With the increased presence of digital devices in our modern lives, we have been hearing more about blue light and its effects. We recently did a podcast with The Harley Street Edit about blue light and eye sight which you can listen to here. Read further to find out what blue light is and the effect it has on your eyes and wellbeing.
Key points about blue light
Sunlight consists of red, yellow, green, and blue light rays as well as all the shades in between. The energy and wavelength of the individual ray determines the colour.
Light rays with long wavelengths contain less energy, and those with short wavelengths have more energy.
Rays on the blue end of the spectrum have shorter wavelengths and therefore more energy are known as high energy visible light (HEV).
Visible blue light has both benefits and dangers
Blue light (HEV) has enough energy to create free radicals. Free radicals are highly reactive molecules that cause cell damage, some of which the body cannot repair (e.g. damage to your cell’s DNA).
The purpose of antioxidants like lutein and zeaxanthin (our macular pigments) is to stop this from happening. This is why we should eat more foods with antioxidant properties, specifically dark and brightly coloured fruits and vegetables like kale, spinach, avocados and blueberries with lots of lutein and zeaxanthin. They help you to stay healthy and lessen the negative effects of this process.
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.
Research has shown that lenses that block blue light with wavelengths less than 450 nm (blue-violet light) increase contrast significantly. Therefore, computer glasses with yellow-tinted lenses may increase comfort when you're viewing digital devices for extended periods of time.
So, is all blue light bad for you? What if you block all blue light, all the time?
A certain amount of blue light exposure is essential for good health. Research has shown that high-energy visible light boosts alertness, helps memory and cognitive function and elevates mood.
Light therapy is used in the treatment of seasonal affective disorder which involves bright white light that contains a significant amount of HEV blue light rays.
Also, blue light is very important in regulating the circadian cycle (body's natural sleep/awake clock). Exposure to blue light during daytime hours helps maintain a healthful circadian rhythm. But too much blue light late at night (reading a novel on a tablet computer or smartphone at bedtime, for example) can disrupt this cycle, potentially causing sleepless nights and daytime fatigue.
Do I need blue light blocking lenses?
We would recommend a blue control lens if you are doing a significant amount of screen based work. We offer Hoya’s Blue Control coating on our prescription lenses, which has all the benefits of Hoya’s premium Hi-Vision Longlife coating, and neutralises the blue light emitted by digital screens, hence reducing eye fatigue, eye strain and sleeplessness. Additional benefits include the reduction of glare and enhanced viewing contrast