Surgical Treatment of Diplopia in Graves Orbitopathy Patients.

Purpose: To review the authors' current understanding of motility dysfunction in patients with thyroid eye disease and to summarize appropriate evaluation and available management options.

Methods: Data were retrieved from a systematic search of the literature.

Results: Diplopia is one of the most disabling symptoms for Graves orbitopathy patients. It occurs in moderate-to-severe Graves orbitopathy stages and does not respond well to available anti-inflammatory treatment. Inflammation of extraocular muscles induces relatively rapid fibrotic and degenerative changes, which lead to scarring and loss of elasticity with preserved contractility. Inferior and medial rectus muscles are most often involved, which results in horizontal or vertical misalignment or both, and sometimes cyclotorsion. Impaired motility can also be caused by entrapment after orbital decompression. The aim of surgical correction is to restore/enlarge the field of binocular single vision and alleviate abnormal head posture. The basis for successful treatment is dependent on the identification of the involved muscles combined with the correct assessment of motility, misalignment, and binocular single vision.

Conclusions: Due to increased muscle tightness, recessions are the first choice of surgical procedures. Dosing is the most difficult part of the surgery. Several techniques are described: deviation-correction with preoperative determination of the dose, duction-correction either by active or passive intraoperative evaluation of ductions, and the application of adjustable sutures. Achievable success rates are comparable among these techniques but are dependent on the surgeon's experience. Cyclotorsion and misalignment after decompression and combined horizontal and vertical misalignments are more challenging to correct. Those types of deviations need special solutions like surgery on the oblique muscles and the usage of implants. The field of binocular single vision is the main outcome criteria for success, and the quantification may differ for research questions, study designs, and clinical purposes.