Apparently it's true, "action video games" (by which the author means First Person Shoot-em-ups) make your eyesight better.

"Action video game play changes the way our brains process visual information," Daphne Bavelier, professor of brain and cognitive sciences at the University of Rochester, said. "After just 30 hours, players showed a substantial increase in the spatial resolution of their vision, meaning they could see figures like those on an eye chart more clearly, even when other symbols crowded in."

Now I have a good excuse to finish Doom3 and finally get around to buying Quake 4.