Initial Postoperative Alignment in Strabismus Related to Thyroid Eye Disease

Postoperative drift and dose-response of strabismus surgery in thyroid eye disease: predicting desired outcomes with intraoperative adjustable sutures

OBJECTIVE

To report outcomes of strabismus surgery in thyroid eye disease using intraoperative bow-knot adjustable sutures under topical anaesthesia and calculate prediction models for surgical correction and postoperative drift depending on surgical dose-response.

METHODS

We retrospectively reviewed patients operated on from 2016 to 2021. A satisfactory outcome was defined as no diplopia with maintenance of vertical (<5 PD) and horizontal (<10 PD) stable alignment at primary gaze. Subjective diplopia corrected with prisms within successful motor alignment was defined as a fair result. Otherwise, the result was considered to be poor.

RESULTS

A total of 73 patients were included (60 females, 82%). Mean preoperative horizontal and vertical deviations were 26.9 PD (19.1 SD), and 11.8 PD (7.6 SD), respectively. Mean horizontal drift was -3.2 PD (5.2 SD), whereas mean vertical drift was -3.4 PD (3.3 SD). A linear regression established a dose-response of 2.37 PD/mm for each medial rectus recession (p < 0.0001; r2 = 0.777) and 3.75 PD/mm for unilateral inferior rectus recession (p < 0.0001; r2 = 0.922). Final success rate was satisfactory in 62 patients (85%), fair in 7 patients (10%), and poor in 4 patients (5%).

CONCLUSIONS

Muscle recession with intraoperative adjustable sutures is effective for the treatment of thyroid eye disease strabismus. Predictable dose-responses could be achieved with a drift toward overcorrection. Undercorrection proportional to the planned surgical dose should be the immediate postoperative target of choice. Other variables such as orbital decompression and concurrent vertical and horizontal surgery do not correlate with dose-response and postoperative drift. However, further studies are necessary to validate our findings.

Long-term follow-up of surgical treatment of thyroid-associated orbitopathy restrictive strabismus

OBJECTIVE

Thyroid-associated orbitopathy (TAO) is the most frequent cause of extraocular muscle enlargement, with consecutive restrictive strabismus. The main muscles involved are inferior and medial rectus, resulting in horizontal esotropia and/or vertical strabismus. Surgery may either establish or improve binocular single vision. The aim of the present study is to describe long-term follow-up of patients who underwent horizontal or vertical TAO strabismus surgery.

METHODS

This observational retrospective study included 29 patients suffering from either vertical or horizontal TAO strabismus and diplopia, of whom 11 underwent bilateral medial recti muscle recession (Group A) and 18 underwent unilateral inferior rectus muscle recession (Group B). The endpoint of the study was the assessment of changes in deviation angle and diplopia across four time points (baseline, 7 days, 6 months, and 24 months) in each group.

RESULTS

In Group A, the horizontal deviation angle significantly decreased 7 days after intervention (p < 0.001), without modifications overtime. In Group B, both deviation angles in primary and down-gaze position significantly decreased from baseline, both 7 days after surgery (p < 0.001) and at 6 months (p = 0.040). An overcorrection, with an inversion of vertical deviation angle, was observed across the different time points.

CONCLUSIONS

Horizontal TAO strabismus correction leads to significant improvements of deviation angle and diplopia, with a stable undercorrection overtime. Inferior rectus recession leads to more unstable results, with a trend towards overcorrection limited to the first 6 months after surgery.