What is the role of botulinum toxin in the treatment of dysthyroid strabismus?

Management of Thyroid Eye Disease-Related Strabismus

Purpose:

To review various treatment methods in thyroid eye disease (TED) related strabismus.

Methods:

We searched in PubMed and Google Scholar and Ovid MEDLINE for keywords including TED-related strabismus, strabismus in thyroid-associated ophthalmopathy, Graves^' ophthalmopathy related strabismus or squint, and restrictive strabismus. Two expert strabismus specialists selected and evaluated the English articles that were related to our paper and had been published since 2000. Some articles were added based upon the references of the initial articles.

Results:

One hundred fifteen articles were found, 98 of which were mostly related to the topic of this review. Management of TED-related strabismus was reviewed and categorized in non-surgical and surgical. Botulinum toxin A (BTA) is a useful non-surgical management of strabismus in an active TED and residual deviation after strabismus surgery. Postoperative under-correction is relatively more common in TED-related esotropia. Lateral rectus resection and BTA are the options to manage the problem. Muscle rectus muscle resection should be performed after maximum recession of restricted muscles. It should be avoided on a restricted or enlarged muscle. Management of TED-related vertical deviation is challenging. In these cases, the surgical treatment selected depends on forced duction test (FDT) (pre and intraoperative), orbital imaging (which muscle is enlarged), and the amount of vertical deviation (in both down-gaze and primary position).

Conclusions:

TED-related strabismus needs careful evaluation and management to achieve optimal outcome. Different surgical and non-surgical options are available for intervention in TED-related strabismus.

[Surgical management of strabismus in dysthyroid orbitopathy: A retrospective single-center study of 32 cases]

INTRODUCTION

Thyroid-related immune orbitopathy often results in a restrictive strabismus. We report our experience of surgical management in these cases.

PATIENTS AND METHODS

We present a retrospective case series conducted on 32 patients, operated between 2008 and 2017. Strabismus surgery was proposed in the postinflammatory stage with stable clinical findings for at least 6 months. It was performed under general anesthesia by recessions of restrictive muscles using a fixed suture technique. Outcomes were graded as excellent, good or poor, according to the presence or absence of diplopia in primary or reading positions, and according to whether prism prescription was necessary.

RESULTS

The study included 32 patients (21 women, 11 men) with a mean age of 53 years. Average follow-up was 9.6 months. Eight patients developed diplopia after orbital decompression. Fifteen patients had vertical surgery, 8 horizontal surgery, 9 mixed surgery. A mean of 1.31 surgeries (range 1-3) were performed. After all surgeries, 28 patients (87.5 %) had an excellent outcome, 4 (12.5 %) had a good outcome, and none had a poor outcome. There was a significant improvement in stereoscopic acuity (P<0.01), but not motility. Among the 8 patients who developed diplopia after orbital decompression, a clinically acceptable final outcome was achieved after only one surgery.

CONCLUSION

Strabismus surgery using conventional non-adjustable sutures provides excellent ocular alignment and relief from diplopia in the majority of patients with dysthyroid strabismus. The reoperation rate is similar to other techniques, such adjustable suture and intraoperative relaxed muscle technique.

The clinicopathologic basis of Graves' ophthalmopathy: a review

PURPOSE

Graves' ophthalmopathy (GO) is a controversial disease, with disagreement within the medical community regarding its pathogenesis, diagnosis, and treatment.

METHODS

We reviewed recent literature on clinical and pathological aspects of GO from both the endocrinologist's and ophthalmologist's perspective.

RESULTS

Investigations into the pathogenesis of GO have included possible antigenic targets, orbital cell types, and development of animal models. Diagnosis has been improved recently with new tools and grading systems, but can be complicated by conditions that may simulate one or more of the findings of GO. The new findings of clinical studies also compel practitioners to reassess commonly used GO treatments such as orbital irradiation.

CONCLUSIONS

Improved understanding of the pathogenic mechanisms of GO should hopefully lead to new diagnostic and therapeutic approaches to this problematic condition.

Eye muscle surgery

In the past year experimental studies have analyzed the ease with which specific sutures can be adjusted, have investigated ways to prevent adhesions in animal models, and have studied variations of the inferior oblique at the surgical capture site. Our knowledge of rectus extraocular muscle pulleys continues to improve, and the value of botulinum toxin type A in the treatment of several conditions has been further documented. New surgical techniques include slanted recessions of the lateral rectus muscles, combined monocular resection and bilateral anterior transposition of the inferior oblique, and intraoperative use of acetylcholine during inferior oblique myectomy. Favorable results have been reported after clinically important modifications to the superior oblique muscle silicone expander and anterior transposition of the inferior oblique procedures, as well as after bilateral inferior rectus muscle recession in dysthyroid ophthalmopathy. Conjunctival inclusion cysts, anterior segment ischemia despite microvascular dissection, and corneal topographic changes are reported as complications occurring after strabismus surgery. Recent publications discussing these issues are reviewed here.