Hyaluronidase allergy: A rare cause of periorbital inflammation

Hyaluronidase is a bovine or ovine testicular protein that is used as an adjunct to co-administered medicaments and fluids to enhance their dispersion and absorption through the degradation of hyaluronan. While it is a known potential allergen, there are few reports of hyaluronidase hypersensitivity. A 56-year-old lady presented 8 hours post glaucoma surgery with ipsilateral lacriminorrhoea, periorbital erythema, oedema, proptosis, pruritis and conjunctival chemosis. Right ocular motility was restricted and visual acuity was reduced. The reaction settled with oral corticosteroids and antihistamines. Hyaluronidase allergy was confirmed on skin prick testing. Hyaluronidase allergy is rare. In the few cases reported, reactions occurred at various doses and were acute (intraoperative), early (within hours), intermediate (within days) or delayed (within weeks). Anaphylaxis has also been described. Primary sensitization appears to be a prerequisite for most reactions. The variability in onset of symptoms and the response to skin testing would suggest that type I and type IV hypersensitivity may both contribute to this response. In this case, the timing fitted with a late phase type 1 reaction. This case shows that despite being less common than haemorrhage for acute reactions and infection for delayed reactions, allergy can account for orbital inflammation following ophthalmic surgery.