Abstract
Purpose: :
To determine the effect of horizontal rectus muscle surgery on distance-near incomitance.
Methods: :
Prospective evaluation of all patients who had horizontal rectus muscle surgery between 12/09 and 9/10. After > 30 minutes of monocular occlusion, prisms and alternate cover testing was performed with the preferred eye fixing on an accommodative target in primary position at distance (6 meters) and near (0.3 meters) with the appropriate refractive correction. Measurements were obtained at the pre-operative examination and the first post-operative examination within a week of the surgery. The change in distance-near incomitance induced by strabismus surgery was calculated. The choice of strabismus surgery was at the discretion of the surgeon. Patients were excluded if they had evidence of muscle fibrosis, muscle paralysis, or if they had simultaneous surgery on a vertical muscle.
Results: :
Seventeen patients were included. Six patients had esotropia, treated with medial rectus muscle recessions. Eleven patients had exotropia, treated with a recess/resect procedure (5 patients), lateral rectus muscle recessions (5 patients) or medial rectus muscle resection (1 patient). The change in distance-near incomitance was clinically insignificant in all patients, measuring less than 5 prism diopters in 15 patients and less than 8 in all patients. There was no clinically significant change in distance-near incomitance in any patient, regardless of preoperative deviation or choice of surgical procedure.Traditionally, medial rectus muscle surgery is performed for deviations greater at near and lateral rectus muscle surgery for deviations greater at distance. Archer et al.1 in a retrospective study concluded that distance-near incomitance decreases regardless of the choice of surgery. However, fusion was a confounding factor. Our study used monocular patching in order to suspend fusion and to evaluate the effect of the actual muscle surgery.
Conclusions: :
Horizontal rectus surgery does not have a clinically significant effect on distance-near incomitance. Therefore, it is not necessary to consider distance-near incomitance when choosing between medial rectus and lateral rectus muscle surgery.
Keywords: strabismus • strabismus: treatment