Good habits for good vision
I have low myopia and I am still in process with this, so I can't personally guarantee for big improvements, but even if wouldn't get to 20/20, I find this method very useful for prevention of eyesight worsening. Since I got into it, I started spending more time outside, less on the phone, I started taking regular breaks from PC work, habits which ophtalmlogists regard as good too. The practice of what we call "Active focus" is the main principle of this method, not plus lens. And Jake always advises us not to force the eyes etc., so if we take him seriously and not rush for fast improvement (which is not possible anyway), I don't think this can do damage.