Retinal ganglion cell shrinkage in glaucoma.

SUMMARY: There has been some debate concerning the selective loss of retinal ganglion cells belonging to the magnocellular pathway in early glaucoma. Although histologic studies of retinal ganglion cells in experimental and human glaucoma have suggested selective loss of the larger cells and, by implication, selective damage to the magnocellular pathway, this has not been confirmed using psychophysical tests. Recent studies of retinal ganglion cell morphology in experimental glaucoma provide evidence that retinal ganglion cells undergo morphologic changes prior to cell death; cell volume is reduced in surviving cells with corresponding reductions in the size of the axon and dendritic tree. The magnitude of these changes is consistent with cell shrinkage as an explanation for the apparent selective damaged reported in earlier studies. It is also likely that widespread changes in the retinal ganglion cell population precede cell death, which will affect the physiologic behavior of these cells.