Sir,

The injection of local anaesthetic agents into the episcleral, or sub-Tenon’s, space is widely used for cataract surgery. Since its introduction 9 years ago, no serious adverse events have been reported.1,2 We have recently encountered a case of orbital cellulitis following sub-Tenon’s anaesthesia and phacoemulsification with lens implantation. To our knowledge, this is the first report of an infectious complication of sub-Tenon’s anaesthesia.

A 63-year-old female patient underwent phacoemulsification with posterior chamber lens implant under sub-Tenon’s local anaesthesia. Preoperatively, Benoxinate drops were instilled, and a single injection of 2 ml Lignocaine 2%, 2 ml Bupivacaine 0.75% and 500 IU Hyaluronidase was administered into the inferonasal sub-Tenon’s space. The eye was then prepared with an aqueous solution of povidone-iodine 10% (BetadineR), and a routine phacoemulsification procedure was performed. At the end of the operation, a subconjunctival injection of Gentamycin 20 mg and Betamethasone 2 mg was given.

On the first postoperative day, the patient complained of ocular pain. There were no unusual findings except moderate postoperative anterior uveitis. The patient was commenced on G MaxitrolR (Dexamethasone 0.1% with Neomycin and Polymyxin B) six times a day. One day later visual acuity was 6/4 unaided, but the pain persisted. There was non-tender swelling of the eyelids and infraorbital soft tissues, chemosis and conjunctival injection, and moderate anterior uveitis. Intraocular pressure and fundoscopy were normal. Intolerance to any of the drugs used before, during, and after surgery was unlikely, as the patient had undergone contralateral phacoemulsification following the same regime 2 months earlier. Topical steroids and antibiotics were increased in frequency, but lid swelling and chemosis worsened slightly over the following days (Figure 1). In addition, the patient developed pain on eye movements, mild limitation in all directions of gaze, and mild proptosis (1 mm) of the affected eye. Four days after surgery, a clinical diagnosis of orbital cellulitis, with a differential diagnosis of surgically induced scleritis was made. A CT scan and ENT consultation excluded sinusitis. Ultrasound B scanning showed scleral thickening (Figure 2).

Figure 1
figure 1

Mild chemosis, periorbital erythema and lid oedema right side.

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Figure 2
figure 2

Posterior scleral thickening on B-ultrasound scan.

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Because of previous anaphylactic reactions to penicillin, the patient was treated with intravenous Ciprofloxacin 200 mg twice daily, and the swelling completely resolved over the following 3 days, supporting the diagnosis of an infectious aetiology.

There are two possible explanations for the development of orbital cellulitis in this patient: either this was a coincidence, although no other risk factors for orbital infection were identified, or bacteria from the ocular surface or skin flora entered the episcleral space during or after the sub-Tenons’s injection of local anaesthetic. Orbital cellulitis has been reported following cataract surgery with peribulbar3 and retrobulbar anaesthesia.4 When the now widely used technique for sub-Tenon’s anaesthesia was first described, the possibility of infections was discussed, but considered a ‘theoretical risk’.1 So far, no cases of orbital cellulitis have been reported. A simple way of reducing the risk of bacteria entering the episcleral space consists in administering topical povidone-iodine (BetadineR) solution after instilling topical anaesthetic drops and before opening the conjunctiva.2 Topical povidone-iodine decreases the number of bacterial colonies on the conjunctiva by 91%.5 We recommend a change in the current practice of sub-Tenon’s anaesthesia by ensuring that topical povidone-iodine is applied before the episcleral space is opened.