Visual postural performance in ametropia and with optical distortion produced by bifocals and multifocals

Visual stabilization of posture depends strongly on the performance of the visual system and declines with experimentally induced reduction of visual image quality. We studied postural performance in subjects with median and high grade hyperopia or myopia. While body sway of median grade ametropic subjects increased slightly when measured without glasses, high grade ametropia showed no significant differences between postural performance with glasses on and off. We concluded that the increase in visual acuity when wearing glasses is outweighted by concurrent dioptric distortions such as size change and prismatic effects. In addition we could not find any difference between bifocal and multifocal lenses in their effect on sway when investigated in normals with either steady fixation or saccades or foveal pursuit.