If you think of the eye as a camera, the retina is like the film in the camera. It lines the back inside surface of the eye, and converts the optical image into nerve impulses that travel via a large nerve to the brain, where the impules become vision. The retina is only held in place against the wall of the eye by the pressure of the gel and fluid that fills the eye. This is like an inner tube held to the wall of a tire by the pressure of air. If a hole forms in the retina, the retina will deflate away from the wall of the eye, forming a retinal detachment. Holes in the retina occur for many reasons, but most are due to weak spots that occur for no identifiable reason. They are more common in nearsighted eyes. Detachments can also occur because of scar tissue pulling the retina forward, as often happens with diabetic retinopathy. Since the retina gets most of its blood supply from vessels in the wall of the eye, if it becomes detached, it does not get enough oxygen and cells in the retina suffer and begin to die. This is why most detachment repair operations are urgent. A major symptom associated with a tear or detachment is seeing flashing lights similar to lightning flashes in front of your eyes. Also, a shade or curtain may appear to block your vision. If holes in the retina are found before a detachment occurs, the holes can be sealed with a laser without invasive surgery. If detachment has recently started, repair may be possible with a procedure called pneumatic retinopexy. A gas bubble is injected into the eye and the patient is postioned so it floats up against the hole in the retina and pushes it back into place. Then a laser may be used to permanently seal it in place. For detachments that are more advanced, a surgical procedure may be required. This may be done by bending the wall of the eye in to meet the hole in the retina (scleral buckle procedure) or using very small instruments inside the eye to remove a scar pulling the retina forward (vitrectomy procedure). For some complex detachments, both may be combined in the same operation.
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