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Each day, our lives are all significantly impacted by electronic devices. Have you ever wondered if the blue light from these devices is putting your vision at risk?

Take a moment and think back ten or fifteen years ago. How much of your daily life did you spend using an electronic device? Compare that to your daily use now. There is likely a big increase in daily screen time exposure. Electronic device use has become an almost unavoidable aspect of our daily lives. Smart phones, tablets, computers are the big offenders. Does all of this screen time affect our health? The answer is both yes and no.

The media is full of claims that excessive screen time can cause many health concerns including dry eye problems, digital eye strain, sleep cycle disruption, and potentially macular degeneration among others. These problems are said to be caused from over exposure to “blue light” which is emitted from the screens on electronic devices.

As a result, a new market has developed for special eyewear specifically used for blocking the blue light from electronic devices. Advertisers claim that use of their blue light blocking glasses will protect the eyes from the damaging effects of blue light, even though there is no evidence that the blue light from electronic devices is damaging to the eyes.

What is blue light?

Blue light is part of the visible light spectrum that can be seen with the human eye. It is a high energy, short wavelength type of light. We are and always have been exposed to large amounts of blue light naturally from the sun. It is true that televisions, smart phones, laptops and tablets also emit blue light however, the amount of blue light from electronic devices is a very small fraction of that emitted by the sun.

What does science tell us?

It all comes down to this: consumer electronics are not harmful to the eye because of the amount of blue light emitted. Current iPhones have a maximum brightness of around 625 candelas per square meter (cd/m 2 ). Brighter still, many retail stores have a brightness twice as great. However, these sources pale in comparison to the sun, which yields an ambient illumination more than 10 times greater! (from Harvard medical letter) .

There have not been any valid scientific studies that have found that the blue light from electronic devices is damaging to the human eye.

It is known that some kinds of light can cause eye damage such as ultraviolet light from the sun which includes UVA and UVB light. These wavelengths can cause cataracts, and cancer. There is no measurable UVA UVB light coming from electronic devices.

What does blue light do?

Blue light does have a physical effect on the human body. It stimulates the brain and improves our mood and alertness. Consider how your mood and energy change on a sunny day. Blue light is important in the maintenance of our sleep wake cycles. It wakes us up in the morning, and its disappearance in the evening influences our sleepiness in the evening. Prolonged exposure to this stimulant effect from blue light can interfere with our natural sleep wake cycle and our ability to fall asleep, especially with excessive night time exposure to electronic devices.

What is the cause of the problems associated with screen time?

The American Academy of Ophthalmology states that the reported health concerns are not from the blue light, but the eye strain from prolonged viewing or overuse of digital devices. Long hours of staring at a digital screen can cause eye strain and dry eyes from decreased blinking, but this is due to how individuals use their screens, not blue light coming from the screen.

Dry eyes.

We blink less when we stare at the computer and other devices. Humans blink approximately 15 times per minute, but this blink rate can be cut in half when staring at screens or doing other near work activities like reading.

Eye strain. 

Prolonged use of our eyes for any reason including screen time, driving, reading print or other “near work” activities can cause eye strain leaving a feeling of fatigue and potentially result in headaches.

Protecting the eyes. 

The American Academy of Ophthalmology recommends the following to protect your eyes from strain and overuse:

• Sit 25 inches from the screen.

• Position the screen so you are gazing slightly downward.

• Reduce glare by using a matte screen filter.

• Take regular breaks using the “20-20-20” rule: Every 20 minutes shift your eyes to look at an object at least 20 feet away for at least 20 seconds. 

• Limit screen time to 1-2 hours before bedtime

• Use night mode on electronic devices to minimize blue light exposure.

What about Blue Light eye wear? Are Blue Light Blocking Glasses worth purchasing?

Individual preference is the answer. Many people claim benefits from the use of blue light reducing eyewear. Using these glasses is not thought to be harmful in any way... yet. Future research may shed more light on that topic!

One additional note: Caution with children and screen time.

A few facts from the medical literature regarding children and screen time include the following:

• There is no evidence that screen time damages the eye however, there is an increase in the amount of nearsightedness in children which may be related to the amount of near work activities. 

• A recent research study from Canada found that preschoolers who had more than two hours of screen time per day had nearly an 8-fold increase in Attention Deficit Hyperactivity Disorder (ADHD). 


Will blue light from electronic devices increase my risk of macular degeneration and blindness? April 08, 2019, 10:30 am Updated May 01, 2019, 1:58 pm David Ramsey, MD, PhD, MPH Contributor

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