I bought a pair earlier this year and found that the glasses weren't as clear as expected, my guess is that at this price they aren't optical glass and I found them to make my vision ever so slightly more blurry.
JColumboThey do have a 20% magnification, which could explain why it felt a little blurry. That and the color shift makes your eyes adjust, and for some people that could mean blurred vision, headaches, etc. for a short period.
TY!