Rabbit Model - Retrobulbar Hyaluronidase Injection

Author: Mike Clague Aesthetic Nurse BSC   Date Posted:17 February 2019 

Role of Retrobulbar Hyaluronidase in Filler-Associated Blindness: Evaluation of Fundus Perfusion and Electroretinogram Readings in an Animal Model 

Catherine J. Hwang, M.D.*, Hamzah Mustak, M.D.†‡, Adit A. Gupta, M.D.†, Regina M. Ramos, B.S.†, Robert A. Goldberg, M.D.†, and Gary R. Duckwiler, M.D.§ 



The purpose of this study is to determine the effect of retrobulbar hyaluronidase on hyaluronic acid gel-induced ophthalmic artery occlusion in a rabbit model. 


New Zealand red rabbits were used to simulate hyaluronic acid gel filler-associated vascular occlusive blindness. Ophthalmic artery occlusion and subsequent ischemia were confirmed by both retinal fundus photography and electroretinogram changes. Retrobulbar hyaluronidase 1,000 IU was injected 30 minutes after occlusion. Fundus photography and electroretinogram changes were recorded at 30, 60, 90, and 120 after administration of retrobulbar hyaluronidase. 


A total of 6 rabbits were used, for a total of 12 eyes. Four eyes were used as controls. Of the 8 experimental eyes, 2 eyes had recorded partial occlusion and 6 eyes had fully occluded ophthalmic arteries by angiographic evaluation. One of the partially occluded eyes demonstrated some improvement in perfusion 60 minutes after injection of retrobulbar hyaluronidase; however, electroretinogram readings remained flat over the 120-minute period of observation. Six eyes with completely occluded ophthalmic arteries showed no improvement in retinal perfusion with corresponding flat electroretinogram readings at 120 minutes following retrobulbar hyaluronidase injection. 



In this rabbit model, 1,000 IU of retrobulbar hyaluronidase administered 30 minutes after occlusion failed to reverse obstruction or restore function following hyaluronic acid gel occlusion of the ophthalmic artery. 



This is an interesting study.  It is sad to see the study did not yield better results for retrobulbar injection of Hyaluronidase.  As injectors it is important we stay on top of the latest publications.  The retrobulbar injection of hyaluronidase may not be as effective as we hope when it comes to reversing blindness after HA filler.  

It would have been interesting to see another arm of this study that allowed for repeated treatments of hyaluronidase over a few hours (similar to the De Lorenzi protocol). 

Get the full clinical paper here https://journals.lww.com/op-rs/Citation/2019/01000/Role_of_Retrobulbar_Hyaluronidase_in.7.aspx

Trying to avoid ischemic events with dermal fillers.

We teach-

  • Keep your needle tip moving at all times ( micro-movements)
  • Consider a large bore 22g cannula in areas that are risky
  • Do not treat noses or glabellas with dermal fillers, it just isn't safe
  • Inject slowly, gentle pressure on the plunger
  • Inject small amounts less than 0.1ml
  • Avoid semi-permanent 


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