Selective ganglion cell death in glaucoma

The primate visual system is designed to provide maximum performance under a variety of conditions. Much of the enhanced sensitivity of the rod system comes from post-receptor neuronal organisation that pools impulses from thousands of receptors. In the retinal periphery multiple rods converge onto a single ganglion cell resulting in poor acuity but high sensitivity. At the fovea a one to one relation between cone and ganglion cell produces fine discrimination, colour perception and, by fusing the images of both eyes, binocular vision.

The “receptive field” for an individual ganglion cell is determined by the spatial arrangement of the connecting receptor fibres. These are designed to enhance perception of the stimulus and is achieved by an antagonistic arrangement of a concentric centre surround response where the surround is opposite in polarity to the centre.1

Ganglion cells have been subdivided according to their temporal response properties. Primate ganglion cells have been divided intotonic and phasictypes.2 Phasic cells respond transiently to changes in stimulus, while tonic ones provide a more sustained response. Phasic ganglion cells have both rod and cone input, make up about 10% of the total, and have large overlapping receptive fields. They subserve motion and contrast …