this occurs if filler placed too high in skin resulting in a bluish tint. If concerned, discuss with your surgeon.
Or I would recommend you discuss with a Board Certified Dermatologist with expertise with Restylane
Restylane under the Eyes
From the photo it is not possible to see if these are dark circles or the Tyndall effect. You definitely can get the Tyndall effect from improper placement of Restylane. If you are concerned you should return to your treating physician and it can be reversed by injection of hyaluronidase to dissolve the Restylane.
Tyndall or Dark skin
It is possible for the dark skin to be caused by the Tyndall effect. Another cause could be the veins that in that area pool blood which give the darker appearance under the eye -- fillers help camouflage this, but you may need a procedure to thicken up the skin such as a laser treatment which increases the collagen in the skin.
It is very common for people to have darker skin under the eyes and this can benefit from a skin bleaching cream such as hydroquinone +/- kojic acid. Our office uses ViPeel Bleaching cream and we have met with good success.
If it is the Tyndall effect, it will resolve in a few months or may need a medication such as Vitrase (hyaluronidase) to dissolve and dissipate the excess Restylane.