We investigated the parameters that correlated with multiple defects in the retinal nerve fiber layer in 77 human eyes with normal-tension glaucoma, 110 with chronic high-tension glaucoma, and 102 control eyes. All 187 glaucomatous eyes had a nerve defect that was multiple in 20 cases. Correlation was significant between the multiple defect and the type of defect in the nerve fiber layer (P less than 0.002), size of the disc (P less than 0.02), and oblique insertion of the disc (P less than 0.02), as evaluated by the chi-square test. By multivariate analysis, refractive error was a high-ranking risk factor for multiple defect. Eyes with multiple defects tended to have moderate myopia, a focal nerve fiber layer defect and a small optic disc (category scores 0.0932, 0.0878 and 0.0697) and were less likely to have a diffuse defect in the nerve fiber layer, emmetropia or hyperopia, and a normal disc size (category scores -0.1077, -0.0705, and -0.548). The multiple defect in the retinal nerve fiber in glaucoma was frequently focal and correlated with myopia and a small optic disc.