In the study, a total of 163 patients with a Graves' hyperthyroidism diagnosis received either radioactive iodine treatment, or 18 months of medical treatment. The researchers found that development of thyroid eye disease, and worsening of existing thyroid eye problems, were significantly more common in the patients received radioactive iodine treatment.
Overall, the researchers also found that new onset of thyroid eye disease was a greater risk in those patients who had the radioactive iodine, versus other treatments.
And for the patients, smoking was the greatest risk factor of all for thyroid eye disease. Smokers who had RAI had had the highest risk of thyroid eye disease.
Träisk, Frank et. al. "Thyroid-Associated Ophthalmopathy after Treatment for Graves' Hyperthyroidism with Antithyroid Drugs or Iodine-131" Journal of Clinical Endocrinology & Metabolism, 2009;94:3700-3707. Online