Needle versus Cannula to Treat Tear Trough: A Prospective Study Comparing both Methods.

Background: We aimed to clinically compare needle and cannula techniques in vivo with ultrasound and magnetic resonance imaging, to better understand the best technique and adverse events. Methods: Ten adults without previous fillers in the area were injected with hyaluronic acid (CPM 22.5 HA mg/mL) with a 25G cannula on one side and a Becton Dickinson syringe needle (31G 0.3 mL) on the other. The product was fractionated among two visits. Assessment was made at time 0d, 14d, 30d, 60d, 90d, 180d, and 365d with standard camera, Vectra H2, ultrasound, and magnetic resonance imaging. Level of satisfaction was also evaluated. Results: All the patients showed natural results with both techniques and a high satisfaction index. Cannulas were minimally less traumatic in terms of bruises. However, the product was applied in a more superficial layer and in a less precise manner, despite the fact that a deep technique was used with cannulas, depositing the product on the orbital bone. Patients reported a more noticeable change immediately after the procedure on the side treated with cannulas but less edema and a more comfortable procedure on the Becton Dickinson syringe treated side. None of the patients required hyaluronidase to dissolve overcorrection of the area, and no severe complications were observed. The product remained in most of them at day 365. Conclusions: Cannulas seem to be less traumatic regarding bruises, but less precise in vivo. Thin needles seem to be more precise with minimal trauma. However, this difference disappears during patient's evolution.