Problems with coatings on glasses

I have two pairs of glasses, both of which have a non scratch coating. Since i have arrived in Thailand, both of these coatings have distorted, and i can hardly see out of them, i can only think that this because of the heat here. Although i think i never leave them in direct sunlight.

Has anyone else had any problems like this ?

Glasses in Thailand seem quite expensive, well at the opticians in Robinsons Complex, anyway. I have found that it is much cheaper to send away for them on the internet , i get mine in USA, although i am European. You must know your exact prescription, in order to do this, but you can save lots of cash, particularly if you want more expensive lenses, varifocal etc.
But then i still have the problem with the coatings ........

That maybe down to the quality of the coating. I've had some lenses done with coatings over here and had problems with them (coloured watermarks showing up like you'd see with oil on water). When another optician's shop was trying to sell me the coating on a subsequent pair of glasses I mentioned my experiences and they assured me that their coatings were a better quality and that I wouldn't have that experience. So I went ahead and opted for their better quality (and more costly) coating and have had no problems.

Should have gone to specsavers seriously though I have 2xpairs of varifocals that I got from specsavers in uk and have not had a problem with either of them..I also bought some reading glasses for my g/f from an opticians while in Sakon Nakhon, no problems there either!