Picked up a new Haswell iMac the other day and I'm noticing a very strange problem. My eyes cannot seem to focus properly on this thing at all. I've been adjusting brightness all over the place but for years use somewhere between 40-60% depending on other lighting conditions and haven't had a problem. This is also my 3rd or 4th 27" iMac and I don't recall any significant issues with the others, including my Ivy Bridge model I sold a few months back. I started having minor eye strain problems a few years back and picked up some Gunnar glasses which helped a bit but this is totally different. I have 20/13 vision and I can't seem to focus on this thing. My eyes physically hurt after about an hour and everything is slightly blurry, all the time. Anyone else ever come across this? I've tried adjusting brightness even further and have also tried using F.lux which is indeed nice, but isn't helping with the eye strain. My MBA and Dell monitors in my office seem mostly fine. I think some of the issues are carrying over after looking at the iMac but my Air and the 2412M monitors are MUCH better if I spend a few minutes on them alone. I have an eye appointment in the morning just to make sure nothing crazy is going on but I could swear it has something to do with this iMac. Any similar experiences or other things I could try would be helpful, I'd rather not have to return it and figure out a non-iMac solution (which means either a Mac Pro or an all laptop configuration). Just to note: I've even changed up the lighting in my office which has been the same for years and there is no glare on the glass screen in it's position (no overhead lights or windows).