We spend more and more time each day in front of our computer screens or other electronic devices. According to one study, 60% of us spend more than six hours a day in front of an electronic screen.

Compared to the cathode-ray tube screens of yesterday, today's displays use powerful light sources such as light-emitting diodes (LEDs). LEDs are energy-efficient: they cost less to produce, last longer, and consume very little energy. However, they emit more blue light, or light waves between 380 and 500nm. Visible light is made up of all the colours of the rainbow. Towards the blue end of the scale, the light waves are shorter and are high in energy. Towards the red end of the scale, the waves are shorter and less high in energy. Blue light is also known as high visible energy.

So why should you worry about the blue light emitted by electronic displays? First, this type of light penetrates all the way to the back of the eye, dazzling and tiring the eyes. Secondly, blue light can disrupt your circadian sleep/wake rhythms. Spending too much time in front of a screen before going to bed can interfere with your sleep patterns. Finally, like ultraviolet light, exposure to blue light may constitute a risk factor for macular degeneration.

So what can you do to reduce these undesirable effects? If you spend long hours in front of a screen, there are anti-reflective coatings that partially block out the blue light and reduce eyestrain. Of course, they do not block out all blue light, since that would affect colour perception. But by controlling the amount of blue light that reaches the eye with a special eyeglass lens coating, you can preserve your normal colour vision and increase your comfort when using screens. Certain high-quality sunglasses come not only with UV but also blue-light filters to better protect your eyes against those harmful rays that damage your retinas.

My advice: If you are a heavy user of electronic devices or if you spend a lot of time outdoors, ask for a blue-light filtering coating on your clear glasses and sunglasses. You will both gain comfort and keep your eyes healthy!

Jahel St-Jacques, O.D., Optometrist