Hyaluronidase and its use during ophthalmic blocks
Let’s talk a little bit about hyaluronidase. Hyaluronidase enhances the spread of Local Anesthesia with Ophthalmic blocks
Hyaluronidase is the enzyme that breaks down hyaluron or hyaluronic acid, a polysaccharide found in connective tissue.
Hyaluron is present throughout the human body where friction and or movements occur. (Koornneef)
Thus it is no surprise that we find Hyaluron making up the dense matrix of connective tissue of the orbit and retrobulbar space. (Singh)
The enzyme, Hyaluronidase, hydrolyzes the hyaluronic acid, in the retrobulbar space behind the globe, increasing the permeability through the connective tissue and allowing a more uniform distribution of the local anesthetics in the orbit. Hyaluronic acid or hyaluron regenerates itself in about 48 hours.
I use 2-3 units of hyaluronidase / ml of LA in my Peri-Retrobulbar Intraconal Blocks and see an effective LA onset 1-minute after I complete the block.
Hyaluronidase is manufactured from 3-different sources, bovine, ovine and human recombinant.
It is important to know the different types of medications or combinations of medications available to you as a clinician, and how they may or may not affect each patient. For more detailed information about Hyaluronidase, check out my accredited course Pharmacology for Ophthalmic Blocks. https://orbitalblocks.com/
References:
Koornneef L. ConnectiveTIissue Apparatus of The Human Orbit. What About It?
Proc. 3rd Int. Symp. on Orbital Disorders, Amsterdam, 1977.
Sing, SP & M. Nikifosak. The Biochemical Composition of Human Retrobulbar Connective Tissue. Separate Experiments Vol. 32, pp.395-396,
Berkhauser, Basel ,1976.