In Eyes, a Clock Calibrated by Wavelengths of Light

By LAURA BEIL

Published: July 4, 2011

New York Times

Just as the ear has two purposes — hearing and telling you which way is up — so does the eye. It receives the input necessary for vision, but the retina also houses a network of sensors that detect the rise and fall of daylight. With light, the body sets its internal clock to a 24-hour cycle regulating an estimated 10 percent of our genes.

The workhorse of this system is the light-sensitive hormone melatonin, which is produced by the body every evening and during the night. Melatonin promotes sleep and alerts a variety of biological processes to the approximate hour of the day.

Light hitting the retina suppresses the production of melatonin — and there lies the rub. In this modern world, our eyes are flooded with light well after dusk, contrary to our evolutionary programming. Scientists are just beginning to understand the potential health consequences. The disruption of circadian cycles may not just be shortchanging our sleep, they have found, but also contributing to a host of diseases.

“Light works as if it’s a drug, except it’s not a drug at all,” said George Brainard, a neurologist at Thomas Jefferson University in Philadelphia and one of the first researchers to study light’s effects on the body’s hormones and circadian rhythms.

Any sort of light can suppress melatonin, but recent experiments have raised novel questions about one type in particular: the blue wavelengths produced by many kinds of energy-efficient light bulbs and electronic gadgets.

Dr. Brainard and other researchers have found that light composed of blue wavelengths slows the release of melatonin with particular effectiveness. Until recently, though, few studies had directly examined how blue-emitting electronics might affect the brain.

So scientists at the University of Basel in Switzerland tried a simple experiment: They asked 13 men to sit before a computer each evening for two weeks before going to bed.

During one week, for five hours every night, the volunteers sat before an old-style fluorescent monitor emitting light composed of several colors from the visible spectrum, though very little blue. Another week, the men sat at screens backlighted by light-emitting diodes, or LEDs. This screen was twice as blue.

“To our surprise, we saw huge differences,” said Christian Cajochen, who heads the Center for Chronobiology at the University of Basel. Melatonin levels in volunteers watching the LED screens took longer to rise at night, compared with when the participants were watching the fluorescent screens, and the deficit persisted throughout the evening.

The subjects also scored higher on tests of memory and cognition after exposure to blue light, Dr. Cajochen and his team reported in the May issue of The Journal of Applied Physiology. While men were able to recall pairs of words flashed across the fluorescent screen about half the time, some scores rose to almost 70 percent when they stared at the LED monitors.

The finding adds to a series of others suggesting, though certainly not proving, that exposure to blue light may keep us more awake and alert, partly by suppressing production of melatonin. An LED screen bright enough and big enough “could be giving you an alert stimulus at a time that will frustrate your body’s ability to go to sleep later,” said Dr. Brainard. “When you turn it off, it doesn’t mean that instantly the alerting effects go away. There’s an underlying biology that’s stimulated.”

Still, nobody is suggesting that we all turn off the lights at dusk and sit in the dark; research into this area is in its infancy. “We are only beginning to understand what really happens under natural conditions,” said Mark Rea of the Lighting Research Center at Rensselaer Polytechnic Institute in New York.

Artificial light has been around for more than 120 years. But the light emitted by older sources, like incandescent bulbs, contains more red wavelengths. The problem now, Dr. Brainard and other researchers fear, is that our world is increasingly illuminated in blue. By one estimate, 1.6 billion new computers, televisions and cellphones were sold last year alone, and incandescent lights are being replaced by more energy-efficient, and often bluer, bulbs.

In January in the journal PLoS One, the University of Basel team also compared the effects of incandescent bulbs to fluorescents modified to emit more blue light. Men exposed to the fluorescent lights produced 40 percent less melatonin than when they were exposed to incandescent bulbs, and they reported feeling more awake an hour after the lights went off.

In addition, the quantity of light necessary to affect melatonin may be much smaller than once thought. In research published in March in The Journal of Clinical Endocrinology and Metabolism, a team at the Harvard Medical School reported that ordinary indoor lighting before bedtime suppressed melatonin in the brain, even delaying production of the hormone for 90 minutes after the lights were off, compared with people exposed to only dim light.

What do these findings mean to everyday life? Some experts believe that any kind of light too late into the evening could have broad health effects, independent of any effect on sleep. For example, a report published last year in the journal PNAS found that mice exposed to light at night gained more weight than those housed in normal light, even though both groups consumed the same number of calories.

Light at night has been examined as a contributor to breast cancer for two decades. While there is still no consensus, enough laboratory and epidemiological studies have supported the idea that in 2007, the World Health Organization declared shift work a probable carcinogen. Body clock disruptions “can alter sleep-activity patterns, suppress melatonin production and disregulate genes involved in tumor development,” the agency concluded.

Blue light’s effects might be particularly pronounced for shift workers and others who get little natural daylight, some researchers say. Consider one small trial that appears the June issue of The Journal of the American Medical Directors Association. Among 28 elderly nursing home residents, those exposed to just 30 minutes of blue light on weekdays for four weeks showed improvement in cognitive abilities, compared with patients exposed only to red.

Researchers like Dr. Brainard hope the science may lead to a new generation of lights and screens designed with wavelengths that adjust according to the hour of the day.

Among those interested are officials at NASA, who have approached the neurologist about designing light on the International Space Station in a way that promotes alertness during waking hours and encourages sleep during times of rest.

“I think we’re on the verge of a lighting revolution,” said Dr. Brainard. If the hormone-sparing lights can be made to work during spaceflight, he said, “people will use it here on the ground.”

Buying 'cheap' sunglasses can be hazardous to your health.

Seizure of 560,000 pairs of unsafe sunglasses
01-07-2011

Allegedly hazardous eyewear made in China was confiscated in Venice
As part of an operation that involved numerous provinces in Italy, the Venice Guardia di Finanza (Italian tax police) seized about 560,000 pairs of sunglasses made in China and valued at 10 million Euro: the lenses were considered to be an extreme health hazard.
The operation was triggered by a display of eyeglasses in a Venice store with price tags that were well below market prices: a subsequent check of the goods revealed that the labels and CE markings had been illegally applied.
Technical analyses of the material demonstrated that in addition to not having UV filters, the lenses also released nickel on contact with perspiration. Also seized were 3.2 million labels that would have been applied to products imported from China to Italy.

Nickel can cause nasty rashes and allergic reactions if it comes into contact with skin and nickel dust is a carcinogen if inhaled. Sunglasses that do not have proper UV protection actually expose you to higher levels of UV light since your pupils remain dilated behind the sunglass lens and allow even more light and UV rays to enter the eye. Excessive exposure to UV can lead to earlier development of cataracts and macular degeneration.
The seven Chinese and Italian importers involved paid less than ten Eurocents a pair for the seized eyewear, which was placed on the market at prices ranging from 8 to 15 Euro.

Giant Weed Can Cause Blisters, Even Blindness

Officials urge people to steer clear of the giant hogweed

Note**** This is a US post, but this weed IS present in Nova Scotia and the Halifax area... beware!!

THURSDAY, July 7 (HealthDay News) -- Call it the import that nobody wants.

Experts are urging residents of several states to beware of the "giant hogweed," a tall plant native to Central Asia with umbrella-size flowers containing toxic sap that can cause burns, blisters and, in some cases, even blindness.

"Avoid it at all cost," Jodi Holt, a professor of plant physiology at University of California, Riverside, toldABC News.

"The sap causes something called phytophotodermatitis when it touches humans," causing scars and potentially blindness if it comes into contact with the eyes, Holt said. Some cases of blindness occurred after children used the hollow stalks as telescopes.

Heracleum Mantegazzianum, as hogweed is botanically known, is already a concern in the Northeast and spreading fast. Patches of giant hogweed have also been sighted in the Pacific Northwest.

With white blossoms a foot or larger in diameter, giant hogweed towers up to 15 feet tall and thrives in wet, cool places. It is often spotted near homes, roadways, railroad beds and streams, ABC News said.

Crews in several states, including New York, have been charged with seeking out and destroying the invasive species. New York has also set up a giant hogweed hotline -- 845-256-3111-- for people to identify sightings.

Typically, large quantities of herbicides are needed to vanquish the plant when found in large patches. Smaller patches can be controlled by hand-cutting the roots, according to published reports.

Giant hogweed has been found and destroyed in three counties of Vermont -- Bennington, Washington and Windsor, state plant pathologists reported. And officials in Washington, D.C., are asking residents to be on the lookout for giant hogweed so they can weed out the botanical terrorist, according to news reports.

According to the New York state Department of Environmental Conservation, reactions can occur within 15 minutes when skin contact occurs in conjunction with sunlight. The sap contains a photosensitizing chemical that accelerates sun damage and can result in a serious sunburn. Perspiration can increase the reaction, officials said.

If you spot giant hogweed, don't try to remove it yourself, experts said. Instead, report the sighting to your state or local department of invasive species control.

"The importance of learning what the plant looks like cannot be overstated," Holt told ABC News.

The U.S. Department of Agriculture has put the giant hogweed near the top of its Federal Noxious Weed list. The agency said the plant has been reported in Connecticut, Maine, Maryland, Massachusetts, Michigan, New York, New Hampshire, Ohio, Oregon, Pennsylvania, Washington and Vermont.

More information

To learn more about poisonous plants, visit the U.S. Food and Drug Administration.

-- HealthDay staff

SOURCES: New York state Department of Environmental Conservation; ABC News

Last Updated: July 07, 2011

Copyright © 2011 HealthDay. All rights reserved.

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.

Fog Has Lifted for Spectacle Wearers

Researchers in Canada have developed the first permanent anti-fog coating, according to a study in the March issue of Applied Materials and Interfaces. They suggest that this development could be used indefinitely to eliminate the buildup of fog on eyeglasses, windshields, goggles and camera lenses.

Researchers at Laval University in Quebec City applied a polyvinyl alcohol compound to a series of glass surfaces. The polyvinyl alcohol coating allowed moisture to spread more uniformly across a glass surface instead of forming dispersed vapor droplets. To promote better surface adhesion, the researchers applied four successive layers of molecules, which also enhanced the coating’s durability.

The final result was a thin, transparent, anti-fog coating that did not alter the optical properties of the surface on which it was overlaid. And best of all, the specialized coating did not wash off even after 24 hours of water immersion.

“Existing anti-fog treatments don’t have these properties and won’t withstand washing, so the product application must be repeated regularly,” says lead author Gaetan Laroche, Ph.D., professor of sciences and engineering at Laval. “Our coating, on the other hand, is permanent.”

Negotiations are currently underway with a major eyewear company that is interested in obtaining a license for this technology.

Chevallier P, Turgeon S, Sarra-Bournet C, et al. Characterization of multilayer anti-fog coatings. ACS Appl Mater Interfaces. 2011 Mar;3(3):750-8.

Consuming more olive oil may protect against strokes

By Jeannine Stein, Los Angeles Times / For the Booster Shots blog

June 15, 2011, 1:55 p.m.

Pour some more of that EVOO on your plate -- a study finds that eating more olive oil could be linked with lower stroke risk in older people.

Medical records of 7,625 people 65 and older who lived in three French cities were examined by researchers to determine how their olive oil consumption affected their chances of having a stroke. The participants had no history of stroke at the beginning of the study.

Olive oil is a component of the Mediterranean diet, which is rich in healthy fats (like olive oil and nuts), plus whole grains, fruits, vegetables, fish and chicken. Red meat and wine are consumed in moderate amounts, and regular physical activity is part of the regimen as well. Other studies have linked the Mediterranean diet with a lower risk of heart disease, but scientists are still assessing the roles various portions of the diet and lifestyle play.

In this study, participants were surveyed about how much olive oil they consumed: About 23% used none, 40% were moderate users (cooking with it or using it as a dressing or with bread) and about 37% were intensive users (using it in cooking and as a dressing or with bread).

In an average 5.25 years of follow-up, 148 strokes occurred. Those who were intensive users had a 41% lower stroke risk compared to those who never used olive oil. Researchers arrived at that number after adjusting for such factors as body mass index, other stroke risk factors, diet and physical activity. The results were statistically significant for ischemic stroke (caused by blockage of an artery to the brain) but not hemorrahagic stroke (caused by the rupture of a blood vessel).

The authors noted that the findings could be used to make dietary recommendations for older people at risk for stroke. The study was published online Wednesday in the journal Neurology.

Scientists make eye's retina from stem cells

By Michelle RobertsHealth reporter, BBC News
A part of the eye that is essential for vision has been created in the laboratory from animal stem cells, offering hope to the blind and partially sighted.

One day it might be possible to make an eye in a dish, Nature journal reports.

The Japanese team used mouse stem cells - immature cells that have the ability to turn into many types of body tissue.

With the right mix of nutrients, the cells changed and began to grow to make a synthetic retina.

Ultimately, scientists hope they can use this approach to make endless supplies of retinal cells or indeed whole retinas that can be transplanted into patients with visual impairment.

Eventually, it may even be possible to create a whole eye.

A US biotech company has already been granted a license to begin human trials of a stem cell treatment for blindness.

'Landmark discovery'

The retina is the name given to a diverse group of cells that line the inside of the back of eye.

Rays of light enter the eye and are focused onto the retina which produces a picture that is then is sent along the optic nerve for the brain to interpret.

The eye and the brain together produce the images that we see.

Retinal diseases can cause severe vision loss or blindness if left untreated.

Retinitis pigmentosa and age-related macular degeneration (AMD) are the most common causes of blindness in old age, and involve the gradual and normally irreversible destruction of retinal cells.

In the Japanese study, the cultured stem cells spontaneously organised themselves into a complex structure that resembled the developing embryonic eye.

The three-dimensional, layered structure was reminiscent of the optic cup, a two-walled pouch-like structure, which ultimately develops into the inner and outer layers of the retina.

The scientists said they were surprised at how well the cells organised themselves with little intervention from them.

They said: "Self-formation of fully stratified 3D neural retina tissues heralds the next generation of generative medicine in retinal degeneration therapeutics, and opens up new avenues for the transplantation of artificial retinal tissue sheets, rather than simple cell grafting."

Professor James Bainbridge of Moorfields Eye Hospital NHS Foundation Trust said: "Generation of a synthetic retina from embryonic stem cells is a landmark discovery that will help enormously our understanding of blinding eye disease.

"It is particularly exciting that this could also provide a source of cells for transplantation."

Barbara McLaughlan of the RNIB charity said: "This piece of research contributes to the ongoing efforts to harness stem cell research to benefit patients with a number of eye diseases.

"We welcome these efforts particularly where they move from early laboratory research in mice to trials in humans that are an essential part of developing safe and effective treatments."