Diplopia and ptosis following injection of local anesthesia without hyaluronidase

In a university ophthalmology department, a cluster of postoperative diplop ia and ptosis cases occurred in the initial 3 months after hyaluronidase (W ydasel (R)) became unavailable for use with injection anesthesia. These cas es suggest that hyaluronidase, when used with injection anesthesia, may pro tect extraocular muscles and nerves from the toxic effects of local anesthe tic agents. The spreading action of hyaluronidase facilitates uniform diffu sion of anesthetic agents. This prevents elevated extracellular tissue pres sure, a cause of ischemic damage to extraocular muscles or nerves. Hyaluron idase may also prevent focal accumulations and concentrations of local anes thetic agents, which at high enough levels may cause myotoxic or neurotoxic damage, fibrosis, and contracture of extraocular muscles or nerves. (C) 20 01 ASCRS and ESCRS.