We have investigated the effect of glucosamine on the retinal cells after continuous infusion into cerebroventricle by using osmotic minipump to avoid peripheral effect. Continuous intracerebroventricular (i.c.v) infusion of glucosamine with the rate of 0.1 μmol/10 μl/hr for 7 days resulted in morphological changes of the optic nerve in electron microscopic level as well as morphological changes of the retina in light microscopic level. Retinal sections were immunostained for the detection of morphological changes of astrocytes. GFAP immunoreactivity appeared not only in the Muller cells but also many of the radial processes of Muller cells. The optic nerve showed deformed axon and slight lamellar separation of myelin sheath after continuous infusion of glucosamine in observing with electron microscope. Interestingly, vacuoles were observed in deformed axons and retinal layers were folded and detached. These results suggested that glucosamine plays a role in induction of morphological dysfunction in retina and optic nerves.