Feeds

Why are so many humans near sighted?

Myopia linked to modern life?

Secure remote control for conventional and virtual desktops

Also in this week's column:

Why are so many modern humans near sighted?

Asked by Alan Harper of Oakland, California, USA

The eye receives rays of light and bends them so that an image is resolved on a small point of the retina. But things can go wrong.

If the rays focus in front of the retina, the person has myopia (aka near-sightedness or short-sightedness) and suffers blurred vision of distant objects. But if the rays focus at a point behind the retina, the person has hyperopia (aka hypermetropia, far-sightedness or long-sightedness) and suffers blurred vision of nearby objects.

According to Dr Stephen Miller, director of the clinical care centre of the American Optometric Association in St Louis, "the shape of the eyeball and the focusing power of the lens and cornea help determine focus, but the angle at which light rays hit the eye plays a role".

"Light comes into the eye from all directions. Rays entering the eye at an angle from above or below would tend to focus somewhere before or behind the centre of vision. Those rays coming in essentially perpendicular to the eye, on the other hand, would tend to be focused more directly on the retina, providing a clearer image of what one is looking at."

Myopia occurs in at least seven different forms, occurs in varying degrees of severity, and can first develop in infancy, youth, or adulthood. The prevalence of myopia varies from country to country. Depending upon how it is defined, myopia rates are as high as 70 to 90 per cent in Asia, 30 to 40 per cent in Europe and the US, but only 10 to 20 per cent in Africa.

A 2005 study published in Optometry and Vision Science found that slightly more than 50 per cent of UK first-year university students are myopic.

School myopia appears during the childhood school years. This form of myopia is attributed to use of the eyes for close work at school.

As humans use their eyes more and more in close activities (reading, computers, video games, television, and so on) in our modern world, it's not surprising there is so much myopia.

Stephen Juan, Ph.D. is an anthropologist at the University of Sydney. Email your Odd Body questions to s.juan@edfac.usyd.edu.au

Boost IT visibility and business value

More from The Register

next story
Our LOHAN spaceplane ballocket Kickstarter climbs through £8000
Through 25 per cent but more is needed: Get your UNIQUE rewards!
Cutting cancer rates: Data, models and a happy ending?
How surgery might be making cancer prognoses worse
Boffins ID freakish spine-smothered prehistoric critter: The CLAW gave it away
Bizarre-looking creature actually related to velvet worms
CRR-CRRRK, beep, beep: Mars space truck backs out of slippery sand trap
Curiosity finds new drilling target after course correction
SpaceX prototype rocket EXPLODES over Texas. 'Tricky' biz, says Elon Musk
No injuries or near injuries. Flight stayed in designated area
Brit balloon bod Bodnar overflies North Pole
B-64 amateur ultralight payload approaching second circumnavigation
Galileo, Galileo! Galileo, Galileo! Galileo fit to go. Magnifico
I'm just a poor boy, nobody loves me. But at least I can find my way with ESA GPS by 2017
Astronomers scramble for obs on new comet
Amateur gets fifth confirmed discovery
prev story

Whitepapers

Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
5 things you didn’t know about cloud backup
IT departments are embracing cloud backup, but there’s a lot you need to know before choosing a service provider. Learn all the critical things you need to know.
Why and how to choose the right cloud vendor
The benefits of cloud-based storage in your processes. Eliminate onsite, disk-based backup and archiving in favor of cloud-based data protection.
Top 8 considerations to enable and simplify mobility
In this whitepaper learn how to successfully add mobile capabilities simply and cost effectively.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?