At a glance:
- Blue light is a short wavelength, high energy frequency of light
- The sun is the most prominent source of blue light
- Blue light may also be emitted by electronic devices such as fluorescent lights, LED TVs, computer screens, smartphones and tablets
- Blue light is essential to good health and maintaining a healthy circadian rhythm
- Blue light is associated with damage to the retina
- Blue light may also be associated with digital eye strain
Visible light from any source is far more complex than it may first appear. White light, such as light from the sun or a fluorescent tube is made up of a rainbow of colours - red, orange, yellow, green, blue, indigo and violet light.
Each of these colours carries a different amount of energy and has a different wavelength. Red light, for example, is low energy and has a long wavelength. At the opposite end of the spectrum, blue light (covering blue, indigo and ultra violet) has a short wavelength and far more energy.
To put it another way, the light towards the red end of the spectrum has wavelengths akin to radio or infrared, whereas towards the blue end the wavelength is that of UV radiation, x-ray and even gamma rays. The shorter the wavelength of light, the more damaging it can be to cells in the human body.
The wavelength of light is measured in nanometers (nm). A nanometer is one billionth of a meter. The wavelength of visible red light is around 650-700nm and blue light sits between 400 and 500nm.
Blue light is sometimes referred to as High Energy Visible (HEV) light and comprises around one third of all visible light.
Schedule an appointment with an optometrist for an eye test today.
Sources of Blue Light
The sun is far and away the biggest source of blue light, but it can be found everywhere. Potential sources of blue light include:
- Fluorescent light tubes
- Compact Fluorescent Light (CFL) bulbs
- LED bulbs
- LED TVs and screens
- Computer monitors
- Smartphones
- Tablets
The amount of blue light emitted from digital devices is small compared to that of the sun but there is potential that electronic blue light exposure may ultimately be harmful due to proximity and the amount of time spent in front of them. There is little in the way of legitimate scientific study about these concerns.
What Can Blue Light Do To The Eyes?
Blue light isn’t necessarily bad. The opposite is in fact true. Limited exposure to blue light is essential to good health. Research has shown that exposure to blue light may help with mood, energy levels, alertness and cognitive function, and blue light may be used to help treat some forms of Seasonal Affective Disorder .
Blue light is also essential for maintaining a healthy sleep/wake cycle (circadian rhythm). Exposure to blue light during the day helps maintain these rhythms and too much exposure at night, such as watching TV in bed or using a tablet, may make sleeping more difficult. Blue light also helps control pupillary response to light.
All that said, exposure to blue light may also cause damage to your eyes. The eye is very good at filtering UV radiation but it can’t filter visible blue light. This light is free to pass through the cornea and lens and enter the retina at the back of the eye.
Studies have shown that blue light may cause damage to the light sensitive cells in the retina and that this damage resembles that caused by Age-Related Macular Degeneration (AMD) . AMD is a leading cause of vision loss in Australia. Exposure to blue light from the sun is the most obvious cause of retinal blue light damage, but there is some fear that electronic blue light may be an additional risk factor for the condition.
Electronic blue light may also cause digital eye strain thanks to how short frequency light scatters. Short frequency light scatters more easily than other wavelengths of light, causing visual noise, reducing contrast and thus making it harder for people to focus. This may be a cause of digital eye strain. Digital eye strain, sometimes also known as computer vision syndrome may also be related to proximity to the screen and focusing on a single focal length for an extended period of time.
Protecting Yourself From Blue Light
Research has shown that blue light filtering lenses (up to 450nm) may help increase screen contrast and reduce instances of digital eye strain. Blue light filters are also available for all manner of screens, both as physical screens or as apps that reduce the amount of blue light projected by the screen.
Protecting your eyes from the sun is far more important for your overall eye health. Wearing sunglasses that block blue light is a good first step, but glasses that wrap around and protect your eyes from the side as well as front are better.
If you wear prescription glasses, prescription sunglasses or transition lenses offer good eye protection. A number of anti-glare treatments also help in filtering blue light.
Refraining from using a tablet or phone within a few hours of sleep may help you maintain healthy circadian rhythms. Taking regular breaks from staring at a screen is an excellent way to minimise eye strain. A number of programs are available on both Mac and PC to blacken the screen for a short time at regular intervals to remind you to take a break or limit screen time.
If you're worried that your child is spending too much time in front of a screen and that their eyes or sleep patterns may be harmed by blue light, turn off their devices and buy then a kids' book .
You only get one pair of eyes, so taking care of them is an important job. The easiest and most convenient way to schedule an appointment with an optometrist for an eye test, for help with eye strain or other eye care needs is to search and book online with MyHealth1st.