Generally, scientists say the visible light spectrum comprises electromagnetic radiation with wavelengths ranging from 380 nanometers (nm) on the blue end of the spectrum to about 700 nm on the red end. (By the way, a nanometer is one billionth of a meter — that's 0.000000001 meter!)
Blue light generally is defined as visible light ranging from 380 to 500 nm.
So approximately one-third of all visible light is considered high-energy visible (HEV) or "blue" light.
Virtually all visible blue light passes through the cornea and lens and reaches the retina. Too much exposure to blue light can damage light-sensitive cells in the retina. This causes changes that resemble macular degeration which can lead to permanent vision loss.
Although more research is needed to determine how much natural and man-made blue light is "too much blue light" for the retina, many eye care providers are concerned that the added blue light exposure from computer screens, smartphones and other digital devices might increase a person's risk of macular degeneration later in life.
Because short-wavelength, high energy blue light scatters more easily than other visible light, it is not as easily focused. When you're looking at computer screens and other digital devices that emit significant amounts of blue light, this unfocused visual "noise" reduces contrast and can contribute to digital eye strain.
After cataract surgery you might benefit from eyeglasses that have lenses with a special blue light filter — especially if you spend long hours in front of a computer screen or using other digital devices.