Hello,Filling tear-troughs with Restylane is one of the most delicate areas you might use this product so it is best to take a careful, slow approach. Understand that injectible fillers works well only for mild tear-troughs. More severe cases should focus on surgery. It is best to take things slowly when filling tear-troughs. I recommend half of a syringe (.5cc) under each eye per session. It usually takes 2 sessions, but sometimes 3 to get the optimal fill. You will want to wait about a month or more between sessions to make sure the previous session is completely stabilized.. If you also need filling under the outside corners of your eye, then starting with 1cc under each eye is often the starting point.. Finally, do not use anything except for a hyaluronic acid filler under the eye. There are a lot of hyaluronic acid brands with the most common ones being the Juvederm and Restylane lines of fillers. Products like Radiesse and Sculptra should never be used in this area.Best Regards,Dr. A