We were born to have hunter-gatherer eyes, designed to switch focus rapidly between long-distance tasks, such as spotting game on the horizon, and close-up tasks, such as identifying berries. But while human eyes have stayed the same, the modern world and the way we look at it has changed dramatically. In the last two decades, practically all our work and most of our leisure has switched the focus of our vision to just one distance – arm’s length.

Now, our eyes are fixed on a screen. We work for hours at a computer and, when we’re not running, many of us spend our free time texting, playing with mobile apps, or watching a film on our iPad. Our eyes are fixed at screen-distance and we spend hardly any time using our vision in the flexible, focus-shifting way it was designed.

“We each spend an average of 2,740 hours – that’s three and a half months – each year staring at a screen,” says Adrian Knowles, spokesperson for the Eyecare Trust. “Research also shows office workers spend an eye-watering 128,740 hours staring at a screen during their working lifetime. So it’s probably no surprise that 90 per cent of VDU [visual display unit] users say they regularly suffer screen fatigue. When you look at something that’s a set distance from the eyes for so long, you are asking your eye muscles to work incredibly hard – and they will eventually complain, producing symptoms such as sore eyes and headaches.”

Indeed, intensive screen use can put enormous strain on your eyes and trigger episodes of visual stress. Although screen work doesn’t actually destroy your eyesight, it can trigger a condition called screen fatigue. Typical symptoms include tired or irritated eyes, dry eyes, blurred vision, headaches, double vision, changes in colour perception and sensitivity to light. Optician Nick Atkins says dry eyes are a big problem, especially if you work in an air-conditioned office. Lack of blinking, combined with lack of humidity, triggers an uncomfortable, gritty sensation.

Sight for sore eyes

However, while the symptoms of screen vision fatigue can be irritating and even painful, you won’t actually lose your sight as a result of working long hours at a computer. ‘As far as we know, using a computer doesn’t cause long-term damage to vision,” says Nick Atkins. “But it does aggravate any undiagnosed vision problems that reveal themselves under the strain of long hours staring at a computer, leading sufferers to the false conclusion that the computer was the cause of the problem.”?Adrian Knowles agrees. “It’s a misconception that people who work on computers lose their eyesight quicker than people who haven’t,” he says. “Screen work causes eyesight irritation, not deterioration – and this is manageable by measures such as creating an eye-friendly environment [see box below].” Whether you use a screen or not, it’s inevitable that your eyes will deteriorate with age.

Dr Susan Blakeney, a clinician at the College of Optometrists, says our eyes usually begin to deteriorate from the age of 40.“Called ‘presbyopia’, this is normal, expected age-related long-sightedness caused by the eye lenses gradually losing flexibility,’ she says. ‘Your eyes will inevitably lose their elasticity and the exact age when it happens is down to genetics – not anything you do.” However, its effects may be more noticeable if you work?on screen a lot and suddenly find you can’t see what’s on the monitor as well as you used to.

Eye spy

Staring at a screen can highlight existing vision problems you may have and regular check-ups are crucial to ensure you have the right glasses for computer work. A visit to your optician is also vital for spotting more treatable conditions, such as glaucoma. Self-help measures for screen users are also vital. Make sure your monitor is positioned roughly an arm’s length away from your face and that the centre of your screen is 10 to 15cm below your natural eye level. Move your screen if there is too much reflection from a window and, whenever possible, use fonts bigger than 12pt.

Most of all, remember that your eyes are hunter-gatherer designed and need to be used like this as often as possible. Take full advantage of your running time to exercise your eyes, not just your feet. While you are moving along, consciously switch your focus from one distance to another. For example, look down at the grass or pavement beneath your feet and then up at the horizon. Relish what you can see in the reality beyond the pixels on your screen.

Maintain your eye health

Top tips to keep your eyes healthy

– Create an eye-friendly environment. position your monitor an arm’s length away, keep your eyes level with the top of the screen, use font sizes above 12pt and keep your screen clean.

– Get your eyes checked regularly.

– Make sure you blink to keep your eyes moist.

– Take a screen break every 20 minutes. Look up at an object in the distance – then hold a finger in front of your eyes and look at that. Switch between the two at least five times.

– Try ‘palming’ exercises. close your eyes and place your palms over them. Open your eyes, keeping your palms over them. Gradually move your hands away and allow your eyes to adjust to the light.

– Try eye yoga. Keeping your head straight, look at a point directly ahead. next, lower your eyes to look at the floor, then look up as high as you can. Repeat a few times.

Words by Liz Hollis