> Usually we close our eyes in reflex due to intense light from the Sun, but on day of an eclipse, the intensity of sunlight is decreased and we can view the Sun through naked eyes. While we watch a solar eclipse without any protection to our eyes, the ultraviolet rays penetrate our eyes and cause retinal burn, leading to loss of central vision.
[1]: https://www.indiatoday.in/science/story/partial-solar-eclips...
The UV light polymerizes collagen in presence of vitamin B. They did experiments by repairing cornea that way:
https://pmc.ncbi.nlm.nih.gov/articles/PMC3018104/
"The aim of this study is to evaluate the safety and effectiveness of riboflavin-ultraviolet type A (UV-A) light rays induced cross-linking of corneal collagen in improving visual acuity and in stabilizing the progression of keratoconic eyes.
...
The eyes were saturated with riboflavin solution and were subjected for 30 min under UV-A light
...
Cross-linking was safe and an effective therapeutical option for progressive keratoconus."
I think that this is probably one of the reasons why suntanned skin usually looks like it is in better condition mechanically-wise.
Another my favorite Sun exposure related correlation - vitamin D deficiency and autism, as couple studies on Somali immigrant population in Minnesota and Sweden - where such dark skinned population naturally gets very low on vitamin D - showed such correlation as autism rates in that population is higher than back there in Somali (and that would explain the correlation of low sunlight expo.
And my favorite pet theory is that Neanderthals with their large eyes adapted to the Northern latitudes were significantly impaired by spike of UV radiation - getting highly increased rate of early cataract and other eyesight damage - during that thousand years of magnetic field polar swap 40K years ago, and that caused them to lose to the Cro-Magnon who was coming out of Africa with more dark and smaller eyes more adapted to higher UV levels which are natural to Africa.
Apparently there has been an sharp rise in people coming in with retinal damage from staring at the sun. They didn't go into details why someone would do that, but reading this on HN I can start to guess.
There's seems to be a concerted effort at making people afraid of the sun. My guess is because the sun fixes a lot of problems, and problems mean profit.
Seriously, take a step back. If spending time in / looking at the sun was dangerous we wouldn't be here.
Aldous Huxley was taken in, unfortunately: https://en.wikipedia.org/wiki/The_Art_of_Seeing
I would guess it's dangerous nonsense, though there are plausible claims that shortsightedness is associated with not spending much time outside as a child so perhaps there's a slight link with something that isn't nonsense.
AFAIK that has nothing to do with the sun but rather with looking at things at a larger distance than at home.
An obvious thing perhaps worth mentioning: if you're shortsighted (or longsighted) then you see better in bright sunlight because the iris closes, giving you greater depth of field, so that might make people think/feel that sunlight "cures" myopia.
(On the other hand, if you have excellent eyesight then you see better in less bright conditions because your vision is being limited by diffraction at the aperture.)
Why not? People are still arguing in 2025 that the vast majority of the world's climate scientists are wrong about climate change, and there are even some who unironically argue that the Earth is flat. Science is dead. Long live "Whatever I want to believe is true and you're all wrong!"
For the naysayers, if looking at the sun is so bad, why is it not considered bad to look at the sun's reflection on the water? Additionally, when the sun is low, if you look at the brightness of the sunlight, it is less bright than some artificial light sources, and doesn't hurt to look at. How could this be bad?
Who said it's not? It may hurt you as fast but it's still bad for you.
https://www.aao.org/eye-health/diseases/photokeratitis-snow-...
People who spend more time in the sun have a low-moderate risk of melanoma, but higher risk of other skin cancers, vs those who spend more time indoors having a lower risk of non-melanoma skin cancer and a moderate-higher risk of melanoma cancer.
But I have noticed that my eyes get weaker after spending a lot of time indoors, like if I'm sick. Getting enough time in sunlight seems to be heavily correlated with better eyesight, both in my personal experience fighting farsightedness as a man in his 50s and with studies done on children regarding nearsightedness.
And there ya go, the rallying cry of every conspiracy theorist: "They don't want you to know, because money!"
Seriously, take a step back.
Yeah, seriously.
As a person w/ keratoconus I have read a fair bit about this treatment, corneal collagen crosslinking with riboflavin (C3R).
It does not repair the damage caused by keratoconus. It stabilizes the cornea and slows or halts progression. The collagen in the cornea naturally crosslinks (likely due to UV exposure) over our lives. My our late 30s our corneas are stable. For someone with keratoconus, where the cornea becomes progressively misshapen, stabilizing the tissue with UV (enhanced by riboflavin) slows or prevents further damage.
I was just a few years too early in my diagnosis to benefit from C3R. My eyes have been stable for the last 10 - 12 years. I wish I could have had C3R when my condition was first diagnosed back in my 20s.
Or autism among Somalis causes them, or their parents, to want to immigrate to Minnesota and Sweden?
It seems that autism got politicized and thus such various correlations, which may or may not be real causations, don't seem to get enough of proper scientific attention/resources. I mean, for example folic acid deficiency causes spina bifida, and it wouldn't be out-of-this-world if vitamin D (which is steroid) deficiency (or some other deficiency) would have affected prenatal development and structure of the brain which is just another body organ. Instead we spend tremendous amount of attention and energy on alleged vaccine-autism connection which hasn't been established even as mere correlation.
Yes - their whole body would be subject to the ageing effects of the sun.
> It seems unlikely that we would have evolved to have a single part of our body exposed to the sun while the rest wasn’t
And yet it's common for dark skinned people to have significantly lighter palms and soles of feet as they have less exposure to the sun.