The Sun Is the Best Optometrist

By SANDRA AAMODT and SAM WANG

Published: June 20, 2011

WHY is nearsightedness so common in the modern world? In the early 1970s, 25 percent of Americans were nearsighted; three decades later, the rate had risen to 42 percent, and similar increases have occurred around the world.

There is significant evidence that the trait is inherited, so you might wonder why our myopic ancestors weren’t just removed from the gene pool long ago, when they blundered into a hungry lion or off a cliff. But although genes do influence our fates, they are not the only factors at play.

In this case, the rapid increase in nearsightedness appears to be due to a characteristic of modern life: more and more time spent indoors under artificial lights.

Our genes were originally selected to succeed in a very different world from the one we live in today. Humans’ brains and eyes originated long ago, when we spent most of our waking hours in the sun. The process of development takes advantage of such reliable features of the environment, which then may become necessary for normal growth.

Researchers suspect that 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.

One study published in 2008 in the Archives of Ophthalmology compared 6- and 7-year-old children of Chinese ethnicity living in Sydney, Australia, with those living in Singapore. The rate of nearsightedness in Singapore (29 percent) was nearly nine times higher than in Sydney. The rates of nearsightedness among the parents of the two groups of children were similar, but the children in Sydney spent on average nearly 14 hours per week outside, compared with just three hours per week in Singapore.

Similarly, a 2007 study by scholars at Ohio State University found that, among American children with two myopic parents, those who spent at least two hours per day outdoors were four times less likely to be nearsighted than those who spent less than one hour per day outside.

In short, the biological mechanism that kept our vision naturally sharp for thousands of sunny years has, under new environmental conditions, driven visual development off course. This capacity for previously well-adapted genes to be flummoxed by the modern world can account for many apparent imperfections. Brain wiring that effortlessly recognizes faces, animals and other symmetrical objects can be thrown off by letters and numbers, leading to reading difficulties. A restless nature was once helpful to people who needed to find food sources in the wild, but in today’s classrooms, it’s often classified as attention deficit hyperactivity disorder. When brains that are adapted for face-to-face social interactions instead encounter a world of e-mail and Twitter — well, recent headlines show what can happen.

Luckily, there is a simple way to lower the risk of nearsightedness, and today, the summer solstice — the longest day of the year — is the perfect time to begin embracing it: get children to spend more time outside.

Parents concerned about their children’s spending time playing instead of studying may be relieved to know that the common belief that “near work” — reading or computer use — leads to nearsightedness is incorrect. Among children who spend the same amount of time outside, the amount of near work has no correlation with nearsightedness. Hours spent indoors looking at a screen or book simply means less time spent outside, which is what really matters.

This leads us to a recommendation that may satisfy tiger and soccer moms alike: if your child is going to stick his nose in a book this summer, get him to do it outdoors.

Energy Drinks May Be Harmful To Children

By Nanci Hellmich, USA TODAY

Some young people gulp drinks such as Red Bull, Full Throttle and Rockstar to boost their energy, concentration and athletic performance.

But the caffeinated energy drinks don't appear to provide the purported benefits and can cause problems, including serious medical complications, says a review of the scientific literature published online today in Pediatrics.

The paper is already drawing criticism from the beverage industry, which says energy drinks have no more caffeine than a cup of coffee and aren't widely used by kids and teens.

Steven Lipshultz, chair of pediatrics at the University of Miami School of Medicine, and colleagues reviewed 121 scientific studies, government reports and media sources on energy drinks — different from sports drinks, vitamin waters and sodas.

Energy drinks usually contain 70 to 80 milligrams of caffeine per 8-oz. serving, more than double many cola drinks. Energy drinks also may contain guarana, a plant that contains caffeine, taurine (an amino acid), vitamins, herbal supplements and sweeteners.

Surveys show that 30% to 50% of teens and young adults consume energy drinks, but "we didn't see evidence that drinks have beneficial effects in improving energy, weight loss, stamina, athletic performance and concentration," Lipshultz says.

And the research shows that children and teens — especially those with cardiovascular, renal or liver disease, seizures, diabetes, mood and behavior disorders and hyperthyroidism — are at a higher risk for health complications from these drinks, says Lipshultz, a pediatric cardiologist.

He encourages pediatricians and parents to talk to kids and teens about whether they should be drinking such beverages.

Maureen Storey of the American Beverage Association, an industry group, said in a statement that "this literature review does nothing more than perpetuate misinformation about energy drinks, their ingredients and the regulatory process."

She says government data indicate that the "caffeine consumed from energy drinks for those under the age of 18 is less than the caffeine derived from all other sources including soft drinks, coffee and teas."

Red Bull said in a statement that the study "largely ignores in its conclusions the genuine, scientifically rigorous examination of energy drinks by reputable national authorities. ... The effects of caffeine are well-known, and as an 8.4-oz. can of Red Bull contains about the same amount of caffeine as a cup of coffee (80 milligrams), it should be treated accordingly."

Low Vitamin D Linked to Allergy Risk in Kids

Study Shows Greater Risk of Allergies for Kids and Adolescents Who Don’t Get Enough Vitamin D

By Bill Hendrick
WebMD Health News

Feb. 25, 2011 -- Children who don’t get enough vitamin D may be at increased risk of developing allergies, new research indicates.

Researchers in New York examined serum vitamin D levels in the blood of more than 3,100 children and adolescents and 3,400 adults.

No association was found between low vitamin D levels and allergies in adults, but the link was significant in children and adolescents.

Children and adolescents aged 1 to 21 with low vitamin D levels were at increased risk of having sensitivities to 11 of 17 allergens tested, including environmental andfood allergies.

For example, children who had vitamin D deficiency, which was defined as less than 15 nanograms of vitamin D per milliliter of blood, were 2.4 times more likely to have a peanut allergy than kids with sufficient levels, or 30 nanograms of vitamin D per milliliter of blood.

Children with low vitamin D levels also had increased risk of allergic sensitization to shrimp, dogs, cockroaches, ragweed, oak, ryegrass, Bermuda grass, and thistle.

Avoiding Vitamin D Deficiency

The data came from the National Health and Nutrition Examination Survey 2005-2006 (NHANES), which is a program of studies aimed at assessing the health and nutritional status of adults and children in the U.S.

The study participants underwent blood tests measuring levels of Immunoglobulin E(IgE), a protein that is produced when the immune system responds to allergens.

Researchers say their findings don’t prove that insufficient vitamin D causes allergies in children and adolescents, but strongly suggests that young people should get adequate amounts of the vitamin.

“The latest dietary recommendations calling for children to take in 600 IU of vitamin D daily should keep them from becoming vitamin D deficient,” researcher Michal Melamed, MD, MHS, of the Albert Einstein College Medicine of Yeshiva University, says in a news release.

The study says vitamin D is thought to have anti-inflammatory effects in the body.

The researchers note that the prevalence of vitamin D deficiency is increasing in the U.S., and so is the prevalence of food allergies.

The study is published in the Feb. 17 online edition of the Journal of Allergy and Clinical Immunology.