Purpose: To investigate the dependence upon intraocular pressure (IOP) of the progression of visual field defects in eyes with primary open-angle glaucoma (POAG), in which the mean IOP was maintained at < or =21 mm Hg.
Methods: This study involved 100 eyes with POAG, which were followed up for > or =5 years. The mean IOP levels were maintained at < or =21 mm Hg during the follow-up period.