Hacker News Reader

Comment by jessriedel | Hacker News Reader

The weak expert consensus is now that the largest contributor to near-sightedness is reduced exposure to sunlight as a young child which causes the eyes to grow slightly differently. Do places above the Arctic circle have higher rates of near-sightedness?

EDIT: apparently there is a correlation, but it seems to me it's not as strong as the sunlight theory would have suggested.

http://onlinelibrary.wiley.com/doi/10.1046/j.1395-3907.2003....

View on HN

Perhaps there's correlation between sunlight exposure and being out in "large spaces" where the majority of what you're seeing is farther away than your homes' walls. Having developing eyes focus on a mountain panorama or distant trees across a lake leads to different stresses on the eyeball ... or perhaps some different training for physiological systems that deal with focus.

> Perhaps there's correlation between sunlight exposure and being out in "large spaces" where the majority of what you're seeing is farther away than your homes' walls.

This was one of the other leading hypotheses for a long time. More recent data came down pretty decidedly on UV light rather than focal range. See my other comment: https://news.ycombinator.com/item?id=16248851

I can't understand how sunlight exposure could be more of a problem than excessive close-range work (reading books, etc.) during formative years.

Biology doesn't have to make sense, and a lot of it doesn't. There are weirder correlations in there.

That is a misconception and has been debunked (same goes for reading in dim light), I been a kid like that and I basically spend all day since the last 15y in front of a computer and I have near perfect eye sight. The "screen time" is not at fault per se if you get enough outside time. The reason is not just any "sunlight exposure" but it is about UV radiation that is important for the development of the eye.

The linked study doesn't agree that "that is a misconception and has been debunked". It says it's true:

> As indicated by other reports, myopia was found to be associated with ... education and nearwork.

The above linked study is from 14 years ago. (I linked it because it addressed arctic communities.) It's the more recent work has mostly ruled out the near-work explanation.

> ...for many years there was an assumption that long hours of study indoors, staring closely at books (near work) and never focusing on distant objects, led to myopia. This study belied that error.

http://sunlightinstitute.org/research-shows-sun-exposure-red...

> ...increased load of near work was not significantly associated with odds of myopia when factors including parental myopia, demographics, and outdoor activities were adjusted for.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3930282/

wrong conclusion...it is because those people are not doing this outside ;) so yes if you sit all day at home and read books it won't be good but the reason is not the reading distance. I remember as a kid my parents always said "don't sit so close to the TV"...same story there

Just a note, that with polar night comes a) long winter with sun and snow, and b) polar day.

Further, polar night in Tromsø ends around 21st of January, while the midnight sun starts around 21st of May - that's roughly 17 weeks going from the sun not rising, to the sun not setting - more than an hour of difference, week to week on average (0-24 hours, in 17 weeks).

[ed: of course, the change isn't linear: https://www.timeanddate.com/sun/norway/tromso ]

Reply on news.ycombinator.com