Subnostr

Japan is in the top 3 nations for highest myopia rates in young adults, with some studies showing as high as 80% having nearsightedness.

For comparison, US is at 30-40%.

A common characteristic in myopic adults is elongated eyeballs (when eyeballs are misshaped).

Lack of time spent outdoors is considered to be a factor that increases myopia rates, yet I see more kids outside in Japan doing extracurricular activities than in US.

One thing I’ve noticed is that just about everywhere you go there is a lack of natural lighting so people use lights.

There’s no strong causal link between indoor lightning and myopia but I suspect it’s plays a much larger role than anyone imagines or cares to admit. I’d be curious to see if Singapore or South Korea also has a culture of keeping the lights on during the day 🤔

Loki 2y ago

What about northern regions? Russia, Scandinavia, Alaska? These places would have long periods every year that people just have to stay indoors more. But on the other side, the time they do spend outside they are exposed to a lot more blue light and ultraviolet, especially if it snows really heavily.

Also, there is a bunch of nutrients important to vision. I imagine that the japanese have a far lower typical consumption of saturated fats and stearates and so on. I believe that this has an impact on nerve function, since nerves are isolated from each other by these fats.

I personally have developed a vision problem that is purely from nerve damage caused by Thiamine deficiency, and here in the west, that can be related to not eating bread, which is by law in most western countries loaded up with B1. I don't know what other things it can cause, but it can mess up convergence and does seem to increase fatigue induced weak focus.

This could also be a general muscle nutrient problem, since magnesium, for one, in deficiency, can cause muscle weakness and cramping. This and the B1 thing are related with me via alcohol, which also seemed to have something to do with visual migraines, which mess up the brain's processing of the centre of vision where we read, and may not necessarily be actually caused by mechanical/optical problems.

And lastly, the japanese adopted computers a lot earlier than the rest of the world on average. Could it also have something to do with staring at screens for more hours especially during childhood, causing a simple lack of muscle development and training for pulling focus and releasing it as is needed when you are navigating the outside world.

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Discussion

HoloKat 2y ago

A lot to unpack here but I don’t think computers have anything to do with it

Loki 2y ago

I've always been wary of getting used to glasses because they literally (for myopia) reduce the tension required to focus the lens. So, not a permanent issue, but one that takes time to recover from. Use it or Lose it as they say. Antifragile systems need to be worked to increase capability, and muscles are exactly this. A little strain makes them grow more fibres and that increases the lens ability to stretch.

And conversely, if the diet or some other factor causes the lens to be harder, this will also have a similar effect as not working the muscle, but this will be difficult to reverse.

IMO, for myopia, glasses should be a second line not first line treatment, because the lens naturally hardens (and yellows) with age. Nutrients and exercises can address the lens flexibility. And the other thing is that the lenses themselves filter some types of light, which may be another factor.

There's a lot of moving parts in the vision system. it would be hard to positively narrow down reasons for the japanese higher than average use of corrective lenses for short sightedness.