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The vitreous body plays an important role in the structure and in the function of the eye. Its bio-rheological properties contribute crucially to the mechanical resistance and optical transparency of ocular tissues. The composition and structure of the vitreous body change during aging and more rapidly in diabetes. These changes may have deleterious consequences such as functional disturbances and retinal detachment. The mechanical and optical properties of the vitreous are the result of its particular macromolecular architecture composed of a hyaluronan gel supported by a fine collagen meshwork, essentially of type II and IX. These are held together by proteoglycans and by fibronectin. All these macromolecules are susceptible to free radical damage produced by UV and visible light, by metabolic processes as well as the Maillard reaction. The mechanisms by which Maillard products and free radicals play a role in the physiological or accelerated aging of the vitreous are discussed in this review.