Drift of ocular alignment following strabismus surgery. Part 1: using fixed scleral sutures

Aims : To evaluate the postoperative alignment drift following traditional strabismus surgery utilizing direct attachment of muscle to sclera. Methods : The ocular alignment drift (change from the first postoperative week) of 106 patients who underwent scleral fixation strabismus surgery at age 0.5 to 35 years with 5 years maximal follow-up was analyzed. Results : There was a mean undercorrection drift of 4.6 + 8.9 PD at distance fixation (p=0.025) and 3.4 + 7.6 PD at near (p=0.053) for all subjects, and 11.3 + 8.6 PD distance (p=0.008) and 10.6 + 6.0 PD near (p=0.016) for exotropic patients. Recession surgery produced an undercorrection drift of 5.3 + 8.8 PD (p=0.021) at distance fixation. Esotropic patients and those undergoing unilateral recession/resection surgery had no significant drift. Patients overcorrected at the one week postoperative visit later developed an undercorrection drift at distance (10.3 + 7.9 PD, p=0.002) and near fixation (5.5 + 9.2 PD at 36 months, p=0.041), while undercorrected patients showed no significant drift and largely stayed undercorrected. Conclusion : Fixed scleral-suture strabismus surgery generally produces a postoperative undercorrection drift, especially following recession surgery, exotropia or overcorrection at the first postoperative week.