Viscoelastic Evaluation of Different Hyaluronic Acid Based Fillers Using Vibrational Optical Coherence Tomography

Hylauronic acid (HA) is used as a viscoelastic in Ophthalmology during cataract surgery based on its high viscosity at rest, its ability to shear thin and dissipate energy during phacoemulsification. However, these properties of HA solutions would make them susceptible to migration when used as dermal filler materials. In this study, we apply a new technique termed vibrational optical coherence tomography (VOCT) to compare the physical properties of different HA solutions and fillers used in facial aesthetics. Results presented in this study suggest that HA solutions and HA dermal fillers have markedly different physical properties. HA solutions are highly viscoelastic with high % viscous losses while fillers tend to have lower viscous energy dissipation properties. Clinical observations suggest that the high loss fillers are injected more superficially in the face where tension and internal and external forces are more likely minimized giving tissue of the hands and lips more volume and allowing more natural movement. In contrast, the lower loss gels that are used to lift tissue, generally have a higher G’, and are injected deeper into the face where injection and internal forces are likely to be higher. It is concluded that HA filler gel design can be optimized by use of VOCT to evaluate the % viscous energy loss both in vitro and in vivo.