Dysthyroid optic neuropathy (DON).

Dysthyroid Optic Neuropathy (DON) affects a small percentage of patients with Graves disease, but, when it occurs, it can cause significant and permanent loss of vision. DON is treatable if recognized early. Systemic steroids can be effective, but may cause side affects. Orbital injection of steroids may play a role in selected patients. Orbital radiation has a more permanent effect and has gained wide acceptance as a relatively non-invasive method of reversing DON. Surgery to decompress crowded orbits has been used for years and continues to be a viable approach for those patients with optic neuropathy, especially when there is significant proptosis. Optic nerve decompression can also be achieved through a transethmoidal approach.