The Depth of the Facial Artery, Meta-analysis.

Summary

This first meta-analysis quantifies facial artery depth at five standardized facial levels, reporting mean depths and 95% CIs. The data support superficial injection (≤4.5 mm) at the oral commissure level and highlight substantial depth variability in the nasolabial region, advocating ultrasound assessment in upper nasolabial areas.

Key Findings

• Across 12 studies, mean FA depths (95% CI) were: cheilion level 9.72 mm (6.50–12.94), between oral commissure and nasal alae 10.34 mm (5.24–15.44), nasal alae level 9.21 mm (7.05–11.38), between nasal alae and medial canthus 4.68 mm (4.04–5.31), medial canthus level 2.38 mm (1.38–3.38).
• Safe superficial filler injections up to 4.5 mm are suggested at the oral commissure level.
• Marked variability between nasal alae and oral commissure indicates benefit of pre-procedural ultrasound in upper nasolabial fold.

Clinical Implications

Injectors should limit depth to ≤4.5 mm at the oral commissure and consider routine pre-injection ultrasound mapping in upper nasolabial and periorbital areas where FA depth is shallow and variable. Training curricula can incorporate these quantitative benchmarks.

Limitations

• Heterogeneity in measurement techniques (cadaveric vs imaging) and anatomical landmarks across studies
• Lack of patient-level modifiers (age, sex, BMI, ethnicity) limiting individualized risk estimates

Future Directions

Prospective ultrasound-based mapping registries stratified by demographics and facial subunits; integration with AI-guided injection planning tools and simulation-based training.