Asymmetry is a common trait we all share - no person's face is perfectly symmetrical, and this is for a good reason: we would look rather strange if we were.
So, to start off, asymmetry is normal, and while we try to recreate symmetry in our sculpting, achieving precise outcomes can be tricky. This can be explained by either small errors in estimation during injections (location as well as the volume of product placed), or it could be due to fat pad asymmetries in the face. These fat pads are where fillers are placed, and any asymmetry can result in the filler spreading slightly more on one side than the other.
So to answer your question, asymmetry can be:
- Genetic
- Due to slight misjudgement during filler placement
- Due to the inadvertent spread of fillers to surrounding areas
As Ellanse is a non-Hyaluronic acid filler, the only way to correct this asymmetry is by injecting the side which is under-filled to mimic the opposite side.
More often than not, asymmetries that we see in the mirror are insignificant in reality - how others see us in the 3-dimensional space is rather different from the 2-dimensional image we see in the mirror. As such, if asymmetries are mild, you can rest easy and just let it be.