Well I'm leaning towards both telepathy and a visual cortex. In A2 theres a scene where Ripley fires the flamethrower above the eggs to which the queen replies with a movement of her head toward the guards. If indeed they are telepathic, it would seem needless for her head to move toward the guards as she could send the back off message telepathically. Also if the queen could not actually see Ripley firing off the flame thrower then that would indicate that they can read our own minds as the queen reacts to this. Not only that but when Ripley does set the eggs on fire why does the Queen scream? Can she see them burn or does she have a telepathic link to the eggs?
One more point, during the escape scene the queen looks at the elevator button and is clearly looking at it, this seems to contradict the telepathy theory – unless they have both senses which is what I think.