To report the effectiveness of incorporating a central tenectomy on the recessed rectus muscles when treating large-anagle horizontal deviations.

Patients undergoing recession and central tenectomy were prospectively enrolled. The procedure entails making two longitudinal incisions, each 4 mm, on the muscle adjacent to sutures made during the recession procedure. With recession complete and muscle sutured to the sclera, the central flap is excised. The following variables were analyzed: expected correction (according to surgical dose tables), achieved correction (preoperative deviation minus postoperative deviation), and tenectomy effect (achieved correction minus expected correction).

A total of 16 horizontal rectus muscles of 16 eyes of 12 patients were included, 8 with exotropia and 4 with esotropia. In all patients, the median achieved corrections at distance (55D) and at near (53.5D) were significantly higher than the median expected corrections (45D for both distance and near [P 0.002]). The postoperative deviations at distance and near were lower in the unilateral surgery group. The tenectomy effects in the esotropia group for both distance and near were more pronounced than those of the exotropia group.

Central tenectomy of the recessed rectus muscles increased the effect of recession procedures without limiting ductions. There were possible greater effects in esotropia patients and recession-resection procedures.