Retina, detached: A retina that separates from its connection at the back of the eye. The process of retinal detachment is usually due to a tear (a rip) in the retina, which often happens when the vitreous gel pulls loose or separates from its attachment to the retina, most commonly along the outside edge of the eye. (The vitreous is a clear gel that fills most of the inside of the eye between the retina and the lens. If the retina is weak when the vitreous gel pulls loose, the retina will tear.) This rip is sometimes accompanied by bleeding if a blood vessel is also torn.
After the retina has torn, liquid from the vitreous gel passes through the tear and accumulates behind the retina. The buildup of fluid behind the retina is what separates (detaches) the retina from the back of the eye. As more of the liquid vitreous collects behind the retina, the extent of the retinal detachment can progress and involve the entire retina, leading to a total retinal detachment. A retinal detachment almost always affects only one eye. The second eye, however, must be checked thoroughly for any signs of the problem.
For a comprehensive article on this subject, please see Retinal Detachment: March 2000.