There has been so much focus on display technology EMF and Temporal dithering as one and only cause for severe eye strain. And I agree, it is one of the most severe direct cause, that effects whole nervous system, potentially rendering user of a technology incapable of doing productive work and supporting himself/herself financially for work that requires the use of computers. But, there are other causes too, and if you are aiming for better health, including better eye and nervous system health, you should consider these hidden but very serious causes: