Calling Sculptra doctors! What method do you use for Sculptra in the temples?

TEMPLE SCULPTRA: As far as I am aware there are two methods; may I ask which do you prefer and why? 1. Needle, down to the periosteum, 'near the bone'. 2. Cannula, intrafascial. I am TERRIFIED with the risk of blindness and the Cannula method seems safer in that regard. May I please have your thoughts? another question: Does repeated Sculptra make a facelift impossible in the future, even if I only get it in the temples? Thank you!