An In Vitro Model Assessing the Penetration of Hyaluronidase through Optic Nerve Dura for Management of Hyaluronic Acid Facial Filler Embolism.

[BACKGROUND] Blindness from ophthalmic or central retinal artery embolism is one of the most devastating complications of cosmetic filler facial injections. A proposed therapy to mitigate visual loss is prompt retrobulbar injection of hyaluronidase into the retrobulbar space. Despite Zhu et al. showing a lack of evidence and very limited published literature for reversing visual loss with this intervention, it is still widely accepted as a treatment for filler-related emboli. The purpose of this study was to evaluate the penetration of hyaluronidase through optic nerve dura using an in vitro model.

[METHODS] At study conclusion, five 1-cm-long segments of fresh optic nerve were obtained and injected with highly crosslinked hyaluronic acid filler, then ligated on both ends in a watertight fashion. The sections were immersed in three concentrations of hyaluronidase solution for 24 hours. Histopathologic examination of the specimen was performed to assess the presence of filler.

[RESULTS] The optic nerve sections were 1.1 cm (range, 0.8 to 1.2 cm). Three were immersed in 20 ml of 1500 IU/ml hyaluronidase solution and two were immersed in saline as control. After 24 hours, there was a persistence of hyaluronic acid within the optic nerves.

[CONCLUSIONS] There is a lack of evidence for penetration of optic nerve sheath by hyaluronidase. This raises question about the effectiveness of retrobulbar injection of hyaluronidase in reversing filler-related blindness. Further studies are needed before this can be adopted as the treatment of choice.

[CLINICAL QUESTION/LEVEL OF EVIDENCE] Therapeutic, V.