The Side Effects of Staring at a Computer Screen for Too Long

By Alex McIl – 1st Feb 2022

We all do it, and deep down we all know it is bad for us. It is late at night, you are ready to fall asleep, but you can’t because you have been blasting blue light directly into your eyes while staring at your phone’s screen in the dark.

Once you do fall asleep, you wake up to go to work and spend at least an other 8 hours on your computer.

So what exactly are the side effects of staring at a computer screen for too long?

Man glaring into a computer screen and mobile device

Evidence shows that nearsightedness (Myopia) can increase by up to 80% [R] in young people due to excessive screen time. This in itself should be a caution to take this issue seriously.

When we consider that since the 70s Myopia has doubled, it is likely due to the increase of computer use in households.

Personal Experience With Too Much Screen Time

I feel I have affected my eyes through computer use, something the crept up on me after 5 years of looking at a screen for about 5-7 hrs per day.

The first thing I noticed was how long it took for my eyes to adjust its focus when looking at a distance. Then I found it hard to distinguish colors, particularly in the blue & purple range. This was not ideal considering I was doing some design work, and noticing contrasts was difficult.

After a while I noticed floaters in my eyes getting worse. Often I would have a floater affecting my peripheral vision to the point I always felt I was seeing a presence walking by. And lastly, I have since noticed a brown dot in the white of my right eyeball that blurs my site more when I stare at a screen.

Disclaimer: It’s not being said that too much screen time was the direct cause of my eye problems, but I do suspect it certainly doesn’t help the issue.

The 20 20 20 Rule Reminder

This is one rule that I wish I followed. I never really knew about this rule specifically, but it is common sense to take breaks from the screen.

The rule states that for every 20 minutes spent using a screen, you should look at something 20 feet away (6 meter) for a total of 20 seconds.

This helps your eyes focus at various objects at different distances. Essentially, you stop training your eyes to look at a fixed distance constantly.

Realistically though, we get too engrossed in our work to remind ourselves to perform this exercise, so using an app such as the Eye Care 20 20 20 can remind you to do your exercise.

As we are on the subject of honesty, it is unlikely (even with the aid of a 20 20 20 rule for eyes app) you will perform this exercise every 20 minutes. There are times you are engrossed in your work that you simply cannot stop and break the momentum. Being literal about doing it every 20 minutes is not the goal here, just make sure you take enough breaks (that better than no breaks at all).

Does The 20 20 20 Rule Work?

There can be differences of opinions on the effectiveness of this topic. However, you are literally taking breaks from staring a fixed length at an object that’s constantly pumping light into your eyes. This in itself is not a natural process for the human eye, so moving away from it cannot be a bad thing.

How can setting your eyes away from a screen and looking elsewhere in a natural manner be ineffective or harmful?

In short, this can only help and it is always good to give your eyes adequate enough breaks from staring at a monitor for long periods.

How Long Should You Look At A Computer Screen?

The recommended 20 20 20 rule determines at what intervals you should rest your eyes and for how long. However, it does not definitively answer the question, how long should you look at a PC monitor for in a day?

Many do not have much choice in selecting how long they can work at their computer. Simply put, if you have a 9 to 5 job, then you are bound to work those hours and that’s where the 20 20 20 rule can come in handy to help preserve your eyes.

If a freelancer, you have more flexibility with your working hours. I would personally say work at least half your working day using the 20 20 20 rule before taking an hour break, and then completing the second half of the day (while applying the rule again).

However, if you can break your day up further into thirds, then that’s even better because staring at your computer screen all day is really bad!

Computer Screen Filter To Reduce Eye Strain

There are other tactics that can be used to further protect your eyes, or enabling more screen time while limiting eye damage, which is why there isn’t a definitive answer as to how long you should be staring at a screen in any given day.

Here are those factors:

1. Computer screen filter to reduce eye strain

This can come in two forms: a physical filter that you place over your screen that reduces blue light, or a setting on your computer.

2. Proper room lighting conditions

This can be a little tricky to get right. You do not want your screen lighting to be brighter than your surroundings. At the same time too much light can cause glare on your screen which adds stress to your eyes.

Typically if you can find lighting that is about half that of regular office lighting, that would be ideal. On top of that, using full spectrum” fluorescent bulbs replicates the spectrum the sun emits.

3. Lowering color temperature of monitor

Lowering your screens color temperature means that less blue light is emitted, which is linked to more eye strain.

4. Increase refresh rate

Your screen flickers, and although you may not physically notice it, it does add stress to your eyes. The higher you set the refresh rate, the less flickering.

how to increase screen refresh rate for reduced flickering

Is Computer Vision Syndrome Permanent?

Before answering this let’s look at the definition of Computer Vision Syndrome:

Computer Vision Syndrome is a group of eye & vision issues caused by extended computer or handheld device use.

This syndrome is the result of over using your eye muscles which can cause a host of symptoms such as red eyes, headaches & double vision. As the use of computers and digital devices increases, the age of people getting diagnosed are getting younger.

Symptoms of CVS

  • Red eyes
  • Headaches
  • Double vision
  • Dry eye
  • Blurred vision
  • Eye tearing
  • Itchy eyes

It is said there is no evidence that CVS causes any long term damage and this does appear to make sense in terms of the muscle use of the eyes. However, I do wonder if the constant glare of light shining into the eye may (in time) cause some impact?

Not only that, as the eye is a muscle, if you train it to look at one focal length for extended periods of time, does the muscle not adapt to this habit and possibly affect how it focus at other focal lengths?

Final Thoughts!

Although it is generally believed that screen usage is unlikely to damage your eyes, I do wonder if it changes some characteristics to your eyes’ functions.

As someone who was always long-sighted, I am finding it very hard to focus at objects at a distance, and furthermore, everything does look blurred which probably impedes the focusing of the eye.

Again, I cannot say this is the result of too much screen time, as I am getting older and other issues could be the cause. However, some doctors believe heavy computer use causes the optical power of the vertebrate to change.

Therefore, it can only be a good idea to at the very least give yourself sufficient breaks from your screen… simply put, it cannot hurt!


Resources & References

[R] – Screen time linked to risk of myopia in young people