Change in Proptosis Following Extraocular Muscle Recession in Thyroid-Related Orbitopathy

ABSTRACT

PURPOSE: To evaluate the effect of strabismus surgery on proptosis in thyroid-related orbitopathy METHODS: The medical records of 22 consecutive patients (38 eyes) undergoing strabismus surgery were reviewed. Data pertaining to number of muscles operated, the length of muscle recession, prior orbital decompression, and exophthalmometry (by either Hertel or Naugle devices) were evaluated. RESULTS: Thirty-eight eyes in 22 patients with thyroid-related orbitopathy were studied before and after the muscle surgery. The mean change in exophthalmometry for all eyes was an increase of 0.6 mm (p<0.01). Eyes with prior decompression averaged a 0.9 mm increase following strabismus surgery (p<0.01); those without decompression averaged a 0.2 mm decrease, although not statistically significant. For eyes with multiple muscles operated on a given eye averaged 1.2 mm increase; in those with one muscle operated the average increase was 0.2 mm. In cases where the inferior rectus muscle was operated on, the average increase was 0.9 mm. When the total length of muscle recession was less than or equal to 5 mm, the mean exophthalmometric change was a increase of 0.3 mm. If more than 5 mm, the mean was an increase of 0.8 mm. CONCLUSIONS: Strabismus surgery on patients with thyroid-related orbitopathy can worsen proptosis, especially those with prior decompression. When planning for orbital decompression, the surgeon should consider this effect. Patients should be made aware of possible changes to their appearance.