What is Blue Light and Why Should I be Concerned? Part 1

Part 1: Blue light and Eye Strain

Recent research from The Vision Council found that 90 percent of people use digital devices for two hours a day, while 60 percent are on devices for five or more hours. Of these people, 65% of them report symptoms of digital eye strain.

You’ve no doubt been hearing about blue light, and buzz words like “blue blockers”, “computer glasses” or “Gamer-glasses”.  But what IS blue light? And why should you be concerned?

 Blue light computer eye strain


We asked our panel of optometrists all about blue light, and digital eye strain, and here's what they had to say:

 high energy blue light

Light is made of electromagnetic particles that travel in waves of various lengths. The visible light spectrum is the portion of the light with wavelengths of 400-750 nanometers. UV light is in the wavelength range of 100-400nm. See our blog post on the 5 myths about UV.  The shorter the wavelength, the higher the energy, and the more potential to cause harm. Longer wavelengths are relatively harmless. Blue light is in the visible light spectrum of about 400nm to 450nm. Blue light can penetrate the cornea (clear tissue at the front of the eye) and the lens, and come into contact with the retina. Science links the cumulative exposure to these high energy wavelengths with development of diseases such as cataracts and macular degeneration. 

As light enters the eye, light first interacts with the cornea. On the corneal surface, blue light increases the presence of “reactive oxygen species” or ROS. These create an inflammatory cascade on the front surface of the eye, and cause symptoms of dryness, burning and/or tearing.

 Dry eyes eye strain

Light then enters the eye and goes through the lens. The lens and the muscles around it control the eye’s accommodation (focusing power). The closer an object is, the harder the lens and muscles focus. However, high energy violet / blue light causes a myopic defocus, which causes the eye to focus even harder than they would if you were staring at paper at the same distance. Blue light also causes light scatter and glare, leading to pain and discomfort around the brow and behind the eyes. This is termed “Digital Eye Strain” (DES) or “Computer Vision Syndrome” (CVS). 

 head ache computer vision syndrome

The symptoms of DES/CVS are worsened by 3 main factors: Proximity to the device, Intensity of the light source, and Frequency and Duration of exposure.

Proximity: People (especially kids and teens) tend to hold their phones closer than they would a book. This causes increased demand on our accommodation and convergence (going cross-eyed).

Intensity: is exponentially increased with a decreased distance to the device. I.e., if you hold a device twice as close, you’re getting 4x as much light intensity.

Frequency and Duration: of exposure is the number of times during the day, and how long you’re looking at the device for each time, more exposure = more eye strain.

So what can we do to reduce digital eye strain / computer vision syndrome?

Increase the distance: Make sure you’re not holding your device too close! On multiple monitors at work? Try to push the monitor back, even a few inches helps!

Decrease the intensity: It is always important that your device is at the appropriate brightness for your surroundings. If you’re looking at your computer or phone in the evening, turn down the brightness, or turn them to night mode. In a bright office and can’t do that? Reach for blue blocking glasses! Computer glasses help reduce the blue light exposure to your eyes, thus reducing glare, light scatter, and those head ache symptoms!

Lastly, take breaks! Get up and walk around, look down the hall, or out a window. Something to break your focus and rest those eyes!