Posts Tagged ‘eyeball’

Blue light’s rap sheet is growing ever longer. Researchers have connected the high-energy visible light, which emanates from both the sun and your cell phone (and just about every other digital device in our hands and on our bedside tables), to disruptions in the body’s circadian rhythms. And physicians have drawn attention to the relationship between our favorite devices and eye problems, ranging from everyday eye strain to glaucoma to macular degeneration.

Humans can see a thin spectrum of light, ranging from red to violet. Shorter wavelengths appear blue, while the longer ones appear red. What appears as white light, whether it’s from sunlight or screen time, actually includes almost every color in the spectrum. In a recent paper published in the journal Scientific Reports, researchers at the University of Toledo have begun to parse the process by which close or prolonged exposure to the 445 nanometer shortwave called “blue light” can trigger damage irreversible damage in eye cells. The results could have profound consequences for consumer technology.

“Photoreceptors are like the vehicle. Retinal is the gas,” says study author and chemistry professor Ajith Karunarathne. In the lab, when cells from the eye were exposed to blue light directly—in theory, mimicking what happens when we stare at our phone or computer screens—the high-intensity waves trigger a chemical reaction in the retinal molecules in the eye. The blue light causes the retinal to oxidize, creating “toxic chemical species,” according to Karunarathne. The retinal, energized by this particular band of light, kills the photoreceptor cells, which do not grow back once they are damaged. If retinal is the gas, Karunarathne says, then blue light is a dangerous spark.

Catastrophic damage to your vision is hardly guaranteed. But the experiment shows that blue light can kill photoreceptor cells. Murdering enough of them can lead to macular degeneration, an incurable disease that blurs or even eliminates vision.

Blue light occurs naturally in sunlight, which also contains other forms of visible light and ultraviolet and infrared rays. But, Karunarathne points out, we don’t spend that much time staring at the sun. As kids, most of us were taught it would fry our eyes. Digital devices, however, pose a bigger threat. The average American spends almost 11 hours a day in front of some type of screen, according to a 2016 Nielsen poll. Right now, reading this, you’re probably mainlining blue light.

When we stare straight at our screens—especially in the dark—we channel the light into a very small area inside our eyeball. “That can actually intensify the light emitted from the device many many fold,” Karunarathne says. “When you take a magnifying glass and hold it to the sun, you can see how intense the light at the focal point gets. You can burn something.”

Some user experience designers have been criticizing our reliance on blue light, including Amber Case, author of the book Calm Technology. On her Medium blog she documented the way blue light has become “the color of the future,” thanks in part to films like 1982’s Blade Runner. The environmentally-motivated switch from incandescent light bulbs to high-efficiency (and high-wattage) LED bulbs further pushed us into blue light’s path. But, Case writes, “[i]f pop culture has helped lead us into a blue-lit reality that’s hurting us so much, it can help lead us toward a new design aesthetic bathed in orange.”

The military, she notes, still uses red or orange light for many of its interfaces, including those in control rooms and cockpits. “They’re low-impact colors that are great for nighttime shifts,” she writes. They also eliminate blue light-induced “visual artifacts”—the sensation of being blinded by a bright screen in the dark—that often accompany blue light and can be hazardous in some scenarios.

Apple offers a “night shift” setting on its phones, which allow users to blot out the blue and filter their screens through a sunset hue. Aftermarket products designed to control the influx of blue light into our irises are also available, including desktop screen protectors. There are even blue light-filtering sunglasses marketed to specifically to gamers. But as the damage done by blue light becomes clearer—just as our vision is getting blurrier—consumers may demand bigger changes.

Going forward, Karunarathne plans to stay in data-collection mode. “This is a new trend of looking at our devices,” he says. “It will take some time to see if and how much damage these devices can cause over time. When this new generation gets older, the question is, by that time, is the damage done?” But now that he appears to have identified a biochemical pathway for blue light damage, he’s also looking for new interventions. “Who knows. One day we might be able to develop eye drops, that if you know you are going to be exposed to intense light, you could use some of those… to reduce damage.”

https://www.popsci.com/screens-killing-eyes-blue-light?dom=currents&src=syn#page-3

A student in Taiwan who kept a pair of disposable contact lenses in her eyes for six months has been left blinded after a microscopic bug devoured her eyeballs.

The tiny single-cell amoeba ate away at undergraduate Lian Kao’s sight because she didn’t take out and clean the contacts once during that time.

According to a warning issued by doctors the case was a particularly severe example of a young person under pressure who did not take the time to carry out basic hygiene on their contact lenses

As well as being regularly cleaned, contact lenses should also be removed when swimming and washing.

The general advice is to avoid wearing contacts for more than eight hours a day.

Yet apparently 23-year-old Kao had even kept her contact lenses in at all times, even at the swimming pool.

Medics were horrified when they removed the contact lenses to find that the surface of the girl’s eyes had literally been eaten by the amoeba that had been able to breed in the perfect conditions that existed between the contact lens and the eye.

The director of ophthalmology at Taipei’s Wan Fang Hospital, Wu Jian-liang, said: ‘Contact lens wearers are a high-risk group that can easily be exposed to eye diseases.

‘A shortage of oxygen can destroy the surface of the epithelial tissue, creating tiny wounds into which the bacteria can easily infect, spreading to the rest of the eye and providing a perfect breeding ground.

‘The girl should have thrown the contact lenses away after a month but instead she overused them and has now permanently damaged her corneas.’

He said that she had been diagnosed with acanthamoeba keratitis, which although rare was always more common in the summer.

He confirmed and spoke about the girl’s case as a way of urging others to be more careful if they had to use contact lenses.

The problem is the condition can build up over several years – it’s only when it gets to an advanced stage that contacts wearers become aware of a problem, as that’s when it will cause red, irritated eyes, by which time it may be too late.

Acanthamoeba bugs stick to contact lenses and can then burrow their way through the cornea, causing acute pain.

It’s only at this stage that a sufferer would be aware they had a problem.

Prescription drugs may be able to treat the bug in the early stages, but specialists say it is very difficult to get rid of. In serious cases, the patient needs a corneal transplant but these have a high failure rate, resulting in sight loss.

Other steps to prevent the infection include never swimming or using a hot tub or shower when wearing contacts.

Each year, infections cause around 6,000 cases of a severe eye condition known as microbial keratitis – inflammation and ulceration of the cornea that can lead to vision loss.

Contact lens wearers are at a higher risk, since bacteria can get trapped in the lenses.

Read more: http://www.dailymail.co.uk/news/article-2687477/Student-goes-blind-keeping-contact-lenses-six-months-microscopic-bug-EATS-eyeballs.html#ixzz37dnGxTKv

Thanks to Pete Cuomo for bringing this to the attention of the It’s Interesting community.