Surgery for Esotropia With a High Accommodative Convergence/Accommodation Ratio: Effects on Accommodative Vergence and Binocularity

Abstract

To determine the effectiveness of strabismus surgery as an alternative treatment for high accommodative convergence/accommodation (AC/A) ratio (nonrefractive accommodative) esotropia. Twenty-three consecutive children with an AC/A ratio of 5:1 or greater and a distance-near disparity of 10 prism diopters (PD) or more were studied in a prospective design. Each patient was treated by recession of both medial rectus muscles for the full amount of esotropia measured at near fixation through the full distance hyperopic correction. The magnitude of eso deviation, the AC/A ratio, and the grade of binocularity were measured before and a minimum of 4 months after strabismus surgery. Surgery reduced the mean preoperative eso deviation at near fixation by a factor of 4 (from a mean of 37 PD to a mean of 9 PD). Surgery eliminated the need for bifocals in 96 percent of the patients. The grade of binocular fusion or stereopsis improved in 70 percent of the patients, remained unchanged in 26 percent, and was degraded in 4 percent. Three (13 percent) of the children became exophoric; none of the children were exotropic. These results demonstrate that strabismus surgery is an effective alternative to the long-term use of bifocals in the treatment of high AC/A ratio esotropia. Surgery may be more effective than bifocals in restoring normal stereopsis and binocular fusion.