Sir,

We appreciate the interest shown by the authors Youssef et al in our article1 titled ‘Orbital cellulitis after peribulbar anaesthesia for cataract surgery’. They point out that the orbital cellulitis in our case could well be an allergic reaction to hyaluronidase used during peribulbar anaesthesia. They felt that sensitisation to hyaluronidase occurred as a consequence of peribulbar block to the fellow eye operated previously, resulting in a type 1 hypersensitivity reaction on peribulbar block to the second eye. This is a possibility; however, we note that all three cases reported by Youssef et al were apyrexial, there was lack of purulent discharge, and orbital cellulitis presented 1–2 days postoperatively after uncomplicated peribulbar anaesthesia. Their patients spontaneously resolved without antibiotic treatment. In our patient, symptoms and signs suggestive of infection were presence of purulent discharge from the affected eye and leucocytosis on blood testing. There was occurrence of trauma to periorbital soft tissues during the peribulbar block, which could possibly have resulted in access of skin flora to the orbit and cellulitis. The inflammation settled only after a course of broad-spectrum intravenous antibiotics.

We note that in the cases reported by Minning et al2 and Taylor et al,3 the allergic reaction occurred within minutes of the retrobulbar block, was associated with local pruritis and the oedema responded to intravenous administration of diphenhydramine hydrochloride. Kirby et al4 have also reported allergic reaction following use of hyaluronidase. Their patient developed periorbital oedema and chemosis within minutes of administration of local anaesthetic. Systemic symptoms such as sweating, nausea, and hypertension were also seen. In our patient, the ocular examination was unremarkable on the first postoperative visit and periorbital oedema developed 2 days following injection of the local anaesthetic. There were no systemic or local signs suggestive of an allergic phenomenon in our patient. Hence, we feel that in our case the diagnosis was orbital cellulitis and not an allergic reaction to hyaluronidase.