Scleral buckling surgery fails approximately 5% to 10% of the
time because excessive scar tissue grows on the surface of the
retina. The scar tissue 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 vitrous and remove the
scar tissue with vitrectomy surgery and then reattach the retina.
The lens of the eye almost always have to be removed during the
surgery. If an intraocular lens implant is in the eye, it can
usually be left in position.
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 will replace the air with a long-acting gas. The gas
remains in the eye for many weeks before it is naturally absorbed.
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 three out of four. 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