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I wanted to address the topic of screen time because it has come up a few times. A number of parents have asked if it is okay for young children to look at the computer? Will it harm their eyes? What are the concerns that we should be aware of? This was a topic of concern for me as well when my children were little.
Myopia (short-sightedness) runs in my family and I have always been told that too much TV is bad for your eyes. Somewhere along the way, that warning extended to include computers. Being myopic and a heavy user of computers to boot, it made me very worried that my boys might also develop vision problems. To understand the nature of the problem, I did a little research and this is what I learned…
Screen Time and Myopia
It turns out that it is not too much screen time that causes myopia. Aside from genetics, the other risk factor for myopia is not spending enough time outdoors. This is because:
- Outdoor light intensity causes the pupil to constrict allowing for a larger depth of focus. The range in which objects appear clear is greater and there is less blurring of images.
- In response to intense light, the retina of the eye releases the neurotransmitter dopamine which inhibits growth (myopic eyes are longer from front to back than normal eyes). This suggests that the higher intensity light from being outdoor inhibits the growth of the eye and minimizes the chance of myopia.
bright outdoor light helps children’s developing eyes maintain the correct distance between the lens and the retina — which keeps vision in focus. Dim indoor lighting doesn’t seem to provide the same kind of feedback. As a result, when children spend too many hours inside, their eyes fail to grow correctly and the distance between the lens and retina becomes too long, causing far-away objects to look blurry.Aamodt and Wang – NY Times
Even though myopia is an inherited condition, it appears that it could be prevented if children are given enough time in natural sunlight. How much time do you need to spend outdoors to make it effective? The research indicates 2 hours a day will reduce the likelihood of developing myopia by 4 times compared to those who spend an hour or less.
- Myopia Prevention and Outdoor Light Intensity in a School-Based Cluster Randomized Trial – Opthalmology
- Animal models in myopia research – Clinical and Experimental Optometry
Is Too Much Screen Time Bad for the Eyes?
The short of the long is: no. At least, nothing that is permanent.
According to James Salz, a University of Southern California eye doctor and spokesperson for the American Academy of Ophthalmology, there’s no evidence that there is any long-term damage from reading on a screen. Too much screen time, however, can result in eye strain (also known as Computer Vision Syndrome) but the effect is temporary and reversible.
Rosenfield blames this not necessarily on screens, but on small print and shorter distances between our eyes and the material being read. Smartphones and tablets may make eyestrain worse because we typically hold them closer to us and more directly in front of our faces than we do books.Popular Science
- Not blinking enough – we tend to blink less when we stare at a screen. Blinking wets the eyes with tears and when we don’t blink enough, our eyes get dry and sore.
- Looking too high – the position of the computer screen is usually higher than when reading from a book. When you look down to read a book, more of your eyes are covered by your eyelids which help to protect them from drying out.
- Holding the screen too close to your eyes – this is more relevant to handheld devices, but in general, we tend to hold our smartphones much closer to our eyes than we do a book. This forces the eyes to work harder to focus at such a close distance leading to eye fatigue.
- Screen brightness – if your the brightness of your computer screen is too dark or too bright, your eyes work harder to make out the images on the screen.
Those most at risk are individuals who are continuously on the computer for more than two hours everyday.
What are the Symptoms of Computer Vision Syndrome?
- Eye discomfort
- Itchy eyes
- Dry or watering eyes
- Burning sensations
- Changes in color perception
- Blurred vision
- Difficulty focussing
- Sensitivity to bright light
- Eye fatigue
How to Manage Computer Vision Syndrome
There are a few things we can do to minimise the risk for developing Computer Vision Syndrome:
- 20-20-20 rule – Every 20 minutes, look 20 feet away for 20 seconds. You should also take breaks away from the computer every two hours.
- Screen position:
- Position your computer so that the top of your computer screen should be no higher than eye level. The aim is for your eyes to be looking straight or slightly down.
- It should be 18-30 inches away from your eyes. You can increase the font size on your handheld devices to help you keep them further away from your eyes.
- The screen should be tilted back 10 to 15 degrees.
- Blink! Try to remember to blink more often. If you find your eyes getting tired, blink rapidly to help your eye muscles relax.
- Reduce glare:
- Make sure there is no light reflecting off your screen’s surface.
- When reading, it is preferable to use a reader that mimics the pages of a physical book, or black text displayed on a gray background which reduces the contrast (readers like the Kindle Paperwhite).
- Avoid using computers or handheld devices in total darkness.
- Eye exercises:
- Slowly make a figure-eight with your eyes
- Move your eyes up and down and from side to side in an open space
- Massage the areas around your eyes (not on top of your eyes, but the muscles around them)
- Hold your thumb a few inches in front of you. Practice switching your eye focus between your thumb and an object at least 20 feet away from you. Working your eyes by making them look at something near and far helps them get stronger.
Where did the advice that TV is bad for your eyes originate from?
So where did the advice that TV is bad for your eyes originate from? It goes as far back as 1960s:
The warning about TV being bad for the eyes seems to have originated in the early 1960s. It was at this time when televisions became common household appliances, and families began to spend more time watching TV programs. Television was still a mystery to most people in the 1960s, and it was widely regarded that a box full of wires, vacuum tubes and mysterious electrical components could not be safe.
This notion was only intensified after one of the largest TV manufacturers, General Electric (GE), admitted that some of its sets were emitting high levels of dangerous X-rays. However, this occurred because of a factory error, which was corrected shortly after being discovered. To protect the public, GE and other TV manufacturers began using leaded glass in the screens that prevented X-rays from escaping.
When GE admitted that excessive X-rays were released, they also warned parents not to allow children to sit too closely because the radiation that can extend a couple of inches away completely dissipates after only a few more inches. Corroborating studies also suggest that eye damage could only occur from television radiation by staring at an unprotected vent no more than an inch away for over an hour.
While there may have been some basis for the warning at one point, it appears it is no longer a relevant concern.