Low-tension glaucoma: a comparative study with retinal ischemic syndromes and anterior ischemic optic neuropathy.

In low-tension glaucoma (LTG), nerve-fiber-bundle defects are assumed to result from ischemia of the choroidal branches of the posterior ciliary arteries, due either to local vascular changes or, presumably, hemodynamically occlusive carotid artery disease. To study the possible hemodynamical origin of LTG, we examined and compared, clinically and by ultrasound (continuous-wave Doppler and duplex-scanning), the extracranial carotid arteries of (1) 21 patients (34 eyes) with LTG, (2) 48 patients (49 eyes) with retinal ischemic syndromes (RIS), and (3) 15 patients (17 eyes) with anterior ischemic optic neuropathy (AION). High-grade stenoses and occlusions of the internal carotid arteries ipsilateral to the affected eyes were significantly more frequent in the RIS patients (17 of 49) than in the LTG patients (2 of 34; P < .01) and the AION patients (0 of 17; P < .01). Among our relatively small group of LTG patients, we found no striking evidence supporting a hemodynamic origin of LTG.