Lifestyle Causes Myopia, Not Genes

Nearsightedness, or myopia is one of the most common vision problems experienced, and it is the most common type of prescription lens worn by those under 30.

It is a problem of the eye that causes light to focus irregularly through the eye and it makes seeing clearly at distances difficult.

Most people that suffer from nearsightedness can see fine up close, and do not require corrective lenses for activities such as reading. While many people suffer from myopia, most do not realize that it is one of the easiest types of vision problems to improve naturally, and preventing the condition from worsening can be easy and inexpensive.

For today’s blog, we have re-printed a very compelling article from the “New Scientist” magazine. The article analyzes the increase in vision problems around the world. It seems the scientific community is starting to come to terms that our lifestyle changes are causing our rapid increase in vision problems.

One of the best things we can do for our visual health is to learn the root cause of our vision problems so we can start preventing them immediately.

As I stated in the Rebuild Your Vision book many years ago, I feel that the medical community should be bound to prevent these problems, yet they still have not taken major steps to do so. Treating the problem still seems to be more of a priority then preventing it in the first place.

To your vision – for life.

Orlin Sorensen

Lifestyle Causes Myopia, Not Genes

New Scientist, Print Edition

Contrary to popular belief, people in east Asia are no more genetically susceptible to short-sightedness than any other population group, according to researchers who have analysed past studies of the problem.

The epidemics of myopia in countries such as Singapore and Japan are due solely to changes in lifestyle, they say, and similar levels could soon be seen in many western countries as lifestyles there continue to change.

“As kids spend more time indoors, on computers or watching telly, we are going to become just as myopic,” says Ian Morgan of the Australian National University in Canberra.

Myopia is on the increase in most places, but in countries such as Singapore it has reached extraordinary levels. There, 80 percent of 18-year-old male army recruits are myopic, up from 25 percent just 30 years ago.

Employers such as the police are having problems finding people who meet their requirements. There is also an increasing incidence of extreme myopia, which can lead to blindness.

There is little doubt about at least one underlying cause. Children now spend much of their time focusing on close objects, such as books and computers. To compensate the eyeball is thought to grow longer. That way less effort is needed to focus up close, but the elongated eye can no longer focus on distant objects.

Religious texts

The argument is about why the rate of myopia is so much higher in east Asia than elsewhere. The conventional view is that people from the region have genetic variations that make them more susceptible. But after reviewing over 40 studies, Morgan and Kathryn Rose of the University of Sydney argue that there is no evidence to support this.

The pair, whose work will be published in Progress in Retinal and Eye Research, use several lines of evidence to debunk the idea that genes can explain the Asian epidemics. For instance, 70 percent of 18-year-old men of Indian origin living in Singapore have myopia, while in India itself the rate is roughly 10 percent.

Another study found myopia rates of 80 percent in 14 to 18-year-old boys studying in schools in Israel that emphasize reading religious texts. The rate for boys in state schools was just 30 percent.

“The simplest explanation is that you have a massive environmental effect that is swamping out the genetic influence,” says Morgan. In other words, given the wrong lifestyle, everyone is susceptible to myopia.

Play sport

And it looks as if those lifestyle changes are beginning to be felt in some western countries too. In Sweden, for instance, 50 percent of children aged 12 now have myopia. It is expected that when these children reach 18 the rate will be more than 70 percent.

“It is an impressive piece of work,” says Karla Zadnik of Ohio State University College of Optometry in Columbus. But if the increase really is due to too much reading, she points out, then lenses that eliminate the stress of focusing on near work should help stop myopia getting any worse. In fact, studies show the lenses are of little help.

But that might be because we have not identified all the lifestyle factors involved, including ones that protect against myopia, says Morgan. For example, children who read less also tend to spend more time outdoors, where better light may reduce the need to focus precisely for near vision. Studies show that children who play sport are less susceptible to myopia.

One group of researchers has even proposed that diet is one of the factors contributing to the rise in myopia. They argue that eating too much refined starch affects the growth of the eyeball (New Scientist print edition, 6 April 2002).

Eye development

But even if there are no big differences between population groups, genetic studies are important, says Christopher Hammond of St Thomas’ Hospital in London. There might be some people whose vision remains perfect whatever their lifestyle.

“If we can identify the genes involved, we have a better chance of understanding the mechanisms involved and developing treatments,” he points out.

In a study of 506 pairs of twins, Hammond found that when you take environment out of the equation, genes account for 87 percent of the variation in short and long-sightedness. The team has identified several genes that may be involved, including PAX-6, which is known to be important in the development of the eye.

Journal reference: The American Journal of Human Genetics (vol 75, p 294)

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