All I know is that both LCD&plasma cause less eye strain than CRT. It has something to do primarily with refresh rate. The default 60hz refresh rate caused a flicker in CRTs that was very annoying after a short time. You could increase your CRT's refress rate to 72 or more and the effect would become unnoticable. LCD's don't seem to flicker at all, or at least, not at 60 Hz. LEDs which have been around forever, are just beginning to be used as a display technology and I haven't heard any stats on how they compare to LCDs or CRTs or Plasmas.