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why doesnt sungazing burn your retina?
#1
if you focus sunlight into a smallest point on your skin with a burning glass, your skin actually burns
but howcome gazing the sun is safe when the eye lens do the exact same thing on the small point of the retina?
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#2
I've been wondering about this too. why dont we get cancer from the UV like our skin does?
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#3
No, it isn't the same thing as using a magnifying glass to focus the rays. If it were, when you look at the sun you would see only a tiny point of light instead of a larger circle.

It doesn't burn the retina for the same reason that standing in the sun for a short time doesn't give you a sunburn.

Dave
Site Administrator

"Half of our funny, heathen lives, we are bent double to gather things we have tossed away." - George Meredith
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#4
Otter Wrote:I've been wondering about this too. why dont we get cancer from the UV like our skin does?
i think it has to do with the material of the eye. its a diffrent kind of tissue. uv gives skin cancer but have you ever heard of it giving lung cancer,its the same way you cant suntan your palms
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#5
Subject: What Bates said.
At one pont, he suggested looking at the sun directly. There was such a storm of protest, that he stopped suggesting that idea.
Alex Eulenberg did the research on this issue. This is virtually the only issue were a "risk" might be involved as Alex stated.
I have looked at the sun for some time. PROVIDED it is not an eclipse of the sun, the iris somply "shuts down" blocking almost all of the sun's intensity. So very little "power" gets through to the retina.
But futher, when the sun is low on the horizon, and we look at the horizon, the image of the sun is in fact on the retina. Our eyes don't "burn" under that condition. So in our lives we do look at the sun -- but not directly at the sun. This is the only area that Alex suggested "caution" -- as I do.
Best,
Otis
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#6
goohsm Wrote:if you focus sunlight into a smallest point on your skin with a burning glass, your skin actually burns
but howcome gazing the sun is safe when the eye lens do the exact same thing on the small point of the retina?

It is not safe and sungazing does burn your retina. A few seconds of staring at the sun will destroy a small part of the retina and cause permanent reduction of vision. It is called solar retinopathy. The UV light can also cause cancer of the eyelids, cataract, macular degeneration and contributes to various lumps and bumps on the conjunctiva, sclera and cornea.

Don't sungaze and do wear sunglasses when outdoors.

<!-- m --><a class="postlink" href="http://www.epa.gov/sunwise/doc/eyedamage.pdf">http://www.epa.gov/sunwise/doc/eyedamage.pdf</a><!-- m -->

<!-- m --><a class="postlink" href="http://asia.transitions.com/NR/rdonlyres/50F14912-1459-4FE9-9669-CB501CB48DFB/0/children_UV_protect_lichtenstein.pdf">http://asia.transitions.com/NR/rdonlyre ... nstein.pdf</a><!-- m -->

Judy, optometrist
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#7
Judyb Wrote:It is not safe and sungazing does burn your retina. A few seconds of staring at the sun will destroy a small part of the retina and cause permanent reduction of vision. It is called solar retinopathy. The UV light can also cause cancer of the eyelids, cataract, macular degeneration and contributes to various lumps and bumps on the conjunctiva, sclera and cornea.

What Judy said, essentially. I'm very disturbed by the idea of people risking their eyesight by looking directly at the sun--and encouraging others to do the same. While the occasional, accidental glance at the sun won't hurt you, gazing at the sun for seconds at a time WILL burn your retina, it WILL damage your eyesight, and you WON'T recover. And yes, your eyes can become cancerous or otherwise damaged by UV just like your skin.

People claiming to stare at the sun and to have had their eyesight improved by this, instead of irreperably damaged, are one of the reasons I had such a hard time accepting natural methods of eyesight improvement in the first place. More reasonable versions of sunning (involving closed eyes, reasonable precautions against UV damage, or fainter light sources) are credible and probably useful; however anyone claiming to spend significant amounts of time (more than a fraction of a second) gazing directly at the sun is either overestimating the time spent or actively lying about their practices. Why, I don't know; perhaps for effect, perhaps for self-aggrandisment, perhaps for material gain (book sales etc). Whatever the reason, such a person is not to be relied upon as a source of legitimate information.
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#8
The problem here is the same problem with the various parts of the Bates method - Pretty much everything you think you know suggests that it doesn't work, is harmful, is wrong, etc. Eye doctors examine people who have hurt themselves staring at the sun, leading them to conclude that it's always dangerous for everybody. Doctors treat people who have fallen down stairs, which by the same logic would indicate that stairs are dangerous and need to be abolished. They don't treat the people who have walked down stairs successfully, because those people don't seek their attention. Whether you like it or not, me and many others have sungazed without cancer or permanent blind spots, while others do harm themselves long-term by doing so. It's an intense energy and not to be taken lightly. You can hurt youself doing just about anything, but that doesn't mean that everything is dangerous.

But ultimately it's your decision, and it isn't necessary to sungaze to recover your vision.

Dave
Site Administrator

"Half of our funny, heathen lives, we are bent double to gather things we have tossed away." - George Meredith
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#9
Thanks, David! Once again, very illuminating (no pun intended).

So, as I understand it, we're basically talking about a matter of degree; ie that some (careful, controlled, limited) exposure to the light of the sun might be of benefit, whereas gazing directly on the sun with the naked eye is recognised as dangerous?

In my reading of Bates (and I freely admit I may have missed something), I didn't see anything that gave me the impression he recommended any practices that were likely to cause solar retinopathy.

However I have come across material elsewhere online, purporting to be based on Bates' work, which was either so poorly written as to accidentally suggest that looking directly at the sun with the naked eye was a part of Bates' programme, or clearly-written work making outlandish claims about the author's ability to gaze into the sun without harm.

I think one potential confusion here is the understanding that natural sunlight is beneficial to vision--and, in the case of young, developing eyes, absolutely necessary. It's a matter of plain common sense that a person who gets insufficient natural light but must rely on artifical light is going to suffer visual problems sooner or later.

If confined indoors, the light may be sufficiently bright but all the focal distances to which the eye is exposed will be short--it will have no opportunity for distance vision. Outside at night, there's more opportunity for long focal distances--but insufficient light levels. In adults, this will cause a deterioration in eyesight. In the very young, it can be utterly disasterous; such children will end up with appalling vision, perhaps almost blind. In cases where children have been imprisoned by abusive parents, damage to their eyesight is universally remarked upon.

But there is a great difference between reasonable exposure to healthy, natural light levels in the course of outdoor recreation, and overexposure of the sensitive eye tissues to dangerous levels of bright visible light and UV.

Have I got it about right there?
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#10
Incidentally, the reason I am going on about this rather is because that where the Sun is concerned there exists a grave risk of real, disabling, irreversible damage to the eyesight--damage occuring in only seconds, almost before the sufferer is aware that anything was wrong.

A further note, prompted by a mention of solar eclipses upthread: there is nothing special about the light of the sun during an eclipse that makes it more dangerous than at other times. People suffer more eye damage during eclipses purely because they are more inclined to stare at the sun than at other times.

During the 1999 solar eclipse, people in my part of the world were warned in the strongest terms and in all manner of media not to stare at the sun, with safe alternatives being freely suggested and offered. People still went blind. One young woman, only 24, who lost the better part of her vision during the eclipse stated that she'd been well aware of the warnings but thought it was a "health scare." Now she will never enjoy normal sight again. I just don't want to read about something simlar happening to any of our number, that's all.
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#11
In Bates's book he doesn't actually recommend anyone sungaze. He just points out some interesting cases to make a point.

I read a book by Alfred Scholz, MD, who by accident found that radiated light and/or heat from a copper reflector cured his inflammation of the iris and cornea after everything else he tried over a couple months didn't help. I'm not sure it's clear whether it was specifically infrared (far infrared?) rays that did it, or what.

Here's the way I see it. When I do things that have an element of danger, I don't just go for it. I find a way to work towards something by small steps so that any risk is negligible but I still make progress. So with that in mind I wouldn't start out by gazing at the nnonday sun for as long as I can in the middle of summer. Just a few seconds won't cause anything more severe than a harmless temporary blind spot (lasting a few seconds or minutes) caused by a chemical reaction of retinal cells to bright light. I don't know about glasses though, and I've been curious how many of the people sent to hospitals with corneal burns had poor vision and/or were wearing glasses at the time. Someone with poor vision is going to be straining when looking at the sun, so instead of more sacccadic eye movements the eyes will be locked into a stare, even if he does conscious shifting (which doesn't replace the more rapid saccadic movement). And minus lenses shrink images, causing the light rays to be condensed over a smaller area.

Dave
Site Administrator

"Half of our funny, heathen lives, we are bent double to gather things we have tossed away." - George Meredith
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#12
David Wrote:And minus lenses shrink images, causing the light rays to be condensed over a smaller area.Dave

The retinal image size is very similar in myopes wearing minus lenses and in non myopes not wearing minus; the use of a minus lens does not shrink or condense the light.

Judy
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#13
I had uncomfortable experiences with over-exposure to the sun a few times before I got glasses, and afterwards in situations where I had removed my glasses. For example, while spending a day at the beach I generally take off my glasses to go swimming (if the dratted things fall off in the sea, you'll never get them back).

When I lived in Spain, I basically gave myself sunburn of the eyes a few times during protracted dips in the Med. or open-air swimming pools. The combination of bright sun both overhead and reflecting off the water is a dangerous one. No lasting harm was done; however, the lingering hot-sand sensation of sunburned eyes quickly taught me to take better care.
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#14
When I wore strong contacts all lights seemed way too bright & glaring. My eye doctor told me then this is usual for people wearing contacts. Also, think of kids burning up an ant by concentrating the sun's rays with a magnifying glass. Minus eyeglasses also seem to concentrate the light to me (bombarding the macula with concentrated light & "starving" the rest of the retina, as Peter Grunwald puts it). So all of this means to me it is probably a bad idea to look at strong sunlight through prescription lenses. However I am not an eye doctor.
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#15
Nancy Wrote:When I wore strong contacts all lights seemed way too bright & glaring. My eye doctor told me then this is usual for people wearing contacts. Also, think of kids burning up an ant by concentrating the sun's rays with a magnifying glass. Minus eyeglasses also seem to concentrate the light to me (bombarding the macula with concentrated light & "starving" the rest of the retina, as Peter Grunwald puts it). So all of this means to me it is probably a bad idea to look at strong sunlight through prescription lenses. However I am not an eye doctor.

I am an eye doctor. If contacts are not fitting well they can irritate the cornea and cause light sensitivity. Compared to glasses, contacts transmit more light, glasses absorb 5% to 8% of light. A magnifying glass is a plus lens, not a minus lens. If you tried to use a minus lens to burn an ant, it wouldn't work, it would diffuse the light and spread it out. I have no idea what Peter Grunwald means by saying minus lenses starve the retina; minus lenses provide light to all parts fo the retina.

It's a bad idea to look at the sun through strong lenses, weak lenses, plus lenses, minus lenses, contact lenses or with no lenses. It's a bad idea, period.

Judy
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