The vitreous is the transparent
jelly-like substance that fills the
space between the lens of the eye (inside the pupil) and the retina lining
the back of the eye. It is the simplest tissue of the body, since it
contains very few cells, no blood vessels, and 99% of its volume is water.
It is in contact with the retina and helps to keep it in place... (Schepens
Eye Institute /Harvard, US/; What is Vitreous Disease?)