Friday, 18 August 2017

Here’s what happens to your retina if you view an eclipse without protection

quote [ Americans are making their last dashes for glasses and viewers to watch the rare total solar eclipse that will glide across the continental US on Monday. Meanwhile, eye doctors are trying to clear away any orbiting debris that's obscuring vision safety information—and spotlight the dangers of unsafe viewing.

Everyone knows that watching an eclipse—or staring into the Sun in general—can damage eyes. But in a series of articles published Friday in JAMA and JAMA Ophthalmology, a group of ophthalmologists explains in detail how sunlight damages the retina, plus dispels some misconceptions about viewing techniques for the rare event. They also provide a case study of what happens when you go into an eclipse event eyeballs-out. ]

Don't stare at the sun on Monday.

Also (sticking to the space theme here) - SpaceX sends a supercomputer and lots more science experiments to space station.


Sunlight damages the eye in two distinct ways


Exposing your naked eye-ball to sunlight causes solar retinopathy (aka photic retinopathy or solar retinitis), which involves two types of damage to the retina, particularly the fovea: burns and photochemical toxicity.

The former may be the most easily understood. A big chunk of sunlight is near-infrared radiation (700 to 1,500 nanometers), which can cause heat and thus burns, Calkins and Sternberg note. Because our eyes lack pain receptors, we can scorch the fovea without even noticing as we gaze at the Sun.

But, the eye experts write, a "more pressing concern" is photochemical toxicity. The large wallop of visible light from the Sun gets soaked up by photoactive materials in the eye that are just itching to form free radicals and reactive oxygen species. These include heme proteins, melanosomes, lipofuscin, and other chemicals. Once generated, free radicals and reactive oxygen species can attack many types of molecules and break down membranes, leading to tissue damage and cell death. Once retina tissue is destroyed, it cannot regenerate.

The authors say that a study of 45 people who damaged their eyes during a 1999 eclipse in the UK supports the idea that photochemical toxicity is a frequent cause of vision damage in solar retinopathy. In those cases, most of the damage was not permanent. Only four of the 45 reported lingering symptoms—discomfort and vision problems—after seven months.

But, of course, irreversible damage is more likely with longer and larger exposures. A case report published by Ta C. Chang and Kara Cavuoto of the University of Miami’s Bascom Palmer Eye Institute detailed lasting injuries in a 12-year-old girl. She suffered severe vision damage after staring at the full Sun for about one full minute. The eye experts presented images of her damaged retina, one of which was obtained by optical coherence tomography (OCT), which is kind of like an ultrasound for the eye that uses light to create cross-sectional tissue images. The images show bright pitted spots (see white arrows) in her fovea where photoreceptor segments have been wiped out by Sun damage. On follow-up exams, her vision hadn’t gotten better.
[SFW] [science & technology] [+2]
[by knumbknutz@10:29pmGMT]

Comments

midden said[2] @ 10:42pm GMT on 18th Aug [Score:1 Underrated]
"For those in the totality path, the Sun’s core will be blotted out for no more than two minutes and 41 seconds. “However, for most people, at least some portion of the Sun’s core will be visible during the event,” Calkins and Sternberg note."

pedant

Actually, the Sun's core is never visible, only the photosphere, chromosphere and the corona are.

/pedant
Bruceski said @ 5:18am GMT on 19th Aug
Which part is visible during sunspots?
arrowhen said @ 8:44am GMT on 19th Aug
Sunspots are areas of the phostophere with a lower temperature. They're only dark in relation to the rest of the solar surface; if you saw one in isolation it would look brighter than the moon.
donnie said @ 12:57am GMT on 19th Aug [Score:1 laz0r]
This is a load of crap - Breitbart needs to get the news out that this advice is only for lowly and pathetic genetic refuse. The racially pure can naturally view the eclipse without any risk of injury whatsoever. It's a testament to the quality of their genetics.
Ankylosaur said @ 10:59pm GMT on 18th Aug
"Kentuckians for Coal" to Protest the Solar Eclipse August 21!
If you're planning to visit Hopkinsville, Kentucky, to see the total eclipse of the sun on August 21, 2017, be prepared. Hopkinsville (a.k.a. Eclipseville) is globally recognized to be the epicenter of the eclipse. Hundreds of thousands of spectators will converge on the town to see it. Among them "Kentuckians for Coal" will be in the vanguard protesting the eclipse.

Kentuckians for Coal is an ad-hoc coalition of miners, union officials, family members and coal users created to defend the Kentucky coal industry against encroachment from renewable energy industries and from economic development initiatives aimed at lessening America's dependence on coal. Kentuckians for Coal stands against the eclipse and those who worship it.

...

When more than 250,000 people descend on the town for four days in August, including busloads of Amish from Pennsylvania and rumored Arab royalty, hucksters will peddle overpriced souvenirs as area hotels jack up their room rates by 400%; gas stations run out of gas; and cell phone service crashes due to demand. Traffic jams, a run on available food, an invasion of prostitutes, and rowdy crowds will test the patience of both local residents and the extra law enforcement brought in to maintain order. In addition, there is the serious threat to spectators' eyesight if they look at the sun without special eclipse-viewing glasses.

...

Kentuckians for Coal is grateful for the support of our esteemed president Donald J. Trump and the great Kentucky Senator Mitch McConnell.
Bruceski said @ 5:21am GMT on 19th Aug
The epicenter is Madras and Prineville, not Kentucky. Two different huge festivals, and best odds of good weather.
arrowhen said @ 8:34am GMT on 19th Aug
Coaler eclipse.
Hugh E. said @ 11:24pm GMT on 18th Aug
Tuesday you can shoot the moon
Wednesday shoot for the stars
Thursday you can sleep until noon
And Friday look for the men from Mars
(chorus)
Saturday dance in the dark until Sunday
Just don't stare at the sun on Monday
thepublicone said @ 11:49pm GMT on 18th Aug
I wonder what the over/under is on the number of idiots who will either be blinded or have their vision damaged during the eclipse. This is, after all, the country that brought you missing fingers on Independence day and Oil Burns from Garbage Can fryers on Thanksgiving.
HoZay said @ 12:16am GMT on 19th Aug
We're risk takers.
steele said @ 2:22am GMT on 19th Aug
I slept on getting glasses :(
Bruceski said @ 5:22am GMT on 19th Aug
I have two extra as spares. Plan to scalp em day off if we don't need em.

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