As the clinical lead for hyaluronic acid filler augmentation trainings on my courses, I always, no matter the experience level of my students, begin each session with an anatomical of the tear trough region. Though it may seem redundant to some of the more experienced students, I still do so to stress just how critical anatomical understanding is for mastering tear trough treatments, perhaps more important than in any other non-surgical facial treatment.Mastery of this region's anatomy can not only prevent complications and improve patient outcomes, but it can also expand a practitioner's patient pool and build injection confidence. Of course, such lessons should focus on the structures that most-influence a practitioner's results as an injector. Here is a brief introduction to the key infraorbital ligaments and their significance for under-eye treatments involving hyaluronic acid filler.