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wd40
2012-Dec-05, 06:50 PM
I have heard of snow-blindness, but is a "sunburnt eye" causing blindness at coastal level for a healthy male usual as with this CNN reporter?
http://omg.yahoo.com/news/video-anderson-cooper-goes-temporarily-blind-223000961.html

Just what sought of % change in solar emission could endanger human vision?

The film "Day of the Triffids" depicted most of humanity being blinded by a night-time shooting star display. Is there any astronomical event at all that could theoretically blind humanity, temporarily or permanently?

Durakken
2012-Dec-05, 07:34 PM
That sounds wrong from what he is saying...
Overcast day
2 hours
eyes being "sunburnt"
no...

either he has incredibly weak eyes, he's lying, or he's misinterpreting what the doctors said... or the doctor is an idiot as quite a few are... or it's possible that they call it that but it's not actually the same thing.

kpatz
2012-Dec-05, 07:36 PM
Staring at the sun will damage your retinas, as most people know, and it's generally easy to avoid doing this, simply because during usual activities you aren't staring up into the sky at the sun. But water and snow reflect sunlight, and this is harder to avoid "looking" at during normal activity, so this is why retina burn usually happens on water or snow. Ever been skiing or on the beach, and everything is so bright your eyes hurt?

As for an astronomical event, a nearby supernova explosion is the only thing I can think of that would be bright enough to cause any sort of blindness. Chances are if it's close enough to cause blindness it's going to be the least of your worries, as other forms of invisible radiation such as gamma rays will cause bigger problems.

Solfe
2012-Dec-05, 07:37 PM
Maybe he looked at the sun with binoculars. I can't see a camera doing that with all of the electronics between the lens and eye.

Strange
2012-Dec-05, 07:56 PM
I have known people get sunburned eyes when out on the sea. If it is only slightly overcast (not like, "it's about to rain" overcast) it doesn't give much protection from UV. I wonder if he has blue eyes, that can make it worse. And presumably some people are just more sensitive.

ETA: It may be that being slightly overcast could make it worse as the pupils might not dilate as much even though the level of UV is still high.

Torsten
2012-Dec-05, 11:16 PM
The film "Day of the Triffids" depicted most of humanity being blinded by a night-time shooting star display.

I didn't see the film, but in the book, the display that blinded everyone was alleged to be a meteor storm, as the Earth supposedly passed through the debris from a comet (think of the great Leonid storms), but the protagonist has ideas on which he won't elaborate, except to say:

"And yet, until the thing actually began, nobody had ever heard a word about this supposed comet, or its debris..."

I think it's generally understood that the author, John Wyndham, is hinting at the weaponization of space.

Cougar
2012-Dec-06, 01:30 AM
I have heard of snow-blindness, but is a "sunburnt eye" causing blindness at coastal level for a healthy male usual as with this CNN reporter?

No, it's not usual, because most healthy males along the coast have enough sense to wear sunglasses. :cool:

Apparently it's essentially the same as snow blindness.


According to the university [of Houston], symptoms of eye sunburn are blurred vision, irritation, pain, redness, tearing and temporary vision loss (called photokeratitis, or snow blindness). - news article (http://healthyliving.blog.ocregister.com/2010/07/03/did-you-know-eyes-can-get-sunburned/21293/)

grant hutchison
2012-Dec-06, 01:36 AM
I have heard of snow-blindness, but is a "sunburnt eye" causing blindness at coastal level for a healthy male usual as with this CNN reporter?
http://omg.yahoo.com/news/video-anderson-cooper-goes-temporarily-blind-223000961.htmlIt's pretty common if you don't wear UV-filtering sunglasses. It's called solar keratitis, and it's exactly the same thing as snow-blindness. The doctors in seaside resorts get used to seeing it in the summer months.


Just what sought of % change in solar emission could endanger human vision?It already endangers human vision.


The film "Day of the Triffids" depicted most of humanity being blinded by a night-time shooting star display. Is there any astronomical event at all that could theoretically blind humanity, temporarily or permanently?The sun. We've managed to avoid mass blinding so far, though.




Overcast dayAn 80-90% cover of cumulus actually increases the level of UV-B at ground level. It penetrates the cloud well and is then scattered in all directions. So your direct exposure goes down, but your diffuse exposure goes up. That means scattered UV-B is coming at you from all directions, so your eyes are never "in the shade". All that scattering also increases the amount of UV coming back at you off the sea, because there are always lots of glancing rays even when the sun is high. And the ambient shade from visible sunlight means you're more likely to remove your sunglasses. So cloud cover is potentially a ... um ... quadruple whammy.


2 hoursOn the sea. We don't know how long he was on the beach, or the pier, or just generally wandering around without eye protection.




I wonder if he has blue eyes, that can make it worse.Shouldn't do, since the coloured iris is inside the cornea, and it's the cornea that takes the burn. Blue eyes are a risk factor for UV injuries inside the eye, though - cataracts, macular degeneration.


ETA: It may be that being slightly overcast could make it worse as the pupils might not dilate as much even though the level of UV is still high.Again, the size of your pupil doesn't influence the risk of corneal burn, but a big pupil will let more UV into your eye to do the other nasties inside. Which is why you should make sure your sunglasses filter UV as well as visible.

Grant Hutchison

Strange
2012-Dec-06, 01:41 AM
Thanks for that, Grant. I had always naively assumed that it was the retina that got burnt. Duh!

Trebuchet
2012-Dec-06, 01:43 AM
An 80-90% cover of cumulus actually increases the level of UV-B at ground level. It penetrates the cloud well and is then scattered in all directions.

The worst sunburn I ever had, probably second-degree, happened on a cold, overcast day at the beach. Long pants, long sleeves, jacket, hat...and bare feet. I sunburned the tops of my feet horribly.

publius
2012-Dec-06, 04:23 AM
Arc welding without eye protection, and arc flash in general can do the same thing. Exposed skin will even get a sunburn, and the UV can be more intense than sunlight if you're very close.

I did that to my arms a few years ago when I was doing some near continous welding for a large project I was fooling with. It was so hot that day I couldn't stand to wear anything heavy with sleeves and so, like a nut (and knowing the danger) I welded in my T-shirt. It was so hot that it was better to get the hot spatter occasionally on bare skin rather than burn up. The next day, I had a nasty sunburn on my foreams, one spot that was particularly close to the arc being a doozy.

I've been flashed many times as well, both from welding and a more little whoopsies doing electrical work than I'd care to admit, and I have indeed experienced mild symptoms of arc flash eye burns.

Durakken
2012-Dec-06, 04:48 AM
@grant
thanks. Didn't know that...

Don't know how that will help me though. i've stared directly at the sun for long periods relative to how long other have stared at the sun... which might explain why my eyes are 20/200 ^.^

Ara Pacis
2012-Dec-06, 05:54 AM
As for an astronomical event, a nearby supernova explosion is the only thing I can think of that would be bright enough to cause any sort of blindness. Chances are if it's close enough to cause blindness it's going to be the least of your worries, as other forms of invisible radiation such as gamma rays will cause bigger problems.

Gammas won't make it through the atmosphere. Also a GRB or meteor shower will only affect one side of the Earth. The other side would be shielded by the mass of the planet.

grant hutchison
2012-Dec-06, 12:45 PM
The worst sunburn I ever had, probably second-degree, happened on a cold, overcast day at the beach. Long pants, long sleeves, jacket, hat...and bare feet. I sunburned the tops of my feet horribly.Here (http://www.ghutchison.pwp.blueyonder.co.uk/Dsc00008.jpg) (360KB jpg) is a good example of the problem.
Rubbish picture (taken with my GPS receiver), at an altitude of about 1100m in the Scottish Highlands on a May afternoon. I think most people would agree that the sky qualifies as "overcast", although glimpses of blue were visible intermittently. I was walking on snow for about an hour and a half out of a total trip lasting seven hours. No sunglasses with me, and I was aware of a distinct dazzle sensation from the snow, despite what felt like rather low-intensity sunlight.
By evening, I had intensely gritty-feeling eyes and slightly blurred vision, which settled overnight - a mild corneal burn, to match my burnt nose and a little patch of sunburn under my chin. That's spring, in Scotland.

Grant Hutchison

NEOWatcher
2012-Dec-06, 08:59 PM
I wonder if he has blue eyes, that can make it worse.
Oh so close. Not blue eyes, but maybe blue jeans.
Anderson Cooper: I never wash my jeans (http://todayentertainment.today.com/_news/2012/12/06/15731802-anderson-cooper-i-never-wash-my-jeans?lite)
I know dirty clothes tend to irritate my eyes.

wd40
2012-Dec-09, 09:48 PM
Can the radiation from a solar flare or during a Carrington Event increase the risk of eye burn?

If CFCs use had continued apace and had not been banned in the 80s and the Ozone Layer had been eroded, would we have been experiencing more eye burns by today, or was it a depletion process that would have taken centuries before real occular damage resulted?

publius
2012-Dec-10, 09:07 AM
By evening, I had intensely gritty-feeling eyes and slightly blurred vision, which settled overnight - a mild corneal burn, to match my burnt nose and a little patch of sunburn under my chin. That's spring, in Scotland.

Grant Hutchison

Glad to see you here again.

Yep, "sand in the eyes" is what it feels like. As I mentioned above, I got my little experience with that from arc welding. Turns out it was *reflected* light that did it, something I wasn't even thinking about. I did it with my MIG machine right after I'd got it, and it seems to make a bit more of intense arc. I'm trying to remember, but there was something in my shop that turned out to be the reflecting culprit, and I just happened to be working at the wrong place relative to that. But anyway, it reflected enough into the back of the helmet over time to do some mild damage.

Anyway, after that, I'm far more careful about making sure nothing is going to reflect too much.