Orbital Dynamics and Efficacy of Retrobulbar Anesthesia With and Without Hyaluronidase in Vitreoretinal Surgery

Purpose: To compare retrobulbar anesthesia injection (RAI) with hyaluronidase and without hyaluronidase in vitreoretinal surgery using clinical efficacy measures and orbital manometry (OM). Methods: This prospective randomized double-masked study enrolled patients who had surgery using an 8 mL RAI with or without hyaluronidase. Outcome measures were clinical block effectiveness (akinesia, pain scores, need for supplemental anesthetic or sedative medications) and orbital dynamics assessed by OM before and up to 5 minutes after RAI. Results: Twenty-two patients received RAI with hyaluronidase (Group H+), and 25 received RAI without hyaluronidase (Group H-). Baseline characteristics were well matched. No differences in clinical efficacy were found. OM showed no difference in preinjection orbital tension (4 ± 2 mm Hg in both groups) or calculated orbital compliance (0.6 ± 0.3 mL/mm Hg, Group H+; 0.5 ± 0.2 mL/mm Hg, Group H-) (P = .13). After RAI, the peak orbital tension was 23 ± 15 mm Hg in Group H+ and 24 ± 9 mm Hg in Group H- (P = .67); it declined more rapidly in Group H+. Orbital tension at 5 minutes was 6 ± 3 mm Hg in Group H+ and 11 ± 5 mm Hg in Group H- (P = .0008). Conclusions: OM showed faster resolution of post-RAI orbital tension elevation with hyaluronidase; however, there were no clinically evident differences between groups. Thus, 8 mL RAI with or without hyaluronidase is safe and can achieve excellent clinical results. Our data do not support the routine use of hyaluronidase with RAI.