Variability Between Changes in Ocular Alignment and Gorman Diplopia Score After Teprotumumab in Thyroid Eye Disease

Diplopia in thyroid eye disease (TED) results from restrictive myopathy and can be disabling. Teprotumumab, an insulin-like growth factor-1 (IGF-1) antagonist, reduces proptosis and improves diplopia as measured by a subjective Gorman diplopia score without assessing ocular misalignment. This study evaluated whether there was observed variability between subjective versus objective measures of diplopia assessment in patients with TED treated with teprotumumab. This retrospective case series included patients with TED-related diplopia treated with teprotumumab at a single institution. Gorman diplopia scores and strabismus measurements in primary and cardinal gaze positions were recorded before and after treatment. Patients without diplopia, with unrelated strabismus, or with <3 months of post-treatment follow-up were excluded. The primary endpoint was change in ocular alignment and Gorman score before and after teprotumumab and the secondary endpoint was examining the difference between the two outcomes of diplopia assessment. Of 67 patients treated, 17 met inclusion criteria. Teprotumumab improved ocular alignment in 71% (12/17) and Gorman score in 59% (10/17). Changes in alignment and Gorman score were not in alignment in 41% (7/17): 12% (2/17) showed Gorman improvement despite worsened alignment, while 30% (5/17) had alignment improvement without change in Gorman score. Teprotumumab improves both ocular alignment and diplopia in most TED patients; however, differences were observed between subjective and objective outcome measures. Validated tools are needed to assess therapeutic outcomes more accurately in TED-related strabismus.