MAGNOCELLULAR AND PARVOCELLULAR VISUAL PATHWAYS ARE BOTH AFFECTED IN A MACAQUE MONKEY MODEL OF GLAUCOMA

Purpose: Neurochemical changes in nerve cells were investigated in the lateral geniculate nucleus (LGN) and primary visual cortex of macaque monkeys with experimentally induced glaucoma. Methods: Glaucomatous d amage was induced in one eye of experimental animals by elevation of i ntraocular pressure following laser burns to the trabecular meshwork S taining for the metabolic marker cytochrome oxidase, as well as immuno labelling for the neuronal markers synaptophysin and neurofilament pro teins, was conducted on sections of the LGN and primary visual cortex. Results: In the LGN, staining for cytochrome oxidase and immunolabell ing for synaptophysin were reduced in the parvocellular and magnocellu lar layers that received input from the glaucomatous eye and neurofila ment protein labelling was reduced in the parvocellular layers. Cytoch rome oxidase staining demonstrated the presence of denervated ocular d ominance columns in layer IVC of the primary visual cortex of experime ntal animals. Conclusions: Pre-and post-synaptic neurochemical alterat ions in the magnocellular and parvocellular visual pathways of the bra in are associated with experimentally induced glaucoma in macaque monk eys.