Studies have shown that we spend an average of 6-8 hours looking at screens. If we take an average of 7, that's 43% of our waking hours.

Over the course of 75 years, that's 191625 hours, or 21.88 years. Office/knowledge workers, Millennials and Gen Z might allocate 25 years of their life to looking at a screen.

We know that increased screen time is linked to insomnia, neck and back pain, reduced physical activity, addictive behaviours, social isolation and other adverse health consequences. What about our eyes?

As a dual-eyed human who enjoys looking at things, yet spends almost every waking hour staring at a screen or fixing tiny objects, this topic is important to me. 

Screens omit a lot of blue light. Early research in animals suggested that excessive blue light exposure could damage some sensitive nerve cells in the retina.

This resulted in countless articles being published, claiming that screens could make you blind.

Subsequent research has failed to validate these claims: Human eye cells do not break down when exposed to normal amounts of blue light.

If you know how to read studies and interpret data, you will be very familiar with the ways in which the media draws false conclusions, gives unhelpful recommendations, and generally spews out misinformation to create controversy and/or increase site traffic.

It's not just the media though. Manufacturers of blue blocker glasses often cite these early animal studies to support some rather far-fetched claims on how their products can prevent retina damage.

There is currently no evidence that digital screens cause damage to the human eye.

Blue light is simply part of the visible light spectrum - whether it comes from a screen or the sun - blue light is blue light.

We expose our eyes to 100,000 times more blue light on a sunny afternoon outside than we do looking at a computer screen.

Screens do not emit sufficient levels of UV radiation to cause macular degeneration (They don't give you sunburn either, by the way).

However, screen time can induce other, more acute visual problems - most of which are classified under "Computer Vision Syndrome".

Symptoms include:

> Eyestrain

> Headaches

> Blurred vision

> Dry Eyes

> Neck and shoulder pain 

Most people will have experienced one or more of these symptoms. But note that these symptoms don't typically occur in isolation, purely as a result of looking at screens:

> Eyestrain: Focusing on close up objects for a prolonged period.

> Headaches: Poor posture, dehydration, allergies, illness etc. Constantly looking at any object up close.

> Blurred vision: This can be caused by a number of health issues such as glaucoma, eye infection or even high blood sugar.

> Dry Eyes: Cold, dry environments, air conditioning or heating. 

> Neck and shoulder pain: Poor posture or an acute injury.

So what can we do to mitigate any possible negative effects on our eye health as a result of looking at screens?

> Remember to blink. Studies have shown that we blink less when looking at screens. Blinking keeps the cornea lubricated and removes debris. It also brings nutrients and minerals to the surface of the eye  to maintain a protective, lubricating film.

> Our eyes relax and our pupils dilate when looking at things farther away.

Use it or lose it: Training eyes to look at things up close but not far away can lead to short-sightedness.

Maybe this is why stereotypical nerds wear glasses - because they read books all day.

Good protocols to improve farsightedness include taking a 20 second break from a screen/book every 20 minutes, and taking a 5-10 minute break every 90 minutes to focus on something far away - preferably outside.

My personal recommendations are to use lunch breaks to get away from screens, and to consume more audio-only content like audiobooks or podcasts, preferably whilst walking outside.

> Make it easier to see what you're doing: Use a device with a high resolution display. Increase text size. Use a bigger screen or monitor (don't read and write on a phone). Wear glasses if you need to.

> Make sure that your workspace is well ventilated, with adequate humidity. This should prevent dry eyes.

Note how all of these issues and their solutions can apply to reading a book in the same way that it can to looking at a screen.

Screens will almost certainly not damage your eyes directly. If you do the four things mentioned above, you really shouldn't have to worry about the indirect effects of screen time on your eye health.

Other important things related to eye health (but beyond the scope of this post) include adequate nutrition, hydration, posture and stress management.

The impact of screens on our circadian rhythm and sleep quality is well documented and should be taken seriously. We wrote about this here.

If you read the whole post - well done! Reward yourself with a 20 second break from your screen.

TL;DR - look out over the horizon every once in a while.

Disclaimer: This is not medical advice. Consult your doctor or optometrist for any matters related to eye health - not your phone technician.