Purpose: To review and determine the long term outcome of surgery for intermittent exotropia in children.
Cases: A total of 666 cases were reviewed. They were 15 years old or younger and underwent surgery for intermittent exotropia during the preceding 22 years. Bilateral recession of the lateral rectus muscles was performed in 349 cases. Unilateral recession of the lateral rectus and resection of the medial rectus muscles was performed in 298 cases. One and four muscle procedures were performed in 19 cases. The outcome was evaluated at 1 month and 4 years after surgery.
Results: Orthotropia or mini-microtropia was achieved in 401 patients (60.2%) one month after surgery. Bilateral recession of the lateral rectus muscles was more effective than unilateral recession- resection. Out of these 401 patients, half, 199 patients (49.6%) showed orthotropia or mini-microtropia 4 years after surgery while the other half, 202 (50.4%), became exotropic. Bilateral recession of the lateral rectus muscles was also more effective in producing orthotropia or mini-microtropia on a long term basis than unilateral recession-resection. The rate of orthotropia or mini- microtropia was higher when the patients were operated before 3 years and after 11 years of age.
Conclusions: There was a strong tendency for intermittent exotropia to recurr and drift into permanent exotropia during 4 or more years following surgery. It is advocated to aim at orthotropia during the immediate post- surgical period and to avoid overcorrection. Early surgery is not necessary when the patient is over 4 years of age. Bilateral lateral rectus recession is the preferred surgical procedure.