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Abstract #5955 Published in IGR 2-2
Selective ganglion cell death in glaucoma
Hitchings RABritish Journal of Ophthalmology 2000; 84: 678-679
This editorial starts with some background information on the primate visual system, receptive fields, and type of ganglion cells. The author discusses phasic and tonic ganglion cells and their size, and their connection to the magnocellular and parvocellular layers of the lateral geniculate body. The terminology of M cells and P cells has been used. The idea of separate visual functions based on different receptors and different post receptor organization has led to the concept of 'parallel visual processing'. The whole debate centers on whether M or P cells are preferentially lost in glaucoma. In the March issue of the British Journal of Ophthalmology, Morgan et al. further contributed to this debate. In six primate eyes, they found an overall reduction in mean size of both the surviving M and P cells, suggesting cell compromise before cell death. In any event, they do not seem to believe in the preferential loss of either system. The author states that selective death may still occur in early glaucoma, although alternative explanations are possible. This doubt regarding the mechanism does not remove the validity of selective psychophysical testing. The author ends by citing another study that corroborated earlier findings that ganglion cells with larger axons preferentially died in glaucoma. This issue has, of course, not yet been settled.
Dr. R.A. Hitchings, Moorfields Eye Hospital, London EC1V 2PD, UK
Classification:
1.3 Pathogenesis (Part of: 1 General aspects)
