Can being on the computer while in the dark be bad for your eyes?

my mom tells me that if I use the computer while the room's light switches are off that it's bad for your eyes. I'd like to know if that's true. Or reversed, is playing with the lights ON bad either? She says that even if the screen is as dim as possible it's still bad. Is it? Or in my case, The room isn't completely pitch black ever. so that's another factor.