Dysthyroid exophthalmopathy (orbitopathy) results from an enlargement of extraglobal orbital structures, producing ocular proptosis, optic nerve compression, and corneal exposure. Treatment with corticosteroids and radiation may be beneficial; refractory cases require surgical decompression of the orbit. Transantral orbital decompression was described by Walsh and Ogura and has been performed in over 350 patients at this institution. A review of 305 patients with long-term follow-up was performed. Visual acuity improved or was maintained at preoperative levels in over 95% of the patients, with ocular recession ranging from 1 to 12 mm (average: 4 mm). Postoperative ocular balance of relative exophthalmos was to within 1 mm in 76% of the patients and to within 2 mm in approximately 90% of the patients. Normal postoperative extraocular muscle balance was present in 99 patients. Immediate postoperative diplopia was noted in 206 patients. Long-term follow-up revealed that in 137 of these patients, diplopia resolved or responded to conservative management. Extraocular muscle surgery was required for correction in 69 patients. Twenty-seven patients had postoperative complications. These included 16 patients with hypesthesia of the infraorbital nerve, 5 patients with sinusitis, 3 patients who had incomplete decompression, 2 patients with oral antral fistulae, and 1 patient who had CSF rhinorrhea. Five patients, despite surgery, radiation, and steroid therapy progressed to blindness. We conclude that this procedure is effective and carries few complications. Orbital imaging, using computed tomography or magnetic resonance sequence with reconstructive capabilities, permits early diagnosis and treatment of dysthyroid compression optic neuropathy.