This question, recently on Quora.  Here’s my response:

I can speak with some authority on this topic, having reversed my own -5.00 diopters of myopia.  
I also have thousands of students working on controlling their own myopia, including a number of Sinagporeans who successfully stopped their myopia progression and even reversed it (glad to introduce you, if you like for some first hand insights).  It may sound far fetched at first, but if you’re willing to look at science and ignore retail optometry crying foul, you’ll find out that the answers aren’t difficult at all.
Myopia is first a strain symptom, often referred to as NITM (near-induced transient myopia), http://scholar.google.com is a good resource to look at thousands of studies and reviews on this initial phase of myopia.  It’s a muscle strain (of the ciliary) due to excessive close-up focus.
This muscle strain (or spasm) is then commonly treated with minus lenses, which cause hyperopic defocus on the retina especially during close-up, and ultimately are responsible for lens-induced progressive myopia.  This is also well documented in innumerable studies going back some four decades, many of which you can also find on http://scholar.google.com.  Once you begin wearing minus lenses, and in particular wear them for close-up, your myopia tends to increase at a rate of 0.50 to 0.75 diopters per year.
Singaporean kids study a lot more than others (though Hong Kong has an incidence rate for myopia exceeding 90% for school children as well).  There are also genetic markers that have been found to increase the susceptibility of axial elongation of the eyeball.  This isn’t “genetic” myopia, merely the eye being more susceptible to growing longer due to hyperopic defocus from minus lenses.  Unfortunately this genetic marker is found in some Asian population more than others.
Close-up and lens wear is the primary issue though, there was a study showing myopia progression in Singaporean kids in Singapore, and Singaporean kids who had relocated to Australia.  Same genetics, same culture, different environment, the relocated kids myopia progression has been found to be significantly lower.
All of this is often criticized by retail optometry, although the science is near unequivocal.  There is a hundred billion dollar a year lens industry driving the treatment narrative, and the profit motive and conflict of interest stifles a lot of reasonable discussion on the topic.
Here’s more on the basic biology of the eye, to help understand myopia:  The Eye & Myopia
And here’s a link to a whole range of brilliant studies on the subject, a must-read for anyone serious about understanding what is happening today with the global myopia epidemic:  The Elephant In The Room
Compare this to the other answers to the question, including from Quora’s CEO, a medical doctor, and an optometrist boasting 20 years experience.  Everyone else is giving the same standard vague und inconclusive answers.  If anyone took just a little bit of time to look at the body of science available (I could hardly have been the first to put the obvious pieces together), we’d have better answers to myopia, from more professionals who reach myopes every day.
 
Cheers,
 
– Jake