While shopping in the local supermarket yesterday, I was surprised to find this display on one of the shelves.

I also realize that I should have taken a pamphlet with me, as well as a picture of the boxes for the glasses, as seen in the picture to read more about it.
This answer at Skeptics.SE shows that there are in fact probably no long-term benefits of wearing pinhole glasses, but my question is...
What potential harm/side effects can be caused in the short and long-term from wearing this type of eyewear?