Deep topical fornix nerve block versus peribulbar block in one-step adjustable-suture horizontal strabismus surgery

We compared the efficacy of deep topical fornix nerve block anaesthesia (DTFNBA), which does not paralyse the extraocular muscles, with peribulbar block in patients undergoing one-step adjustable-suture horizontal strabismus surgery. Patients with a vertical, oblique squint were excluded from the study.

We studied 100 patients, allocated randomly to two groups. Group 1 (n=50) received peribulbar block with 5 ml of 1:1 mixture of 0.5% plain bupivacaine and 2% lignocaine supplemented with hyaluronidase 300 i.u. ml(-1). Group 2 (n=50) received DTFNBA with placement of a sponge soaked in 0.5% bupivacaine deep into the conjunctival fornices for 15 min. No sedation was given to either group. Analgesia was assessed by direct questioning of patients during the procedure. A three-point scoring system was used (no pain = 0, discomfort = 1, pain =2). If the pain score was 1, the patient was asked to look in the opposite direction to decrease the tension on the periosteal attachment of the muscle to relieve discomfort. If the pain score was 2 at any stage of the operation, general anaesthesia was given.

In Group 2, significantly more patients (15) experienced discomfort than in Group 1 (no patients) (P<0.05), but general anaesthesia was not needed.

DTFNBA is a useful technique for intraoperative adjustable-suture strabismus surgery. It does not alter muscle tone, thus allowing the surgeon to adjust the muscle sutures intraoperatively, and reducing the incidence of under- or over-correction of the squint in the immediate postoperative period.