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"Effectiveness of retrobulbar hyaluronidase injection in an iatrogenic blindness rabbit model using hyaluronic acid filler injection".

BACKGROUND
Blindness caused by soft tissue filler injection is the most tragic complication, with no standard treatments until recently. Retrobulbar hyaluronidase injection has been proposed as the treatment, but its effectiveness in visual compromise remains to be determined. The authors aimed to determine the effectiveness of retrobulbar hyaluronidase using soft tissue filler in an iatrogenic blindness animal model.


METHODS
New Zealand rabbits were used to simulate the hyaluronic acid (HA)-associated vascular occlusion model. A volume of 0.7-1.6 ml of HA filler was injected into the internal carotid artery to create a retinal artery occlusion. The rabbits were administered retrobulbar hyaluronidase (3000 IU) at different post-obstruction time points (5 and 10 min). No intervention was given to the control group. Fundus photography was performed before and immediately after the filler injection and immediately after the administration of retrobulbar hyaluronidase. Electroretinogram was performed after 60 min to confirm the retinal reperfusion and electrophysiological function.


RESULTS
All of the experimental eyes recorded total occlusion after HA injection. Three eyes with completely occluded retinal artery following retrobulbar hyaluronidase treatment showed improved retinal reperfusion by fundus photography and corresponding electroretinogram. Despite administration of the retrobulbar hyaluronidase injection, one completely occluded eye showed no improvement in perfusion. All of the control eyes recorded complete occlusion 1 h following HA filler injection.


CONCLUSION
Retrobulbar hyaluronidase may be an effective evidence-based treatment option for humans. Hyaluronidase concentration and injection time are the important factors for faster recovery, but additional studies are still required.