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.

Overnight contacts may help slow eyesight deterioration in children.

Our office is pleased to offer CRT (Corneal Refractive Therapy) lenses as mentioned in the followoing article from the UK's Daily Mail. (10/20 Hodgekiss). After fitting the lenses myself for the last 5 years, it has been my experience that there is very little increase in a child's prescription. It is most encouraging to be able to fit children with a contact lens that will halt or slow the progression of myopia!

Contact lenses worn at night could slow down or even halt sight deterioration in children.
The vast majority of children with sight problems are short-sighted — they have difficulty seeing things far away. This is caused by a misshapen eyeball.
The new contact lenses work in a similar way to a dental brace, gently pressing on the eye to restore it to the shape of someone with normal vision.
New research has found that after a year of use, children had far less sight deterioration than those who’d worn regular contact lenses.
In normal sight, the light rays pass into the eye through the cornea. They then hit the retina at the back of the eye where they are transformed into image-forming signals, which are then sent to the brain.
With short-sight, the cornea is either too curved or the eyeball too long. This means the light rays from distant objects focus in front of the retina, rather than directly on it, making the objects appear fuzzy.
The overnight lenses, which have been available for several years to help adults, work by gently pressing on the cornea, reducing its curvature and thereby refocusing the light directly on to the retina. It also, in effect, shortens the eyeball.
The reshaping in adults is temporary because the cornea will gradually spring back to its original shape, so the lenses must be worn every night. (The lenses themselves are slightly harder than the softer lenses people commonly use for daytime wear.)
However, a few years ago scientists noticed that children who wore this type of contact lens had a slower deterioration of their eyesight, — the reshaping seemed to be more permanent.
On this observation, a controlled clinical trial of the lenses was set up in the U.S. two years ago. Around 300 children aged eight to 14 are taking part in the five-year study, known as SMART.
Half of the subjects have been given the overnight lenses, while the others are using normal contact lenses every day. At the end of the first year, both groups stopped wearing their lenses for one month to see if their prescription had changed.
Sight loss is measured in diopters. In children who are short-sighted it is estimated that sight deteriorates by 0.25 to 1.2 diopters a year (as a guide, most adults have a prescription that is no worse than minus 5).
The results showed that, after the first year, the children in the overnight lens group had no prescription change; in the control group the average increase was 0.4 diopters.
Because shortsightedness is usually picked up by the early teenage years, it is hoped overnight lenses could at least prevent further sight deterioration.
The reason why children seem to benefit more than adults is because their eyes are still growing — this makes it easier to change their shape, just as it’s easier to fix misaligned teeth in children rather than adults.
Michael Ward, a 13-year- old from Watford, has been wearing the overnight lenses for two years.
Before then, the keen sportsman had to either wear his glasses when playing sport or not wear them at all.
‘It’s made a huge difference because I can see everything now,’ he says. The rate of his sight deterioration has also slowed. ‘I went river rafting one weekend and didn’t wear them for two nights — my sight only started to get worse on the third day.’
Parwez Hossain, a consultant in ophthalmology at Southampton General Hospital and member of the scientific committee of the Royal College of Ophthalmologists, says these lenses could potentially be a cure for short-sightedness, although ‘we won’t know this for another few years’.