Slanted recession on bilateral lateral rectus for the treatment of intermittent Exotropia with convergence insufficiency

Surgical outcomes and etiological considerations in intermittent exotropia: a systematic narrative review

Introduction: Is Intermittent Exotropia being conceived and treated as an ocular-mechanical problem? Is etiology taken into account when planning for intervention? Which success criteria are used? Are they based on alignment or do they also consider visual function? In order to answer these questions, a review of studies assessing the outcomes of strabismus surgery in Intermittent Exotropia has been conducted. Methods: published between January 2003 and December 2023 were included. The database searched was MEDLINE following a predefined protocol. In addition to electronic database searches, manual searches were carried out and experts contacted. A total of 102 studies comprising 12 974 participants were included in this review. Results: Possible strabismus etiology was not stated in 91.2% of the studies. The underlying causes of the deviation were not taken into account for treatment consideration in any of the studies. Criteria for surgical success was based solely on ocular alignment (82.4%) and only 10 studies (9.8%) defined successful surgery with both motor and sensory criteria. Thirty-four different definitions of successful ocular alignment were identified. Discussion: In conclusion, Intermittent exotropia etiology is omitted in studies assessing surgical outcomes. The possible causes of the deviation are not taken into account when deciding on the type of surgery and are rarely mentioned. In most studies, the criteria for surgical success is based solely on eye alignment, independently of visual function and control.

Slanted and Standard Lateral Rectus Recession Procedures for Convergence Insufficiency-Type Intermittent Exotropia in Children: A Retrospective Cohort Study

Purpose

To evaluate the efficacy and safety of slanted bilateral lateral rectus recession (BLR-rec) for treating convergence insufficiency-type intermittent exotropia (CI-IXT) in children.

Methods

In this retrospective cohort study, 26 patients aged <16 years with CI-IXT who underwent BLR-rec between August 2016 and July 2021 with six months of follow-up data post-surgery were classified into slanted BLR-rec group (n = 14) and standard BLR-rec group (n = 12; equal-length recession of the upper and lower horns of the LR muscle). Surgical outcomes were compared between the groups.

Results

In the slanted and standard groups, the preoperative distance exodeviation was 27.9 ± 5.5 and 30.8 ± 10.0 prism diopter (PD) (p = 0.63), near exodeviation was 41.1 ± 5.6 and 42.9 ± 9.2 PD (p = 0.75), and difference between near and distance deviation (N-D deviation difference) was 13.2 ± 3.2 and 12.1 ± 3.3 PD (p = 0.30), respectively. The ratio of postoperative and preoperative N-D deviation difference was compared between the slanted BLR and standard BLR groups at six months postoperatively. The results revealed that the ratio for slanted-BLR was 0.44 ± 0.19, and for standard-BLR was 0.84 ± 0.24. In the standard group, stereoacuity remained unchanged post-surgery compared to that pre-surgery, while the slanted group showed significant improvement (p < 0.05, Wilcoxon signed-rank test).

Conclusion

Compared with the standard BLR-rec procedure, the slanted BLR-rec procedure reduced N-D deviation differences in CI-IXT, positively impacting gross stereopsis.

Medial Rectus Inferior Half Plication for the Treatment of Near Exotropia

PURPOSE

To report a relatively new surgical treatment for near exotropia called medial rectus inferior half plication.

METHODS

This was a retrospective analysis of the outcomes from a single surgeon performing a plication of the inferior half of the medial rectus muscle in 17 consecutive patients with near exotropia unresponsive to medial rectus bupivacaine injection.

RESULTS

Thirteen of 17 (76%) patients were asymptomatic after surgery with no diplopia for near fixation and with either a normal or slightly reduced prism fusion range enabling them to have comfortable binocular single vision. There was one minor surgical overcorrection with distance diplopia that disappeared within 2 weeks of surgery. Of the 4 of 17 (24%) patients who required further intervention, 3 required one further surgical procedure and 1 required an injection of bupivacaine into the contralateral medial rectus muscle to obtain a satisfactory alignment and control of symptoms. No patient needed more than two total operations.

CONCLUSIONS

The data show medial rectus inferior plication can produce excellent outcomes with minimal risk of overcorrection. [J Pediatr Ophthalmol Strabismus. 2024;61(3):219-222.].

Effects of slanted bilateral lateral recession vs conventional bilateral lateral recession on convergence insufficiency intermittent exotropia: a prospective study

AIM

To observe the surgical effects of slanted bilateral lateral recession (S-BLR) versus conventional bilateral lateral recession (C-BLR) in convergence insufficiency intermittent exotropia (CI-IXT).

METHODS

Using a randomized, double-blind, prospective design, 22 patients with CI-IXT who were admitted to Renmin Hospital of Wuhan University from July 2019 to December 2020 were included. Patients were randomly divided into either S-BLR or C-BLR group for their subsequent strabismus surgery. All patients were followed up for 12mo. Near deviation, distant deviation, and near-distance difference (NDD) were measured in all patients.

RESULTS

Twelve months after surgery, NDD improvement was 10 (8, 13) prismatic degrees (PD) in S-BLR group and 3 (1, 6) PD in C-BLR group (P=0.011). The near deviation of S-BLR group was 0 (-2, 2) PD, while that of C-BLR group was -4 (-6, -3) PD (P=0.005). Before and after surgery, the difference in the distant deviation between the two groups was not statistically significant. There was no statistically significant difference in near stereopsis between the two groups (P=0.380) at 12mo. The success rate at 12mo after operation was 90.91% and 72.73% in the two groups (P=0.280).

CONCLUSION

CI-IXT patients treated with S-BLR have better surgical outcomes than those treated with C-BLR, which indicates S-BLR is a safe and effective operation pattern.