To assess glaucomatous damage to the lateral geniculate nucleus of the thalamus, as well as to its magnocellular and parvocellular layers, we examined the autopsy sections of the lateral geniculate nucleus of individuals with and without glaucoma. Five patients with a documented history of glaucoma and five controls with no ophthalmic or chronic central nervous system disease were included in this study. Neurons were counted in autopsy sections of the lateral geniculate nucleus. Cells were counted in 40 random microscopic fields of the magnocellular and parvocellular layers respectively. The mean magnocellular cell density for the glaucoma group of 2.72 +/- 0.13 cells per square millimeter (mean +/- SEM) was significantly less than that for the control group of 3.76 +/- 0.13 cells per square millimeter (P < .001). There was no statistical difference in the parvocellular layer. These data suggest that glaucoma leads to greater loss of magnocellular tissue at the level of the lateral geniculate.