Orbital inflammation secondary to a delayed hypersensitivity reaction to sub-Tenon's hyaluronidase.

We report a rare case of a delayed orbital inflammation with raised intraocular pressure as a result of hyluronidase allergy following sub-Tenon's anaesthesia. Here, we have shown evidence to prove the orbital inflammation to be an allergic response to hyluronidase with a skin patch test. This is the first case to our knowledge of a delayed hypersensitivity reaction to sub-Tenon's hyluronidase comprising of an initial exposure to hyluronidase in the fellow eye with no subsequent allergic response, but with a subsequent delayed reaction to hyluronidase during a second eye cataract surgery. This case demonstrates hyaluronidase allergy should be considered as a differential diagnosis among patients presenting with acute post-operative orbital inflammation, even if there is a history of previous exposure to hyaluronidase in the fellow eye with no subsequent allergic response.