Dear Evgeni Metodiev,
The major goal of Dr. Bates' idea is relaxation of your tightened eye muscles. The method works effective at the early stage of myopia when you were young, -- probably a case of functional myopia. However, after wearing glasses for 8 years, apparently a large part of your myopia is the result of over-elongation of eyeball--i.e axial or structural myopia. I have no idea about the nature of your myopia.
Anyway, it can be confirmed by ultra-sound scanning if you wish.
Once the elongation of the axial length has ocurred, there is no means to shorten it other than banding surgery on the surface of cornea for the purpose to reduce amount of myopia.
Before purchase anything, visit www.i-see.org under library about whole set of Dr. Bates' book. Don't miss it!
I have no idea about the devices you mentioned.
Relaxation of eye muscles beneficial to spastic myopia (they are the first sign of myopia, early stages), and preventing from getting worse case. For your case and young age, you should think the way to prevent your vision from deteriorating. Your eyes have to be used for many many years.
Do you know "modern civiliation" creates a great masses of neasightedness? Because we spent a lot at computer and close work which the eye is not designed for.
Please think in depth about the idea to use PLUS lens at time of your close work to relax tension of the focusing muscles. There are many links at the site to those web sites advocate PLUS lens for prevention.
The concept of plus is to reduce your regular minus glasses.
You have to consider using a WEAKER minus glasses for your nearwork.
Yes, the lesser tension within eyeball, the lower risk retina tears off itself! Take care of your own personal visual and health welfare in the long run.