Juvederm can improve under eye hollowing

Juvederm and Restylane, when injected judiciously, can improve the "hollowing" of the lower eyelid region.  The material should be placed in a deep plane (under the muscle), or it will appear bluish. 

There are many potential causes, however, of dark circles.  If the appearance of dark circles is due to loss of soft tissue of the lower eyelid region, then injection of filler will help. 

The appearance of dark circles though can be due to several causes including allergy-related venous congestion, an inherited or acquired pigmentary problem and even small capillaries (blood vessels) can contribute significantly to the appearance of dark circles.

I suggest you consult with a qualified health professional concerning these matters.  Good luck.