Surgical outcomes of unilateral recession and resection in intermittent exotropia according to forced duction test results

PURPOSE: To compare the surgical outcomes of unilateral lateral rectus recession–medial rectus resection (RR) according to forced duction test (FDT) results with those of conventional RR in intermittent exotropia. METHODS: A total of 129 patients aged 3 to 10 years with intermittent exotropia who underwent RR between 2006 and 2011 were included. The operator compared the tension of the lateral rectus (LR) between both eyes. When FDT results were asymmetric, RR was performed on the eye with more LR tension. RR was performed on the nondominant eye when FDT results were symmetric. Patients were divided into two groups; one group (n = 64) underwent RR without FDT (RR group) and the other group (n = 65) underwent RR considering FDT results (RR-FDT group). Success, recurrence, reoperation rates and cumulative probabilities of success were evaluated in both groups. Surgical outcome was considered satisfactory if the distance deviation in the primary position was between ≤ 10 PD of exophoria/tropia and ≤ 10 PD of esophoria/tropia. Recurrence was defined as an alignment of > 10 PD of exophoria/tropia, and overcorrection defined as > 10 PD of esophoria/tropia. Reoperation for recurrence was recommended for constant exotropia ≥ 14 PD at distance. RESULTS: The total follow-up periods were 4.4±2.3 years in the RR group, and 3.9±2.0 years in the RR-FDT group (P = .310). In the RR group, 50 patients (78.1%) were successful, 13 patients (20.3%) had recurrence, and 1 patient (1.6%) had overcorrection at 2 years after surgery. In the RR-FDT group, 58 patients (89.2%) were successful, 5 patients (7.7%) had recurrence, and 2 patients (3.1%) were overcorrected. The recurrence rate at 2 years after operation was significantly lower in the RR-FDT group (P = .045). Recurrence rates during the follow-up period were 5.6% per person-year in the RR group and 2.7% per person-year in the RR-FDT group. Reoperation for recurrence was performed on 7 patients (10.8%) in the RR-FDT group and 16 patients (25.0%) in the RR group (P = .035). Postoperative sensory outcomes were similar between both groups. CONCLUSIONS: The forced duction test was useful in reducing the risk of recurrence at 2 years after surgery when RR was performed on the eye with more passive tension of the LR. Intraoperative FDT may be considered to choose which eye to operate on when planning RR in intermittent exotropia.