What I discovered by owning both Gunnar amber & clear/crystaline lens glasses is they really help me avoid eye strain and headaches. I bought my amber lens first and discovered their benefits but, unfortunately, they altered colors enough that I had to buy a clear lens pair for color critical work. So if you only want to buy one pair I recommend clear lens. Both amber and clear reduce my eyestrain and headaches during long screen sessions but, if you ever use for applications were color accuracy is important, i.e. digital art, video or photo editing, etc. the amber lenses alter color perception.
2nd this. I bought ambers but wanted to lose the orange tint to everything and got clear ones. Use them almost everyday. They really do help with eye strain