RESUMEN
BACKGROUND: The enzyme hyaluronidase (HA) is an adjunctive in retrobulbar anaesthesia (RA) that is used during ophthalmic surgery to improve the efficacy and speed of nerve blocks. Although uncommon, HA has been shown to be a potential cause of allergic responses. CASE REPORTS: We describe three patients who experienced an allergic reaction to HA following ocular surgery in our department and provide an extensive overview of the literature on HA in RA. CONCLUSIONS: Although rare and mostly benign, allergy to HA should be included in the differential diagnosis when chemosis, proptosis and restriction of eye movements occur after parabulbar or retrobulbar anaesthesia. The authors feel that the beneficial effect of HA in small volumes of RA warrants its use despite this potential complication.