The soft tissue landmarks to avoid injury to the facial artery during filler and neurotoxin injection at the nasolabial region.

The aim of this study was to locate the course of the facial artery and to propose "the danger line" vulnerable to vascular complications following filler injection. The entire facial soft tissues were harvested from 14 Thai soft embalmed cadavers as a facial flap specimen. Measurements of the distance, the depth, and the diameter of the facial artery were done at level of the oral commissure and the nasal ala. The distance between the facial artery and the oral commissure was 15.3 ± 3.7 mm and the depth from the skin was 11.1 ± 3.1 mm. The distance between the facial artery and the nasal ala was 6.7 ± 4.4 mm and the depth was 11.6 ± 3.7 mm. The diameters of the facial artery at level of the oral commissure and the nasal ala were 2.6 ± 0.8 and 1.9 ± 0.5 mm, respectively. Maximum risk of arterial complication from dermal filler injection lateral to the oral commissure is located approximately 15 mm at the depth of 11 mm. High risk of arterial injury at the lateral nasal ala is located at 7 mm with the depth of 12 mm.