I think that saying "if you look at the sun for a moment, you will go blind forever" is bullshit. Similar to most anti-Trump bullshit, it is just ignorant dreck and propaganda.
It is meant to scare people in hopes that this scaremongering would prevent them from doing truly dangerous stuff, such as staring at sun for long durations of time. Similar to DARE propaganda and such.
Think about this. When you drive in the morning, evening, or mountains, you often get sun right in front of your eyes. And you still keep on driving. Surely, you did not go blind from that.
Similarly, there are many cases when you catch a glimpse of the sun, say, operating a crane, or doing some outdoor work overhead. I was craning stuff last week and the sun was right over where the hook was. It was extremely annoying and I tried very hard to look at it as little as possible. But still, the sun was right there.
I have no doubt that staring at sun for a long time (more than a second) would damage your eyes. It is uncomforable enough that people do not do that.
Now, welding shades are made for professional use to look at powerful electric arcs right in front of the person. They block most light, UV and such.
To say that a shade 10 is somehow dangerous, defies common sense.
I have shade 10 welding shades (with gold layer on the outside) and I tried them to look at the bright sun. They seem to work well, although the sun appeared to be a bit too bright.
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