Vascular compression of the optic chiasm resembling glaucoma-like visual field defects.

• Vol 7 • October 2005 Normal-Tension Glaucoma Open-angle glaucoma with normal intraocular pressure, also known as normal-tension glaucoma, is estimated to constitute 10–25% of all glaucoma cases. NTG is a diagnostic challenge, as various lesions affecting the visual pathways including compression by normal or abnormal intracranial blood vessels can mimic its clinical findings. In recent years, several studies have shown a statistically significant percentage of patients with NTG who were shown to have compression of the optic nerves by normal or abnormal carotid arteries compared with controls or patients with high pressure glaucoma. We report two patients who initially presented with clinical signs imitating bilateral NTG, with non-progressive binasal visual field defects due to optic chiasm compression by low positioned anterior cerebral arteries. We show the radiologic findings and discuss possible explanations for these observations.