Sight-Threatening Graves' Ophthalmopathy during the Third Trimester of Pregnancy: A Case Report.

Dysthyroid optic neuropathy is a severe manifestation of Graves' ophthalmopathy that can result in permanent vision loss. We report a 37-year-old pregnant woman with Graves' ophthalmopathy which was deteriorated to dysthyroid optic neuropathy in the third trimester of pregnancy. Diplopia, bilateral eye lid retraction, lid edema and proptosis were observed in the 29th week of gestation. Thyroid-stimulating hormone (TSH) level was decreased with a normal level of free triiodothyronine (FT3) and an upper normal level of free thyroxine (FT4). Anti-TSH receptor antibodies (16.2 IU/L, reference range < 2.0 IU/L) and thyroid stimulating antibody (4,443%, reference range < 120%) were positive. Magnetic resonance imaging (MRI) demonstrated a significant enlargement of the extraocular muscles with a high signal intensity on T2-weighted image. She was diagnosed as Graves' ophthalmopathy and subclinical hyperthyroidism, and followed without treatment. In the 34th week of gestation, the symptom of color vision abnormality appeared, suggesting dysthyroid optic neuropathy. She delivered a female infant during the 36th week of gestation. Four days after delivery, she had a spontaneous orbital pain. MRI showed that the extraocular muscles were more enlarged than the findings in the 29th week of gestation. FT3 and FT4 levels were mildly elevated. Dysthyroid optic neuropathy was diagnosed. She was treated with methylprednisolone pulse therapy and retrobulbar injections of betamethasone valerate, and the ocular symptoms improved. The present case shows that the glucocorticoid therapy performed one week after delivery is effective against Graves' ophthalmopathy which was deteriorated to dysthyroid optic neuropathy during the third trimester of pregnancy.