The pattern of glaucomatous optic disc cupping was investigated in 67 eyes of 67 primary open-angle glaucoma patients with early-to-moderate visual field loss and a wide range of intraocular pressure. We determined the position of the deepest point of the optic disc cup using the Rodenstock Analyzer. This position correlated significantly with intraocular pressure: the deepest point tended to be located below the center of the optic disc at high intraocular pressure and above the center at low intraocular pressure. There was no significant correlation between the position of the deepest cup point along the horizontal axis and intraocular pressure. The position of the deepest point of the cup also correlated significantly with the severity of glaucoma, albeit less strongly than with intraocular pressure: it tended to be in the inferior portion of the disc at an early stage of glaucoma and in the superior portion of the disc at a more advanced stage of glaucoma. Therefore, the inferior portion of the optic nerve head appears to be most yielding to changes of intraocular pressure. These findings are consistent with histologic evidence of the least connective tissue support in the inferoperipheral region of the lamina cribrosa and with greater prevalence of inferior rim loss and corresponding superior visual field defects in early to moderately advanced primary open-angle glaucoma patients.