It is possible to reduce complications to less than 1 percent, says this
surgeon.
Paul Ernest, MD
Jackson, Mich.
If you frequently find yourself lying awake at night after rupturing a capsule,
thinking about what you should have done to prevent the problem, here's
some advice that may help you rest easier.
Using my math and engineering background, I developed
a systematic approach to cataract surgery that has helped me reduce the
rate of posterior capsule rupture in my practice from one in 500 to approximately
one in 1,000. Although my methods are obviously not going to be right for
every surgeon, I hope they will give you ideas for modifying yours.
1. Take responsibility
Many surgeons view complications as "acts of God" that just happen
no matter what the surgeon does. My research shows that in my OR, anyway,
the opposite is true. When I examined my surgical videos with a critical
eye, I found that I was consistently making small mistakes during my procedure.
The mistakes were not severe, and in the vast majority of cases they did
not result in capsular rupture. However, in difficult cases, when there
was poor patient cooperation, an imperfect capsulorhexis or when zonular
dialysis was present, these mistakes often made the difference between an
intact capsule and a ruptured one.
2. Keep your technique consistent
Several studies prove the existence of so called "muscle memory."
We execute complex muscular maneuvers based on instructions stored in the
spine and cerebellum that swing into action based on tactile feedback from
our fingertips. Research also shows, however, that performance declines
without constant training. The take-home message for surgeons is that we
will make fewer mistakes if we keep our technique exactly the same from
eye to eye. With rare exceptions, which I will discuss, do not alter your
cataract extraction technique for difficult cases. Instead, if at all possible,
alter the situation. For example, do not try to operate through a small
pupil. Widen the pupil instead.
3. Complete each step
You should always complete one step before moving onto the next. For example,
make sure you've achieved cortical cleavage before moving onto phacoemulsification.
If you don't, the nucleus won't rotate. If you try to force rotation, it
can lead to capsular tear.
4. Use the tools you need
The conventional wisdom is that we should try to use as few instruments
as possible in cataract surgery. Moving instruments in and out of the eye,
so this bromide goes, increases the risk of the tissue damage, and it's
more time consuming.
I no longer subscribe to this belief. There is no evidence that economizing
on instruments is beneficial in any way. And during my analysis, I discovered
that I often ran into trouble when I tried to press an instrument into double
duty. For example, as I'll discuss shortly, I now use two instruments to
do my capsulorhexis rather than just one.
5. Perform a careful capsulorhexis
In a large percentage of my cases in which I ruptured the capsule, my troubles
began because of a faulty capsulorhexis.
As a result, I no longer try to puncture the capsule by grasping it with
a forceps. Though this is the simplest method, it's not the most reproducible,
and it increases the risk that the tear will start drifting out into the
periphery and out of control.
I now use a 27-ga bent needle to create a triangular flap in the center
of the anterior capsule (Figure 1). Then, I switch to forceps and begin
my tear, pulling the flap in a counterclockwise direction each time. I never
try to complete the tear in one stepI found that this was consistently a
source of trouble. Instead, I tear until I reach 10 o'clock, then I stop
and regrasp the flap (Figure 2). I do this again to 7 and 4 o'clock and
then complete the capsulorhexis.
Before I release the capsule at each location, I place the torn capsule
in the center of the opening and then move forward. If you just release
the torn flap wherever you stop, it's possible for the viscoelastic to latch
onto it and drag the tear out into the periphery during aspiration.
6. Do complete hydrodissection
Rather than simply hydrodissecting, do hydrodissection-cortical cleaving
and hydrodelineation. In other words, fully separate the nucleus from the
cortex and the outer from the inner nucleus. This will greatly reduce the
risk of zonular damage and capsular tear.
I recommend the technique developed by Oregon cataract surgeon I. Howard
Fine. After making sure there is no air in the syringe, insert a 25-ga,
flat-tipped cannula under the anterior capsule at the mid periphery (Figure
3). As you're doing this, keep your thumb or finger off of the plunger so
that you don't inject the BSS too soon.
Once the cannula is in position, inject the fluid. It may seem strange,
but you'll know the cannula is in the right place if you don't see anything
happening. With successful cortical cleaving, there's a delayed reaction
as the fluid wave builds and comes around the nucleus and then pushes it
anteriorly. Once this occurs, stop injecting BSS and reposition the cannula
so that it's in the center of the nucleus. Then push down on the lens posteriorly
as you inject additional BSS into the center of the cataract. This will
separate the nucleus from the epinucleus. Finally, use the cannula to rotate
the nucleus. If it doesn't rotate easily, however, don't force it; you may
damage the zonules.
7. Watch your tip
How you remove the nucleus probably doesn't matter as much as using the
same technique each and every time. However, if you use John Shepherd's
divide-and-conquer method as a part of your technique, I recommend never
pushing the tip past the edge of the capsulorhexis (Figure 4). This reduces
the risk of creating tears in the anterior capsule that can then progress
posteriorly.
I also find that it works best to sculpt to a depth of 60 percent, or about
1 and 1/2 phaco tips. Once you've made your grooves, inject additional viscoelastic
(Figure 5) and use a pair of cracking forceps, preferably one with a large
surface area, to divide the nucleus into four quadrants. What's particularly
nice is that this technique works well with all types of nuclei.
8. Use "Smart" cortex removal
Often, surgeons make it through the entire procedure and then rupture the
capsule during this last step. Here are my recommendations for the removal
of cortex.
First, use a bimanual aspiration technique with two paracenteses to remove
residual cortex. This technique is commonly used in Europe, and the two-port
approach gives you access to all areas of the capsule.
Second, instead of attempting to strip the cortex right off the posterior
capsule, work to engage it just under the anterior edge of the capsulorhexis.
This offers a little more margin of error when the I/A tip latches onto
the capsule.
If you use a single handpiece to remove the subincisional cortex, first
inject additional viscoelastic and place the IOL. Next, use a right-angle,
blunt-tipped cannula with the aspiration port located on the underside (available
from Allergan), to strip off the remaining cortex, using the IOL as a barrier
to protect the capsule (Figure 6). Finally, switch back to the straight
aspiration cannula to remove the remaining viscoelastic under the IOL. To
do this, slip the cannula behind the IOL while you are in foot position
zero. Allow the IOL to come forward (Figure 7). Then go into foot position
one to deepen the chamber and then into foot position two to remove the
viscoelastic.
9. Have a game plan for abnormal eyes
As I mentioned earlier, it's important to remain consistent in the technique
you use. But in abnormal eyes, there are a few modifications that will help
reduce the risk of complications:
Posterior or polar cataracts. Avoid hydrodissection in these eyes. There's
often an adhesion between the capsule and the cataract. Hydrodissection
can cause a rupture in the capsule.
If a defect does occur as you lift the cataract off the capsule, perform
a limited vitrectomy and implant the IOL in the sulcus with the optic behind
the capsulorhexis.
Brunescent cataracts. Make the capsulorhexis larger than you normally
would, preferably at least 6 to 6.5 mm.
White or hypermature cataracts. Create the triangular flap with the
bent-tipped needle, wait for the
lens "milk" to come forward, and aspirate it out. Then fill the
anterior chamber completely with a dispersive viscoelastic and finish the
capsulorhexis. In these eyes, it's best to make the capsulorhexis smaller
than usual.
Zonular dialysis. If it extends less than three clock hours, I do
my standard technique. If it's a larger area, I prefer to use the Phaco
Flip technique developed by David Brown, MD, and then do an iris-plane phaco.
Small pupils. Enlarge the pupil prior to starting the case. My preference
is to use a bimanual stretching technique.
To do safer phaco and reduce your rate of complications, you don't need
to be a gifted surgeon. What you do need is discipline and the willingness
to think about what you're doing each step of the way. The good news is
that you don't have to sacrifice being an efficient surgeon to become a
safer one. I finish most of my cases in about 10 minutes.
Dr. Ernest is the founder of Eyecare Physicians of Michigan, which is now
known as TLC Eyecare of Michigan.
Figure 1. Instead of using forceps to start the capsulorhexis, use a bent-tipped
needle to create a triangular flap.
Figure 2. Once you've created the flap, switch to the forceps to create
the capsulorhexis.
Figure 3. For the best effect, begin hydrodissection-cortical cleaving by
placing a flat-tipped cannula under the anterior capsule at the mid periphery.
Figure 4. You'll reduce the possibility of creating a tear in the capsule
if you never extend the phaco tip beyond the capsulorhexis.
Figure 5. After creating the grooves, I always inject additional viscoelastic before I crack the nucleus into four pieces.
Figure 6. To remove subincisional cortex, I've found a 90-degree aspiration
tip works wonders.
Figure 7. At the very end of the case, I switch back to a straight-tipped
I/A cannula and slip it behind the IOL to completely remove the viscoelastic.
One Way to Handle a Capsular Tear by Robert M. Bernstein, MD Lewisburg,
Pa.
Despite our best efforts, every surgeon occasionally ruptures the posterior
capsule. The good news is that when you do, you can prevent vitreous loss
and all the attendant complications in about half the cases. Here's how.
When you first observe a capsular break, your adrenaline-generated impulse
is to remove the phaco tip from the eye. After all, the phaco tip is what
ruptured the capsule, so it makes sense to remove it immediately. But this
is exactly the wrong thing to do. By extracting the tip, you reduce the
pressure in the anterior chamber, and essentially vacuum the vitreous forward
through the capsular tear.
Remember, it's mostly what you don't do that counts. Do not pull the phaco
tip out; leave it in place. Then inject dispersive viscoelastic into the
area of the capsular tear and behind the remaining nucleus. (I personally
prefer to use Occucoat in these cases because it's easy to remove at the
end of the case and the remainder clears so well through the trabecular
meshwork. However, any dispersive viscoelastic will work.) The injected
viscoelastic will plug the front of the vitreous face, helping to keep vitreous
out of the bag and maintain a stable anterior chamber.
Leave the viscoelastic syringe in the side port incision and proceed with
phaco, continuing to inject viscoelastic as necessary to keep the vitreous
plugged and to maintain the chamber. It will be intuitively obvious at what
rate you need to titrate viscoelastic to maintain the chamber. Depending
on the stage of the case, you may need additional vials of viscoelastic.
Although the cost of the additional viscoelastic is significant, it's still
more economical then a vitrectomy.
Use very slow aspiration during cortical clean-up, as aggressive aspiration
could cause the vitreous to prolapse.
After placing the IOL in the capsular bag, I perform an iridotomy just in
case a vitreous strand makes its way into the bag and captures the pupil.
I then close as I normally would.
With this technique, I've found that I've avoided vitreous in at least half
of the cases where I've encountered a rupture in the posterior capsule.
Dr. Bernstein specializes in cataract surgery in his private practice.
April 1999 Review of Ophthalmology