The Long-Term Effect of Unilateral Lateral Rectus Muscle Recession for Moderate Angle Exotropia

In order to evaluate the long-term effect of single lateral rectus muscle recession for the moderate angle exotropia(20-3-PD), we retrospectively studied 30 cases which were recessed by 8-9mm. The average follow-up period was 35.8 month. At 6 month postoperatively, the success rate was 75% in 8mm recession group and 84% in 8.5mm group, 88% in 9mm group. At the last follow-up, the success rate was 62%, 38%, 22% respectively. The recession of single lareral rectus muscle for the moderate angle exotropia was successful during the early postoperative period. But, its success rate was gradually decreased in the long-term follow-up especially for exotropia over 25PD. So, we should consider to recess lateral rectus muscle more than 8-9mm or choose the classic surgical method such as both lateral rectus recession or recession-resection for exotropia over 25PD.

The Effect of Recession of Single Lateral Rectus Muscle

The authors studied the effect of recession of single lateral rectus muscle. One lateral rectus muscle was recessed by 9.0-9.5mm on 21 patients with 20-25 delta exotropia from October 1991 to February 1994. The average corrected amounts of exodeviation were 13.36 by 9.0mm and 17.9 delta by 9.5mm. The Success rate was 70.0% in 9.0mm recession group with follow-up of 12.5 months in average, and 54.5% in 9.5mm recession group with follow-up of 17.0 months. The success rate was 62.0% in all patients. The success rate was gradually decreased in long term follow-up. The limitation of lateral gaze and lateral incomitancy were not observed. The recession of single lateral rectus muscle is a safe, predictable and simple procedure for the treatment of moderate angle exotropia less than 25 micro gram.