How to get rid of the rainbow effect on the Otterbox Defender for the iPhone 5?

I have a Defender series case for my iPhone 5. I just started get the rainbow effect on the built in screen protector. I tried the baby powder trick and it didn't work. I was wondering if anyone knew any other tricks besides the baby powder one.

Never hear of the baby powder trick but quite frankly its best to just take that plastic shield off just use an adhesive screen protector that sticks to the screen. Thats what I did and I looked so much cleaner.

I had someone else tell me that he put an anti glare screen protector on his iphone before he put the otterbox on and it eliminated the problem. Personally I havent tried that so idk for sure. But at that point i dont see the need for the otterbox screen to be on there if he was using a screen protector on the phone already lol.