Scleral buckling surgery fails approximately 5% to 10% of the time because excessive scar tissue grows on the surface of the retina. This scar tissue is very bad for the eye. It pulls on the retina, causing it to redetach. Retinal redetachment usually occurs four to eight weeks after the initial surgery. The scar tissue also puckers the retina into stiff folds, like wrinkled aluminum foil. The vitreous also pulls on the retina, detaching it from the back wall of the eye. This condition is called proliferative vitreoretinopathy (PVR). The only way to unfold and reattach the retina is to cut away the vitreous and remove the scar tissue with vitrectomy surgery and then reattach the retina. The lens of the eye almost always has to be removed during the surgery. If an intraocular lens implant is in the eye, it can be left alone.
Removing the vitreous and especially the scar tissue from the surface of the retina is a delicate process that requires the surgeon to lift and peel strands of scar tissue away from the retina. The surgery may take many hours in severe cases. After the vitreous and the scar tissue are removed, an encircling scleral buckle is placed around the eye. The eye is then filled with air so that the retina is pushed against the back wall of the eye and against the scleral buckle. Once the retina is in place, laser is used to seal the retinal tears, and to form a strong attachment between the retina and the back wall of the eye. At this point, the surgeon may replace the air with a long-acting gas that remains in the eye for many weeks. The vision is always very poor when air or gas is in the eye. The gas keeps the retina pushed up against the eye wall long enough for the laser burns to heal and take hold. In some cases the same effect is achieved with clear silicone oil that is placed into the eye. If oil is placed into the eye, it is usually removed at a later time. Following surgery, it may sometimes be necessary for the patient’s head to be positioned in such a way as to help the gas seal the retinal tears. In some cases, extra injections of gas may be required after the surgery.
The chance of successful retinal reattachment with vitrectomy for PVR is about two out of three. The chance of regaining good enough vision just to get around is about 50%. Reading vision rarely returns. It should be clearly understood that the purpose of PVR surgery is to give the patient an eye that would have some vision and could serve as a "spare tire," if the other eye ever loses vision entirely.
It takes the vision a long time to completely recover after a vitrectomy. It is important to know that in some cases the scar tissue may reform after the surgery and cause redetachment of the retina.