The influence of myopic refraction and intraocular pressure on the visual field in normal-tension glaucoma

In order to investigate the influence of myopic refractive error and intraocular pressure (IOP) on visual field defects in normal-tension glaucoma (NTG), the authors evaluated the relationship between the difference in the right and left eyes of 108 NTG patients regarding refractive error, axial length, and values for peak, trough, magnitude, and mean, during the 24-hour IOP diurnal variation. In 36 cases with emmetropia and hyperopia, the magnitude of IOP was significantly higher in the more damaged eye than in the less damaged one, and the side differences in mean deviation (MD) measured with the Humphrey Field Analyzer (HFA) between pairs of eyes revealed a significant correlation with values for peak, magnitude, and mean IOP. In 62 cases with moderate myopia, the trough of IOP was significantly higher in the more damaged eye, and the myopic refractive errors were significantly greater in the more damaged eye, and the side difference in MD between pairs of eyes showed a significant correlation with differences in trough IOP and axial length. These results suggest that both myopia and IOP may be associated with the progression of visual field defects in patients with NTG.