DETACHED RETINA

eye disorder involving separation of most layers of the retina, the light-sensitive layer of tissue that lines the back and sides of the eye, from the choroid, the pigmented middle layer of the eyeball. As a person ages, small tears can develop in the retina, through which vitreous humour (the jellylike substance in the eye) leaks. This causes the retina to peel away from the choroid. Retinal detachment usually occurs only in persons who are middle-aged or older (an exception is the disease retrolental fibroplasia, q.v.), and it is more common in individuals who are nearsighted. The detachment also may result from a physical accident. The separation usually develops slowly and does not cause pain. A person typically will describe seeing floating black spots and flashes of light in the affected eye, and vision will become progressively more blurred. Restoration of the retina to its normal position is achieved by draining the fluid from behind it and applying heat, a laser beam, or extreme cold to the wall of the eye. The resultant scar tissue that forms seals the tears and prevents the retina from detaching again. If the retina is not reattached soon enough, the affected eye becomes permanently blinded.