Retinal Detachment

Retinal Detachment Repair

The retina is a “Saran Wrap” thin membrane which is held to the inside
back portion of the eyeball by a kind of suction force. In the front part
of the eye the retina is firmly attached at a ring just behind the lens
called the pars plana. In the back part of the eye, the retina is
continuous with-the optic nerve-which carries 3 million nerve fibers
back to the brain. In between the pars plana and the optic nerve the
retina is attached by suction.

The interior portion of the eye is filled with a material called vitreous,
which is like a thin bag of jelly. As one gets older, the vitreous tends to
shrink, a process which is accelerated by prior cataract extraction or
being greatly nearsighted. The bag of vitreous is also attached firmly in
the front part of the eye at the pars plana. However, as the vitreous
shrinks, it ultimately strips itself free from the surface of the retina in
the back of the eye and begins to bobble around in the fluid. If it
happens that the vitreous was glued on too tightly at a single point or
several points just behind its firm attachment in the front part of the eye,
the hobbling of the vitreous jelly bag can tear the retina at these points.
Such a tear potentially breaks the suction holding the retina on.
Depending upon the strength of the suction force that holds the retina
on, the size of the tear, and the continued traction of the vitreous jelly
bag on the tip of the tear, the retina may detach.

In principle retinal detachments are fixed by finding all of the tears
and adequately closing them. It is both that simple and that complex!

There are two commonly used initial methods for repairing a detached
retina. One, pneumatic retinopexy, we will call the “bubble
procedure”. The other, scleral buckling, we will call the “buckle”.

Both procedures almost always are done as an outpatient under a local
anesthetic. The eye is made numb by injecting an anesthetic material
not into the eyeball, but rather in the orbit near the eye using a long, thin
needle. Often, a medication is given in a vein beforehand so that the
patient doesn’t care what happens next.

The bubble and the buckle both involve irritating the tissue around each
of the retinal tears. This is typically done by looking into the eye using
the indirect-ophthalmoscope .(that bright light on the surgeon’s
forehead) while pushing gently on the outside of the eye using a freezing
(cryopexy) probe. When a foot pedal is depressed, the tip of the probe
becomes very cold, producing a small area of freezing that involves the
retina and the tissues immediately underneath it. Using multiple small
freezes like this, each of the tears is surrounded. Irritated tissue forms a
scar once the retina is brought back into contact with the tissue
underneath it. This scars forms over the next 2 weeks or so. The
process is therefore a bit more like gluing furniture than welding. Both
the “bubble” and “buckle” are the same up to this point. After this, they
differ.

In the “bubble procedure” an injection of an expanding gas is made
into the back of the eye with a short;- very-skinny-needle: You the
patient are then asked to position yourself over the next 7-10 days in
such a manner that the bubble, rising in the fluid in the back of the eye,
plugs the tear(s). This reestablishes the suction, the fluid underneath the
retina reabsorbs, and the retina reattaches. After that, the bubble is used
like a splint, or, in the furniture gluing analogy mentioned above, like a
furniture clamp. You can readily see that if the tear that needs to be
closed is in the lower portion of the eye or if there are several tears
widely spaced apart, this procedure cannot be effective and is therefore
not offered.

When the eye wakes up, the bubble is seen as a shimmering surface
which is distinguishable from the retinal detachment by the fact that it is
always seen as being on the floor no matter which way the head is
moved. The bubble is reabsorbed by the blood stream and expelled
through the lungs as a natural process over the next 7-10 days.

The “bubble procedure” has the advantage that it produces only minimal
discomfort and the vision that will return tends to return quickly over a
matter of days to weeks. It has basically two disadvantages: one is the
need for positioning, which is mentioned above. Depending on the
location of the tear, this can be anything from a minor nuisance to a
major problem. Physical inability to maintain the position is one
contraindication to doing this procedure. Its other problem is that if one
takes all eyes to which the “bubble procedure” is applicable, the
procedure works only 7 or 8 out of 10 times. This does not mean that
the other 2 or 3 out of 10 eyes go blind. It usually means that these eyes
go on to scleral buckling, the other, more extensive procedure. Usually,
the need for scleral buckling is obvious within the first few days.

The “buckle” is performed in one of the operating theaters at the
outpatient Surgery Center. It begins with the anesthetic and freezing
treatment mentioned above. The tissues around the eye are then opened
using scissors so that access can be gained to the side of the eyeball. On
a spot or spots on the outside of the eye corresponding to where the tears
are on the inside, a piece a silicone rubber is sewn in such a way that
when the sutures are tightened up, the silicone indents the eye wall,
making a hill on the inside of the eye for the tear to rest on. Often, some
of the fluid under the retina is drained out of the eye using a fine needle
while the process is carefully monitored using the indirect
ophthalmoscope. The drainage and the indentation from the buckle
(usually close the breaks. This procedure has the advantage that it works
9 or 9 1/2 times out of 10 as a first procedure. It has the disadvantage
that it typically hurts considerably more, at least for the following day or
two, than does the “bubble procedure”. The vision that will return,
returns more slowly, typically over time measured in weeks or months.
The major advantage is that the “buckle” typically does not require any
special positioning. Furthermore, this procedure can be used to repair
retinal detachments to which the “bubble procedure” cannot be usefully
applied.

Pitfalls

The most common trouble with each of these procedures, the possibility
that in one operation the retina may not be attached, has already been
covered above. A subsequent attempt at repair can be entertained using
a combination of the procedures already mentioned or other techniques
that are available, but not covered here (e.g., vitrectomy). About 7 in a
100 eyes develop some generalized scarring referred to as PVR
(proliferative vitreoretinopathy) which shortens the retina, makes it less
elastic, and sometimes holds the breaks open despite efforts to close
them. Usually, some combination of techniques can be used to repair
retinas that develop this problem but sometimes, even with the best
efforts, PVR results in blindness.

Other risks include infection (either in the inside of the eye or of the
buckling element placed on the surface of the eye ball), perforation of the
eye with the anesthetic needle, bleeding, double vision, glaucoma, and
acceleration of cataract formation. All of these are quite uncommon,
but deserve mention.

All of this has been directed at reattaching the retina. Once the retina is
reattached, the process of visual improvement begins. In the case where
the center of the retina has not detached, the visual results are usually
quite good. When the center of the retina has been detached, the visual
results are less impressive, only rarely as good as the vision prior to the
detachment, but sometimes close to it.