Improvement in Fusion and Stereopsis Following Surgery for Intermittent Exotropia

Purpose: To evaluate fusion stereopsis in patients with intermittent exotropia before and after strabismus surgery. Methods: Fifty-three patients (mean age: 11.8 years, range: 5 to 25 years) with intermittent exotropia were enrolled. Fusion was measured with the Worth 4-dot test. Near stereopsis was examined with Titmus and stereoscopic test charts (created in China by Shao-Ming Yan). Distance stereopsis was tested with random-dot stereograms produced by Tianjin Eye Hospital. All patients completed the tests preoperatively and 2 and 6 weeks postoperatively. Results: There were no statistically significant differences in stereoscopic test charts among groups preoperatively (P > .05) and postoperatively (P > .05) or on Titmus tests preoperatively (P > .05) and postoperatively (P > .05). Among 53 patients, the percentage of distance stereoscopic improvement was 49% after 2 weeks and 77% after 6 weeks compared to 13% preoperatively. Six weeks postoperatively, random-dot stereograms were significantly different in those younger than 7 years and older than 13 years (P < .05), as well as those 7 to 13 years and older than 13 years (P < .05). Fifty (94%) demonstrated peripheral fusion and only 21 (40%) demonstrated central fusion preoperatively. Six weeks postoperatively, all patients exhibited peripheral fusion and 52 (98%) demonstrated central fusion. Central fusion in patients with intermittent exotropia significantly increased after 6 weeks (chi-square = 42.29, P < .01). Conclusions: Patients with intermittent exotropia have good near stereoacuity preoperatively and postoperatively. Even if surgery is postponed until adolescence, distance stereopsis can still be recovered. Surgical intervention can restore central fusion and stereoacuity in patients with intermittent exotropia.