Preoperative factors influencing effectiveness of surgery in adult strabismus.

To identify preoperative factors which influence the effectiveness of strabismus surgery in adults, we retrospectively reviewed the records of 179 patients > 15 years old (131 with exotropia, 48 with esotropia) who had had combined recession and resection surgery for correction of horizontal strabismus. Eighteen preoperative variables were evaluated; those with significant influence on the surgical outcome, measured by the degree of change in deviation per millimeter of surgery, were identified by stepwise regression analysis. In patients with exotropia, preoperative distance deviation and average spherical equivalent were significant predictors of outcome at both 1 month (multiple R, 0.37) and 6 months (0.63) after surgery. In esotropic patients, significant variables at 1 month (multiple R, 0.57) and 6 months (0.77) were preoperative distance deviation and dissociated vertical deviation (DVD). Preoperative distance deviation is the common significant influence on surgical effectiveness for horizontal strabismus in adults, for both exotropia and esotropia. Additional significant predictors are average spherical equivalents in exotropic patients, and DVD in esotropic patients.