I think we need to keep in mind that some of us react badly to computer screens for different reasons and it also appears that no two people are alike with this either. Sensitivities vary. Some here most definitely react to the light component. The brighter it is, the worse they feel and these same people probably feel bad in bright sunlight for example. For others, it’s a function of the sharpness of the screen and how the image is presented to the brain.
I know that I am triggered solely by the visual aspect. On a screen that sets me off it doesn’t matter what I do to the brightness or contrast, or whether I even stick a matte finish over the screen or put on sunglasses. It still sets me off. And as I said before it’s not necessarily the screen itself as I once thought. Simply changing a video card on a screen at work made it unusable. Suddenly the sharpness had changed and letters appeared almost 3D as they lept off the page. It sent me into one of the most severe states of disorientation I’ve ever experienced on a screen and took me a couple of days to recover from.
The iPad 2 also set me off but at a low level. Two weeks on it and I adjusted. This did not occur on the third gen iPad which is very sharp yet not bothersome to look at really – not like the MacBook Air was. I’m sure it would have been ok on the iPad 3 if I had persisted for weeks but then maybe not. Maybe there is a point where no matter how much exposure you allow, the brain just doesn’t get there and so you have to move on.