Children who see clearly underwater
bbc.com
bbc.com
They will still be unfocused, though, of course. From the article, it sounds like you need to practice for a while before the eye learns how to focus underwater:
> Gislen wondered whether the Moken children had a genetic anomaly to thank for their ability to see underwater or whether it was just down to practice. To find out, she asked a group of European children on holiday in Thailand, and a group of children in Sweden to take part in training sessions, in which they dived underwater and tried to work out the direction of lines on a card. After 11 sessions across one month, both groups had attained the same underwater acuity as the Moken children.
Perhaps this only works for children, who seem somehow more biologically adaptable? The body is quite adaptable in general so I would believe it that people who swim regularly could see better underwater. I'm glad to have the science though to study the effect more rigorously.
[edit: added "and diving"]
Wow... I didn't know that. Losing my mask and panicking while diving has always been a concern of mine. I'll have to try this out. Regardless of being able to see clearly, it'd be great to just not be bothered by an onslaught of seawater.
That's one of those things that take me by surprise when I discuss peoples' relation with the sea. I never thought there was a problem with having your eyes open underwater. I'm Greek and I've spent a lot of time in the sea when I was young, so I must have just gotten used to it.
Mind you, my eyes still get red but I don't actually feel them stinging or experience anything unpleasant.
I can totally understand being worried about panicking in the sea, though, especially if you're diving. I snorkel, and even so, when I go under it's always in the back of my mind that anything can go wrong and I need to keep my wits about me at all times. I've been close to drowning twice too, so yeah. Need to be careful.
The sea is not your friend :)
They said that it took a while to learn to cope, but once they did their short-sightedness didn't affect everyday life at all, apart from not being able to read. This included things like playing tennis.
I'm -4.5 in both eyes, and, interestingly, if I take my glasses off I can just about make out the words I'm typing here without adjusting the zoom level; mostly from shape. Zooming in a couple of notches makes the letters appear. Blurry and distorted, but legible (just). I can totally believe that practice would make me reasonably functional.
Maybe it's just something you need to be aware of culturally, to even attempt it?
Are you able to consciously refocus your eye?
By this I mean stare at an object (with one eye), and consciously make it go in and out of focus, whilst always staring straight at it.
I find that I can do this to a certain extent - is this something that most people can do?
Then again, I have weird eyes in general. One has almost perfect vision, the other is really bad (don’t remember the exact prescription, but the big “E” on the vision chart is just a dark blur when I don’t have my single contact in).
Yes. Mentally, I move my point of focus from the monitor "backward" into space -- like an imaginary 3D cursor anchored on my screen, then moving away from me along the ray of my eyesight. Almost as if I was going to peer around the monitor and look for something behind it, except without actual movement. Imagine doing that, and it might help.
It's easier to do with one eye shut than with them both open.
I can also (through conscious effort) expand my pupil size. Looking in the mirror if, instead of focusing on one point, I try to look at a larger area (without moving my eyes) my pupils will expand.
If so, this isn't really what I mean.
I mean with just one eye, being able to consciously refocus that eye. For example, looking at this writing on your screen able to make that go in and out of focus.
If you know any trick to make things sharper that'd be great.
Then again, if your vision isn't perfect there are tricks like placing pressure on the eyeball or squinting which can change the focus, but are probably not too healthy in the long term.
Best advice is to see an optometrist instead. Although, I have found that they aim to correct vision for 6 metres in red-green light. If you're reasonably young and myopic, ask for a slightly stronger minus power to get better blue vision at infinity (at the risk of more eye strain close up). The extra -0.25 makes a huge difference for me, really allows depth perception to "click" properly.
On top of this, one thing that surprised me was the difference in correction between red, green and blue light. The refractive index of the eye varies according to light frequency such that blue is focused approximately 2 dioptres more than red. If your myopic eyes are corrected for red at infinity, you won't be able to focus on any blue light further than 0.5m away! Not really a concern in the natural world but very noticeable in a server room full of blue LEDs or on a screen with blue text on black.
The difference in power between red and green is less but still useful enough for some vision tests. If you can focus on red traffic lights but green ones are blurry, this is why - consider a stronger power as long as it doesn't strain your near vision.
Only trick I know is getting the right prescription glasses...
Although I couldn't do it in salt water, it stung my eyes too much but that might also be due to me learning to swim in pools instead of the sea.
> The kids had to dive underwater and place their heads onto a panel. From there they could see a card displaying either vertical or horizontal lines. Once they had stared at the card, they came back to the surface to report which direction the lines travelled. Each time they dived down, the lines would get thinner, making the task harder. It turned out that the Moken children were able to see twice as well as European children who performed the same experiment at a later date.
PS: I still have better than 20/20 vision. But, I think your eyes age faster than most people suggest as I can't see as well even at just 35 vs 15.
I wonder if this refers to salt or fresh water. Maybe both, if the density delta between the two is trivial.
Gislen was able to test a few Moken adults in the same way. They showed no unusual underwater vision or accommodation – perhaps explaining why the adults in the tribe caught most of their food by spear fishing above the surface. “When we age, our lenses become less flexible, so it makes sense that the adults lose the ability to accommodate underwater,” says Gislen.
> She thought the first theory was unlikely, because a fundamental change to the eye would probably mean the kids wouldn’t be able to see well above water. A simple eye test proved this to be true – the Moken children could see just as well above water as European children of a similar age.
The last 30 submissions of bbc.com were submitted by about 25 different accounts.
Why do you think this article doesn't belong here?
a liter of seawater collected in marine surface
waters typically contains at least 10 billion
microbes and 100 billion viruses[1]
[1] http://www.the-scientist.com/?articles.view/articleNo/36120/...
I'll dig up the ref on request, but that's just ... staggering.
https://www.reddit.com/r/dredmorbius/comments/1vyanj/viral_s...
Facts show that people perfectly deal with all these viruses and bacteria.
By the way, did you check the fauna on your keyboard? Or inside you digestive system?
I was thinking more along the lines of first-world people, especially children. E.g. exposing "European children on holiday in Thailand" to what I stereotype as the fetid waters off the coast of third world countries.
It may be a stereotype, but that doesn't mean it's not true. I'd venture that the phrase "sewage treatment plant" is not part of the vernacular there.
Thailand ain't exactly third world. (The waters can be dirty, though.)