effect of limited tenon and intermuscular membranes dissection on the outcome of horizontal strabismus surgery

purpose: to evaluate the effect of limited dissection of tenon sheath on the outcome of horizontal strabismus surgery. methods: patients with horizontal strabismus, aged between six and 50 years, were enrolled in this non-randomized study. patients with pattern and vertical strabismus or a history of strabismus surgery were excluded. the strabismus surgeries consisted of bimedial recession (bmr), bilateral recession (blr), and recession and resection (r&r;) depending on the type of horizontal strabismus and presence of amblyopia. the participants were divided into the case and control group. the method of operation was similar in both groups except for the amount of tenon sheath dissection. in the control group, the tenon sheath was cut 10 millimeters behind the insertion of the muscle and all the intramuscular connections were cut as much as possible. in the case group, the tenon capsule was cut 3-4 mm posterior to the location of the sutures over the recessed or resected muscles and intermuscular connections were left intact. results: fifty-four patients were enrolled in the study with 27 patients in each study group. there was no statistical difference between the two groups in terms of demographic variables. in both groups, the angle of strabismus was significantly reduced (p<0.05) postoperatively irrespective of the type of surgery. there was no significant difference between the two groups in terms of the corrected strabismus angle. after bmr, the angle of correction was 2.6±0.4 prism diopters per millimeter of muscle recession in the case group and 2.2±0.9 prism diopters per millimeter in the control group. after blr, the angle of strabismus was corrected by 2.3 ±0.2 prism diopters per millimeter of muscle recession in the case group and 2.2±0.2 prism diopters per millimeter in the control group. after r & r performed for esotropia, the angle of strabismus was corrected by 3.4 ±0.3 prism diopters per millimeter of muscle recession or resection in the case group and 3.2± 0.2 prism diopters per millimeter in the control group. after r & r for exotropia, the angle of strabismus correction was 3.1±0.5 prism diopters per millimeter of muscle recession or resection in the case group, and 2.7±0.3 prism diopters per millimeter in the control group. conclusion: the extent of the tenon dissection as well as cutting the intermuscular connections had no significant effect on the corrected strabismus angle. therefore, it is advisable to preserve the tenon capsule and intermuscular connections as mu