Effect of bimedial recession on near-distance disparity in esotropia.

Background: Esotropia may be associated with a difference in the deviation at near and distance fixation termed near-distance disparity (NDD). Convention suggests patients with NDD may benefit more from bilateral medial rectus recessions (BMR) as opposed to a unilateral recession/resection (RR). The aim of this study is to establish the effect of BMR for the treatment of esotropia on both the near and distance deviation and NDD.

Methods: Retrospective patient records search from 2011 to 2021.

Inclusion Criteria: comitant esotropia, first surgery, equal and normal vision with free alternation.

Exclusion Criteria: incomitant, neurological or restrictive strabismus, previous surgery, clinically significant amblyopia.

Results: 49 patients met the inclusion criteria. 19 patients were female; the average age was 17 years. Following surgery, the average near deviation reduced from 39PD base out (BO) to 11PD BO. The average distance deviation reduced from 33PD to 9PD. Average preoperative NDD was 12 PD. NDD resolved in 15 out of 18 patients with NDD (83%). The average PD gain per mm of recession was 2.7 for near and 2.2 for distance.

Conclusions: BMR is an effective surgical treatment for esotropia and has a greater effect on near deviation than distance. It is also an effective and simple technique for lesser degrees of NDD. BMR has several advantages over RR: no tissue loss, readily reversible, the scars are easier to hide and it avoids potential motility limitations due to leash effects following resection.