A vitreous hemorrhage is bleeding inside the eye, which can sometimes lead to significant vision loss. 

 

Typically, the bleeding results from rupture of blood vessels in the retina or other structures inside the eye.  Some common causes include diabetes, posterior vitreous detachment (a separation of the jelly inside the eye from the retina), trauma, retinal tear, retinal vascular occlusions, certain blood diseases, and blood thinner use.