CONICET | Buscador de Institutos y Recursos Humanos

Glaucoma is a leading cause of blindness, characterized by progressive loss of visual functions, retinal ganglion cell (RGCs) death and optic nerve head atrophy. Glaucoma has been conceived as a disease limited to the eye, but axons of RGCs have extraorbital and intracranial components. The aim was to study retinal projections in an experimental model of glaucoma in rats. Glaucoma was induced by weekly injections of chondroitin sulfate in the eye anterior chamber for 15 weeks. Visual pathway activity was analyzed through visual evoked potential recordings (VEPs), and major retinal projection areas (superior colliculus (SC), lateral geniculate nucleus and suprachiasmatic nuclei) through anterograde transport of cholera toxin β-subunit (CTB). In the glaucomatous visual pathway, the VEP N2-P2 component amplitude and transport of CTB from retina to all areas examined were significantly reduced, compared to vehicle. Furthermore, CTB was significantly accumulated in the optic nerves of glaucomatous eyes and glial immunoreactivity was significantly increased in the contralateral SC to glaucomatous eye. In sum, these results indicate that glaucoma induces significant alterations in extraocular visual pathway, and might cause trans-synaptic degeneration in retinal projection areas.