On a personal experience, watching TV at close range gave me eye strains and dizziness upon reaching the age of 35. It's getting worse from then. Tired strained eyes which resulted to temporary worsening of eyesight yes. Pero pahinga lang ng konti eyes, balik na sa dati. Headache yes. Pero tulog mo lang ok na.
So now, I keep a good distance whether it be PC or HDTV even though I would rather sit closer. Thank God for wireless keyboard and mouse.
In any case and for whatever reason, I don't think it's healthy to stay close to any type of viewing panel for long periods of time. Radiation emission is still an issue btw, but with LCDs, they are much less than those of CRT.
Combination of bad genes, regular exposure to large TVs and large high contrast PC monitors I think contributed mainly to my daughter's terrible terrible eyesite at such a young age. Good thing super thin lens technology has improved so much.
In Japan, it's still quite common practice for companies to issue a "special apron" to the lady staffs to protect them against VDT. It's kinda like radiation suit and they definitely look dorky wearing apron in the offfice but they don't mind using it all day.