We present a case report on a 53-year-old transsexual woman who developed acute painless vision loss in both eyes during cross-sex hormone treatment. After 10 months of cross-sex hormone treatment, she experienced total vision loss of the right eye and, 6 months later, vision loss to 20/63 in the left eye. After a full ophthalmic exam, bilateral sequential non-arteritic ischemic optic neuropathy (NA-ION) was diagnosed. Extensive etiological work-up revealed no cardiac abnormalities or inherited blood-clotting disorders. A manifest self-administered overdose of transdermal estrogen treatment with serum estradiol levels of 5,765 pg/ml was possibly related to the sequential bilateral NA-ION resulting in nearly total vision loss in this transsexual woman.