Compartmental Strabismus

Advancement of the muscle insertion toward the limbus as an alternative or adjunct to resection

PURPOSE

To describe the surgical outcomes of patients that underwent strabismus surgery involving advancement of the muscular insertion line toward the limbus.

METHODS

The medical records of patients who underwent rectus muscle advancement surgery between January 2009 and June 2019 and had at least 1 year of follow-up were reviewed retrospectively. Patients were classified into one of four types of deviation: (1) convergence insufficiency, without distance deviation; (2) small-angle distance esotropia, with diplopia; (3) residual strabismus after previous surgery; and (4) large-angle exotropia. The first group underwent 2 mm advancement of the medial rectus insertion bilaterally; the second, 2-3 mm advancement of the lateral rectus muscle bilaterally; the third, 2-3 mm advancement of the lateral or medial rectus muscle, with or without simultaneous resection; and the fourth, 3 mm advancement of the medial rectus with simultaneous resection, with or after maximum recession of the lateral rectus, bilaterally or unilaterally.

RESULTS

A total of 25 patients were included (mean age, 28.76 ± 22.75 years): 4 with convergence insufficiency, 3 with small-angle distance esotropia and diplopia, 16 with residual strabismus, and 2 with large-angle exotropia. Mean postoperative follow-up was 4.76 ± 2.03 years. Surgery was successful in all patients at 1 year (residual deviation ≤10^Δ), and all but 1 at 5 years; 1 patient required reoperation.

CONCLUSIONS

Advancement of the muscle insertion proved successful as an alternative or adjunctive procedure to other forms of muscle tightening in the subtypes of patients evaluated in this study.

Strabismus surgery outcomes for internuclear ophthalmoplegia with exotropia

Exotropia (XT) in internuclear ophthalmoplegia (INO) is a difficult problem to treat. The purpose of this study is to describe surgical approaches in treating INO and glean insight into various pre-operative factors that may affect outcomes for XT in INO. We conducted a retrospective review from 1 January 1995 - 5 January 2021 and identified seven patients with INO who underwent strabismus surgery for XT. Patient age, sex, etiology of INO, pre-operative alignment and sensorimotor exam, presence of diplopia, surgery performed, subsequent surgeries, use of adjustable sutures, post-operative alignment, presence of post-operative diplopia, presence of post-operative diplopia with use of prism correction, and length of follow-up were all collected. Initial surgeries undertaken included unilateral medial rectus (MR) plication and lateral rectus (LR) recession, bilateral medial rectus (MR) plications or resections, or bilateral MR plications combined with either unilateral or bilateral LR recessions. Chart review yielded ten charts, however two were excluded due to manifest esotropia (ET), and one was excluded due to incomplete records. Seven total patients were used in final analysis. The cohort age range was from 29 to 79 years. Pre-operative horizontal distance alignment ranged from 35 to 95 XT with an average exodeviation of 67.8 ± 22.6 prism diopters (PD). Horizontal adduction deficit ranged from -1 to -4 and was present bilaterally in all patients. A variety of initial surgical approaches were undertaken. After two muscle surgeries, distance deviation had an average change of 57.3 PD. After three muscle surgeries, distance deviation had an average change of 75 PD. After four muscle surgeries, distance deviation had an average change of 60 PD. Three patients required additional surgery for XT. Time to follow-up ranged from 1 to 58 months. Horizontal distance alignment in primary gaze at latest follow-up ranged from 30 ET to 30 XT with an average of 0 (orthotropia) ± 16.0 PD. One patient had a consecutive esotropia of 30 PD, one had a persistent exotropia of 30 PD, and five patients were orthotropic at distance. All patients reported relief of diplopia in primary gaze at near and distance either with or without use of prism. Horizontal ductions improved to some degree in all patients. Horizontal rectus surgery can treat many cases of XT in INO. Surgeons should consider INO etiology and concomitant vertical deviations when considering surgery. The degree of pre-operative adduction limitation is another important factor, though did not always dictate final motor and sensory outcomes.

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

Purpose

To evaluate the efficacy and safety of slanted bilateral lateral rectus recession (S-BLRc) for the treatment of convergence insufficiency-type intermittent exotropia (CI-IXT) in children and to probe the relationship of the slanted amount and surgical outcomes.

Methods

Retrospective study. Fifty-eight patients with CI-IXT, aged 4 to 10 years old, underwent S-BLRc procedures. According to the different slanted amount between the upper and lower poles of lateral rectus, all the patients were grouped: Group A (slanting 1 mm, n = 22), Group B (slanting 1.5 mm, n = 18) and Group C (slanting 2 mm, n = 18). The successful surgical outcome was defined as deviation in the primary position ranging from exotropia< 8^△ to esotropia< 5^△ both at near and at distant as well as the near-distance difference (NDD) < 5^△. We analyzed and compared the preoperative and postoperative data including deviations both at near and at distance, NDD, objective torsion, horizontal deviation at up and down gaze, lateral incomitance, binocular vision and surgical success rate among three groups.

Results

The average deviations were significantly decreased from − 37.1^△ ± 4.2^△ (−,exotropia) to − 1.4^△ ± 4.6^△ at near (P < 0.05) and from − 25.8^△ ± 3.7^△ to − 0.1 ± 4.1^△ at distance (P < 0.05). The postoperative NDD on average was significantly reduced from 10.0^△ to 1.8^△ in Group A (P < 0.05), from 11.2^△ to 0.8^△ in Group B (P < 0.05) and from 13.3^△ to 0.9^△ in Group C (P < 0.05). There was a significant difference in the mean corrections of NDD among the three groups (8.2^△ in group A, 10.3^△ in group B and 12.4^△ in group C respectively, P < 0,05). All the patients attained various improvement of stereopsis after surgery. None had torsional diplopia, A-V pattern and lateral incomitance after strabismic surgery. Totally, the surgical success rate was 89.7% in our series at the 6- to 8-month follow-up.

Conclusions

Slanted bilateral lateral rectus recession is an effective and safe procedure for the treatment of CI-IXT in children. S-BLRc can successfully collapse exotropia both at distance and at near, decrease NDD and benefit to gain binocular vision. The correction of NDD was associated with the slanted amount.