You will definitely not want to return to your old monitor. Previously I was using a 15" monitor before I upgraded to a U2311H, and my, the difference is extremely big. I don't even want to touch the old monitor now .

Try lower the brightness and change the RGB display mode to cool.

How long u has been using this monitor? just buy recently? Only this monitor make ur eyes pain? Or maybe ur monitor distant with ur sits?

How low is your brightness? Are your room well lit when you viewing your LCD?
Try lower the contrast as well? Try adjust to the RGB to warm instead?

LCD has much much lower radiation over CRT any days, I'm surprise you're able to withstand a CRT while not a LCD, it just probably the light emission a bit high, especially the contrast part.
For your information, CRT rays (Gamma, UV, etc.) is way much harmful than LCD, so let just say you probably just overreacted?
Try to tone down the brightness to 0, this should give you the minimum brightness. But, I don't see anyway to work with that kind of brightness.
And lastly, make sure your room's light is well lit, if it's much dim than your monitor than lower the monitor brightness, usually your eyes should adjust accordingly when surrounding lights is brighter, giving you a slightly lower brightness feels on the monitor.
If your room's main light is very dim, then get some desk lamp, put it beside your monitor, it should give you proper well lit environment.

the con of lcd was too bright (due to backlight), some eye are too sensitive with bright light (including me which using minimum brightness on any lcd devices), and yes i prefer any phosphor base display rather than lcd, actually the radiation are within the safe level,and we human are exposed to many radiation in the modern world (e.g microwave based communication). As long as your eye feels comfortable(rather it is dim or bright), its fine. As for my assumption, many eye problem happens because of too much dependent on light causing pupil(anak mata) not use to dark environment, the eye also need to practice, thats why god create night and day