What is blue light?
To understand blue light we must first look at the light spectrum. Visible light from the sun consists of a range of different coloured light rays which contain different levels of energy. Sunlight includes red, yellow, green and blue, all in various shades. These different colours have different wavelengths and different levels of energy, as you can see on the light spectrum table below.
Light rays with long wavelengths contain less energy and rays with short wavelengths contain more energy. As you can see rays on the red end of the spectrum have longer wavelengths and, therefore, less energy while rays on the blue end have shorter wavelengths and more energy. These blue rays are sometimes called blue-violet light.
Why is it harmful?
There is a lot of new research that shows a specific wavelength of blue light can cause a number of visual problems. Unfortunately our eyes are not very good at preventing blue light from reaching the back of our eyes. So while UV light is effectively blocked from reaching the retina, the same does not occur with blue light. It passes through the cornea and lens (which so effectively block out the UV light) and reaches the retina. Because of this it may increase the risk of macular degeneration. Some experts are worried that the high usage of digital devices, such as computers and smartphones, may increase a person’s likelihood of developing macular degeneration later on in life. This is especially true in our children’s generation as so much of modern life revolves around the computer screen.
The high energy blue light from computer screens and other digital devices can reduce the amount of contrast. This means that our eyes have to work harder to see the screen and therefore can lead to eye fatigue or what we call digital eye strain. Once again this is very prevalent due to the high usage of computer screens in modern society
The other harmful effect of blue light is it’s effect on sleep patterns. Too much exposure to blue light, especially late at night, can inhibit the release of melatonin which signals to the brain when it is time to sleep. This can lead to sleeplessness and daytime fatigue.
What can I do?
A couple of simple tips to avoid excessive exposure to blue light are to:
- Use minimum brightness on your computer or smartphone screen
- Use apps on your smartphone, such as f.lux, which filter out the blue light
The other option that we recommend is to use a pair of computer glasses that incorporate blue-blocking lenses. These lenses are available with or without a prescription. If you have presbyopia (difficulty reading up close) and usually wear multifocals, then computer glasses give you the benefit of seeing your entire computer screen (keeping in mind that these glasses are specially used for this rather than seeing anything at a distance).
Ask your optometrist which option would best suit you and your needs.