Nuclear Flash Blindness; A surprising result?

A great many of us have heard of the phenomenon of nuclear flash blindness and/or retinal burn. This is the process where the sheer magnitude of light across the spectrum which comes from the first seconds of a nuclear blast overwhelms the optic nerve and retina. This sometimes causes physical retinal burns. Protected vision results in minimal effects, but unprotected can be unpleasant.

In fact, I recall being taught in school during the 80's and having the same reinforced by media, that looking toward a nuclear detonation would cause permenant and total blindness at the worst cases to severe impairment in the best. A number of movies have depicted this very same thing, including a couple movies which greatly impacted a generation.

The Day After

By Dawn's Early Light

Now, how surprised would you be to learn that these lessons were false for projecting the impact of a detonation viewed through unprotected eyes? I'm guessing many simply take it on faith that it's like looking into the sun through binoculars. A certain trip to learning how to move through the world without eye sight. That would be wrong, as I discovered by some research.

It turns out, this isn't something we need guess about. Like so much else, our Government helpfully and knowingly exposed people to just that experience to 'see what would happen'. They learned, too. Now let me share with everyone here just what those lessons were.

I'll take the summary here to give a picture of the lesson garnered from multiple tests.

3.5 SUMMARY OF NUCLEAR BURST EFFECTS ON HUMAN EYES

3.5.1 Flash-Blindness.

- Unprotected, dark-adapted:

The only data available on flashblindness effects on the dark-adapted unprotected human eye are from Operation TUNIBLER-SNAPPER. Those results indicate that viewing from 16 km the fireballs of 30-kt or 18.5-kt low-air bursts for an interval between 46 and 52 sec until blink will require considerable recovery periods and is likely to produce a minimal retinal burn.

- Unprotected, day-adapted:

Results at several tests indicate that light adapted subjects oriented away from line-of-sight of the bursts experienced no visual impairment. Those subjects in aircraft who viewed a 14-kt low-air burst from a distance of about 14.5 km experienced temporarily impaired vision with recovery in 2 min. Other recovery times have been noted as within 5 min.

Source

Those excerpts can be found on pages 26-27 on actual numbering. The report itself was generated in April, 1971 by the Defense Atomic Support Agency.

For those with math far higher than mine, the pages following the range quoted above go into the equations and math which make sense of the results observed in actual witnesses of live nuclear detonations. Simulations were also used to extrapolate data and determine safe min. distances for a range of sizes up to 1,000 Kiloton airburst weapons. Again, the science and math is about 10 years into engineering beyond where I ever plan to go. That's why I selected the paragraphs I did.

Pages preceding the quoted ones go into the lay details of the shot series that the witnesses were in and live testing of unprotected eyes was terminated following the physical injury of two people. One of which, the report is thought to describe (It's presumption and noted as such), while the other is never detailed for what happened. This is an unclassified report and was from the time of it's release. Hence, the spotty information on the two individuals who did sustain physical damage.

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In the current world climate, much is being made of the scariest scenarios a talking head or fear dealing reporter can conjure up. Even more is being left to the imagination and imagination is never a good thing on topics like this. The human mind tends to fill in bad details by instinct and survival. It's just how we're wired to think and keep ourselves breathing in the face of threats which aren't entirely understood or explained.

I hope presenting this report may take a little of the stigma out of at least one area of anxiety, should the worst come to pass by either deliberate action OR complete accident someday by a nuclear warhead being detonated near where anyone here may live. God forbid, we all hope it doesn't ....but this one area can be understood, anyway.

Good thread, S&F

Dangers of nuclear weapons and nuclear power plants are greatly overblown. There is huge and real danger obviously, enough so that exaggeration isn't needed, but for some reason still happens anyway.

Most ignorant people hear "radiation" and instantly think of their insides being cooked. They fail to understand how there is a large variety of types of radiation, some are basically harmless and some very dangerous. Just like the fools freaking out about Fukashima thinking that people in the USA were getting radiation poisoning from Fukashima, even though the type of radioactive fallout that reached the US is the type which COULD cause cancer in 30-40 years, not the type that gives you radiation poisoning. Truth and logic aren't these people's strong points.

I wonder how many people are going to come into this thread and call you a shill etc, saying the government is lying, and that everyone on the planet would go blind the second a single nuke goes off anywhere on the planet. That's the type of behavior I've seen a lot of lately, the "OMG Fukashima was an extinction level events!!!!!" or any other overblown ridiculous fear of nuclear weapons and/or power.

Well if you are close enough and receive enough radiation, you're more than likely going to get cataracts and go blind if you cannot receive surgery to remove them.

Cataract induction

The timespan for developing this symptom ranges from 6 months to 30 years to develop but the median time for developing them is 2–3 years.[9]

2 gray of gamma rays cause opacities in a few percent
6-7 gray can seriously impair vision and cause cataracts

en.wikipedia.org...-Coggle_.26_Lindop-9

Interesting fact from the Hiroshima anniversary I attended in 2008...
*Shameless plug*
www.abovetopsecret.com...
*Shameless photo plug*


When the US bomber Enola Gay flew over top Hiroshima and dropped the bomb many people saw this and thought it was the pilot ejecting and that the plane was going to crash.

So, people applauded.... and watched this 'figure' fall to the ground.

This is why so many people in Hiroshima suffered blindness, they literally watched the bomb fall until it exploded into that flash of light.

Originally posted by WaterBottle
Well if you are close enough and receive enough radiation, you're more than likely going to get cataracts and go blind if you cannot receive surgery to remove them.

Cataract induction

The timespan for developing this symptom ranges from 6 months to 30 years to develop but the median time for developing them is 2–3 years.[9]

2 gray of gamma rays cause opacities in a few percent
6-7 gray can seriously impair vision and cause cataracts

en.wikipedia.org...-Coggle_.26_Lindop-9

Yow! 6-7 gray is a HUGE dose. You're not really going to care if you go blind after receiving 7 prompt Gray of radiation. You're going to look like Toxie Jr in about a week.

reply to post by Agit8dChop

I'd be interested in what you may have on verified cases out of Hiroshima and Nagasaki. This report covers it in a couple places for investigations done by follow-up teams as soon after the blasts as they could reasonably get in there, given all the circumstances. I was surprised at the findings as much as the rest. The media and popular culture would seem to have portrayed this entire phenomenon rather poorly in the end?

Hiroshima-Nagasaki. Information on flash-blindness effects at these bursts is almost impossible to obtain or verify. Reference 9 states that "The Ophthalmological Survey Group which studied the Hiroshima-Nagasaki casualties investigated the impairment of visual acuity following the two detonations. No case of flash-blindness lasting for more than about 5 min. was reported among the survivors."

(Pg. 15)

Then a bit later in the report, data following the immediate aftermath and initial period...

Hiroshima-Nagasaki: Surveys of effects after Shots Hiroshima(about 20 kt at 1850 ft) and Nagasaki (about 20 kt at 1650-1850 it) in 1945 state that the only instance of retinal burn to have been reported is that noted by Oyama and Sasaki. A 23-yr old girl at 2 km from the hypocenter at Hiroshima was searching the sky, looking for the plane at the time of the flash. She developed symmetrical opacification of both corneas, and permanent central scotomata of both eyes.

Reference 15 states that the faces of many survivors were severely burned,accompanied by loss of skin, and often of the eyebrows and lashes. Yet none examined had permanent corneal opacities attributable to ultraviolet or infrared radiation. It is postulated that this effect may, in part, .e due to the facial characteristics of the Japanese, i.e., narrow eye openings and protective overhang of the upper lid. Many people interviewed stated they were looking at the sky, some at the plane, some at the parachute. However, no lesions of the fundus were observed, and only one patient other than the first one mentioned lost vision in an eye. The second case, it was believed, suffered a vitreous hemorrhage. Some Japanese survivors developed cataracts with time; these are thought to be the result of ionizing radiation.

(pg 20 / 22 (A chart takes pg 21) )

The whole thing did make for very interesting reading. A bit over my head on the math (equations are all spelled out for those who can read them for meaning) but the majority appears to be in basic language by Gov't report standards. It's certainly not quite what I expected.

Then again, it wasn't until recently I'd even realized the US and Russia had detonated multiple nuclear warheads in the high atmosphere/low reaches of space, either. Obviously not something that has been advertised and listed far and wide over the years.

The more I read and learn about the history of atomic and nuclear testing/development as it actually happened vs. how it's presented in popular culture and media, the more I realize just how far from truth the "popular" presentation actually is for so much of it.

Some worse... Most, far less so than is normally depicted. I suppose that's a positive thing to find if nuclear weapons actually see release in either of the two major crisis zones across the world right now?

* An odd thing on this ... Several specific instances are described of people developing retinal burns/damage after a fair amount of time (Months or even a year and more) beyond the time of exposure, whether it was the radiation or other causes. So apparently, doing just fine afterward as some American soldiers and Airmen during testing reported for instance, is no promise of a lack of visual effects in the long term.

From the Atomic Archive:
www.atomicarchive.com...

Flash blindness is caused by the initial brilliant flash of light produced by the nuclear detonation. The light is received on the retina than can be tolerated, but less than is required for irreversible injury. The retina is particularly susceptible to visible and short wavelength infrared light. The result is a bleaching of visual pigment and temporary blindness. Vision is completely recovered as the pigment is regenerated.

During the daylight hours, flash blindness does not persist for more than 2 minutes, but generally lasts a few seconds. At night, when the pupil is dilated, flashblindness will last for a longer period of time.

A 1-megaton explosion can cause flash blindness at distances as great as 13 miles on a clear day, or 53 miles on a clear night. If the intensity is great enough, a permanent retinal burn will result.

Retinal injury is the most far-reaching injury effect of nuclear explosions, but it is relatively rare since the eye must be looking directly at the detonation. Retinal injury results from burns in the area of the retina where the fireball image is focused.