-sensitive cells will lead to diminution of vision or loss completely. This kind injury is irreversible. Blue light will also induce maculopathy. Part of blue light will be absorbed by our eyes lens and gradually form cataracts. Most blue light can penetrate our eyes lens, especially children, cause their eyes lens are more clear thus can't block harmful blue light effectively, make them more prone to macular disease and cataracts.
2、Asthenopia: Because the wavelength of blue light is short, the focus point is not on the retina center, but a bit further in front of it. In order to see clearly, eyes need to be in a state of tension for a long time which will induce visual fatigue. Being in asthenopia too long may cause deepen myopia, double vision, attention distraction...etc, will bring lots of trouble to our study and work.
3、Bad Sleep: Blue light will inhibit the secretion of Melatonin, an important hormone that affects sleep and is known can promote sleep and regulate jet lag. This can also explain why you will have poor sleep quality or be difficult to fall asleep if you play cell phone or tablet before go to bed.