I've tried a number of glasses without prescription to test the blue blocking. They are available from the websites (Zenni, EyeBuyDirect, Gunnar, jandsvsion, e

I've tried a number of glasses without prescription to test the blue blocking. They are available from the websites (Zenni, EyeBuyDirect, Gunnar, jandsvsion, etc) or from amazon and excepting Gunnar can have the cost no more than $10. The glasses are "hit and miss" with the blue blocking. I don't know if the process is partially manual, but the amount of blue light that gets blocked is not always the same between two pair from the same manufacturer. Different manufacturers use different technologies to block the blue, some of which block almost nothing. Once I got a pair that blocked enough blue light, though, I really noticed a difference in eye-strain and length of time I could look at the monitor. The cheapest and best, strangely, is the plastic amber lab eye covering. Those block far more than any other pair of glasses and work the best for me.