I did a full-scale test of the blinkers, based on this forum thread, a few months ago. It was remarkably effective for my laptop, a Lenovo Ideapad 100S, which I already do pretty well with, but which causes me symptoms if I use the screen for too long a time. I was now able, with the blinkers, to use my laptop seemingly indefinitely without symptoms.
With my tablet, however -- a Samsung Galaxy S3, if I remember the specification correctly --, which causes me terrible symptoms almost immediately, the blinkers offered some help, it seemed, but it really was of no practical utility since after a few minutes the symptoms were still very bad (less dramatically instantaneously awful, but still quickly very awful).
After about five or six weeks of consistent use of the blinkers, generally for multiple hours every day, I started having vision problems when I was not using the blinkers. Without the blinkers, I could no longer focus on text, whether in a printed book or on a screen: the letters appeared double, and blurry. My general distance vision seemed unaffected, but my vision when I tried to read something without the blinkers was totally messed up.
I completely stopped using the blinkers, and the vision problem continued. It took about 3 or 4 (worrying) weeks until the problem resolved and I can now thankfully read text normally again.