alive logo

Screen Time

Too much can harm our vision


Screen Time

Regular peering into the digital world may lead to extreme computer eye strain, also known as computer vision syndrome or CVS. Learn how to spot and prevent it.

Whether it’s for work or for fun, people are spending more time than ever in front of digital screens. But countless hours focused on a computer or an e-reader can take a serious toll on one of our most precious assets: our eyes.

“We all do a lot of staring at screens,” says optometrist Paul Geneau. “People tend to tough it out when they’re working on the computer: they’ll spend hours at it without taking a break. Then when they step away they realize their eyes are bothering them.”

Regular peering into the digital universe may lead to computer vision syndrome (CVS), which can severely impact visual comfort and temporarily impair functioning.

What is CVS?

The term “computer vision syndrome” refers to a range of eye and vision problems associated with prolonged use of computer or other digital screens.

Although it doesn’t result in permanent damage, it’s common, affecting about three-quarters of computer users.

Here’s what happens: the eyes focus well on images that have clearly defined edges and strong contrast between the background and any letters and symbols—say, printed material that has solid black figures on a white background.

But it’s a different story with electronically generated characters. Letters and numbers displayed on a computer screen consist of thousands of tiny dots called pixels. The eyes have a difficult time focusing on pixels and end up straining and relaxing over and over again as a result. This constant flexing of the focusing muscles (those of the ciliary body) can lead to fatigue and spasms.

Other factors can exacerbate CVS: insufficient tear flow; the effects of glare and reflection on the monitor; poor ergonomics and lighting; and the need for vision correction.

CVS is most prevalent in people over age 40, when the ability to focus on closer objects begins to wane.

According to the Canadian Association of Optometrists, the number of eye complaints related to computer use is higher than it was five years ago. No wonder, given the proliferation of more sophisticated smart phones and laptops, the introduction of “tablet” computers, and the ever-growing popularity of social networking and media.

In fact, Canadian baby boomers spend nearly eight hours a day in front of potentially eye straining devices such as computers, cell phones, e-books, and other wireless devices, according to a 2009 Léger Marketing survey.

Preventing CVS

Even for those who spend their work days and much of their downtime glued to a laptop or a cellphone, much can be done to avoid computer vision syndrome.

Blink often
Blinking is crucial. People normally blink about 12 times per minute, but when they’re in front of a computer, that number drops to five. Infrequent blinking makes eyes dry. Lubricating eye drops can also help.

Use the 20-20-20 rule
Take a break by practising what Geneau calls the 20-20-20 rule: every 20 minutes, look away from the computer for at least 20 seconds and fix your gaze on something about 20 feet away.

Avoid glare and reflection
It’s important to be aware of glare and reflection, which can make the eyes strain more than necessary, from office lighting and sunlight. Try to have your computer beside a window, not directly in front of or behind one. A glare filter, which attaches to the computer screen, can also help.

Adjust window blinds so that the sun isn’t shining directly onto your monitor or into your eyes.

Turn off or lower overhead lights that are overly bright, and make sure desk lamps aren’t turned toward the screen or shining in your eyes.

Position screens ergonomically
Proper positioning of computer or digital equipment is vital. A computer screen should be between 20 and 26 inches (50 and 65 cm) away, and the first line of text should be at eye level. If you use a document holder, make sure it’s as close to the monitor as possible.

Get your eyes checked
Sometimes people need vision correction. Being far- or nearsighted, having astigmatism, or wearing glasses can all make computer use less comfortable and efficient. Regular eye exams are a must.

In some cases people need eyewear that’s designed specifically for computer use. Reading glasses correct near vision only, while computer screens should be about an arm’s length away. Lenses that correct at the intermediate distance are required to adequately focus on the computer screen.

Computer glasses should have the proper prescription measured at the working distance from the screen as well as a computer tint; an ultraviolet tint; antireflective coating; and, if necessary, prism, which enables the eyes to work as a team as opposed to individually.

Supplements for sight

Certain natural supplements can enhance the health of our eyes and support our vision.

Vitamins C and E and beta carotene are especially beneficial when combined with zinc, according to the massive 11-centre Age-Related Eye Disease Study. Published in 2001, it concluded that these supplements prevented vision loss in those at high or moderate risk of vision loss from age-related macular degeneration. Vitamin C in particular, when taken long term, has been linked to a reduced risk of cataract extraction.

Ginkgo biloba
The herb seems to improve pre-existing damage to the visual field in people with normal tension glaucoma

This dietary carotenoid, found in certain brightly coloured fruits and vegetables such as mangoes, carrots, squash, and kale, is a dominant pigment of the macula. It could play a role in protecting the retina from photic damage.

Omega-3 fatty acid
This essential fatty acid seems to protect against retinopathy, the deterioration of the retina.

Said to improve night vision, the extract contains anthocyanosides, which might protect the retina and prevent cataracts.

What are the symptoms of CVS?

The most common signs of CVS are:

  • eye strain
  • eye fatigue
  • dry eyes
  • burning sensation in the eyes
  • photophobia, which is an oversensitivity to light
  • blurry vision
  • double vision
  • headaches
  • shoulder, back, or neck pain
  • squinting to read digital content
  • letters on the screen seeming to run together
  • “halos” appearing around objects on the screen
  • driving is harder or night vision is worse after computer use


Your winter wellness game plan

Your winter wellness game plan

Stay healthful when the weather outside is frightful

Joshua Duvauchelle

Joshua Duvauchelle