Every surgeon can expect one, but anticipation and
preparation can make
a rupture in the posterior capsule a
manageable crisis.
Recognize it. Stop. Stabilize it.
These are three keys to catching a small posterior capsular rupture
before it becomes a larger rupture, and a much more complicated
case.
“All cataract surgeons will get a rupture, and hope is
not a good strategy,” said Randall J. Olson, MD. Following are some
approaches offered by Dr. Olson and other experts for dealing with
breaks in the posterior capsule during cataract surgery.
Recognize
It
First, prevention is always better than
treatment. “The best of practices have a rupture rate in the range
of two to four per thousand cases. It can be that low,” Dr. Olson
said. “If I’ve had four in the last 200 cases, or 2 percent, I have
to ask, ‘What can I do to get it lower?’”
Use techniques that
keep you away from the capsule, Dr. Olson suggested, and keep a log
of your capsular ruptures. “Videotape them, and review the tapes. By
recognizing those steps that led to a rupture, you can change your
technique to avoid it,” he said.
In this way, Dr. Olson discovered that his most common rupture
occurred while polishing the posterior capsule with an
irrigation-aspiration tip in which he finds a barb. “Something
abnormal was occurring during autoclaving,” he explained. “That has
changed my whole thought process.”
You can also lower your
rupture rate by using the newer-generation phaco systems (such as
the AMO Sovereign, Alcon Infiniti and Bausch & Lomb Millennium),
which provide improved fluidic surge protection, said R. Bruce
Wallace III, MD.
Stop and
Stabilize
When you suspect a tear in the
posterior capsule, immediately stop all aspiration and ultrasound.
Keep the infusion on and the phaco or I&A tip still, advised
Jack A. Singer, MD. Do not use the irrigating tip to move things out
of the way. “Even if you are just irrigating, a small amount of flow
may be coming up the tip. I take my second instrument to clear away
and take a look at that area,” Dr. Olson said.
Once you
confirm a rupture, keep irrigating (but not aspirating). “Go through
your side-port incision, and start right down on the rupture putting
dispersive viscoelastic to tamponade and reinforce that area, to
push everything out of the way. Fill the anterior chamber and give a
bolus of viscoelastic as you come out of the eye. This maintains a
deep anterior chamber, and no positive net flow from vitreous moving
forward,” Dr. Olson said.
In the setting of a ruptured
posterior capsule, it is advisable to use a dispersive ophthalmic
viscoelastic, such as Viscoat (Alcon) or Vitrax (AMO), said David F.
Chang, MD. “These agents tend to resist aspiration and are less
easily burped out of the eye,” he explained. “When left behind in
the posterior segment, these agents should cause fewer problems with
postoperative IOP than a cohesive viscoelastic would.”
Choose Your
Surgical Strategy
When you have a stable
situation, with the chamber full of dispersive viscoelastic, Dr.
Olson said, take a minute to look and decide your next step. Your
surgical strategy depends on the severity of the
rupture.
Posterior capsulorhexis. If no
vitreous was aspirated, and the rupture is very small and clearly
visible with no large linear extensions, try to convert it into a
posterior capsulorhexis. “A posterior capsulorhexis is a little
trickier than an anterior capsulorhexis, but the principle is the
same,” Dr. Olson said. “The only difference is the size. The best
ones are 2 to 3 millimeters. Obviously, it can’t be smaller than the
size of the tear.”
Try to keep the posterior capsulorhexis as
small as possible because it will usually end up larger than
intended, Dr. Singer added. He finds the Inamura Capsulorhexis
Forceps useful for this maneuver because of its downward curve and
crossed-action.
In many cases, a posterior capsulorhexis
makes it possible to implant the IOLs in the bag, especially
single-piece acrylic lenses, which are more easily manipulated
between the anterior capsule and remaining posterior capsule,
explained Richard J. Mackool, MD.
Retrieving the
nucleus. If the vitreous has not prolapsed through the
posterior capsule defect, fill the retrocapsular space behind the
defect. “Many times it may take an entire vial of viscoelastic to
fill the retrocapsular space between the anterior hyaloid face and
posterior capsule remnant. The dispersive viscoelastic serves as an
effective barrier to vitreous prolapse while preventing posterior
dislocation of lens material,” Dr. Singer said. He then
viscodissects or manually moves the remaining lens material up
out of the remaining capsule and into the anterior chamber, where it
can be safely emulsified and aspirated.
Dr.
Wallace pointed out that it is sometimes helpful to insert a
Phacoglide, which is a modified Sheets glide, underneath the nuclear
material so that you can do phaco without coming into contact with
vitreous strands.
If you have a very large rupture and think
you may lose the nucleus, consider extending the phaco incision and
getting the nucleus out before you do a vitrectomy, Dr. Olson
suggested.
Posterior assisted levitation. In
cases where the nucleus is partially descended, Dr. Chang advises
against chasing it with the phaco tip. Instead, he recommends using
a Viscoat posterior assisted levitation method.1 He uses a pars
plana sclerotomy to inject supplemental supporting viscoelastic
behind the nucleus, and then uses the cannula tip to elevate the
nuclear fragments forward through the pupil, under direct
microscopic visualization. “Once the nucleus is in the anterior
chamber, you can manually extract it through a larger limbal
incision,” he said.
Proceed cautiously at a low flow rate,
keeping well away from the rupture, said Dr. Olson. “When doing
irrigation and aspiration, I start out as far as I can in the
peripheral capsule, and I pull out the cortex,” he said. Anytime he
thinks that he is losing the dispersive viscoelastic tamponade, he
injects more viscoelastic.
Only surgeons who have significant
experience should attempt to retrieve nuclear segments that have
been displaced into the vitreous cavity, according to Dr. Mackool.
An alternative is to do a thorough anterior vitrectomy, implant the
appropriate IOL, and then refer the patient to a vitreoretinal
surgeon for completion of lens fragment removal, he
said.
Pars plana vitrectomy. If you have
grabbed vitreous, quit aspirating. Don’t move your tip. “Go back
with your viscoelastic, and start irrigating near the break. Try to
physically sweep the vitreous out of your tip, while pushing it
down, so that you are not stretching it any further,” Dr. Olson
said. To remove prolapsed vitreous, he noted, a pars plana
vitrectomy is the best option.
Dr. Chang agreed: “The pars
plana approach provides a better angle for positioning instrument
tips behind the nucleus.” He uses a disposable #19
microvitreoretinal blade to make the pars plana sclerotomy 3.5 mm
behind the limbus, in one of the oblique quadrants.
With the
pars plana approach, you are pulling the vitreous back, rather than
forward toward your main incision. “All of your net forces are
pushing posteriorly, so you are much less likely to pull a vitreous
strand up to one of your incisions,” Dr. Olson
said.
According to Dr. Olson, leaders in the field have given
up doing a coaxial vitrectomy through the main incision. “You will
always cut out more, and if you are stretching vitreous strands all
the way to your main incision, the chance of retinal detachment or
cystoid macular edema increases dramatically,” he said. Before
starting the pars plana anterior vitrectomy, make sure any remaining
nucleus is completely stabilized and supported.
“If you have
small fragments, or intend to resume phaco, it is important to avoid
aspirating prolapsed vitreous. To avoid posterior descent of lens
material as you excise the supporting anterior vitreous with a
vitrectomy cutter, I use a strategy I call the ‘Viscoat Trap,’”2,3
Dr. Chang said. “After elevating the residual lens fragments toward
the cornea, I fill the anterior chamber with a dispersive
viscoelastic, thereby trapping residual nuclear and epinuclear
fragments.”
He introduces the vitrectomy cutter through the
pars plana sclerotomy with a separated infusion through a
self-retaining limbal cannula. “In this way, I can keep the
vitrectomy tip located in the posterior chamber as I sever any
forward-extending transpupillary bands of vitreous,” Dr. Chang said.
“This prevents evacuation of the partitioning Viscoat layer, which
is now supporting the mobile lens material in the absence of the
vitreous.”
Always have a small irrigating hand piece
available, Dr. Olson suggested. “They are inexpensive, and they come
in 21- and 23-gauge sizes. If you are making a 20-gauge incision,
you need a 21-gauge irrigator. For most of the really small stab
incisions, a 23-gauge is a better irrigator.” Dr. Olson goes through
his stab incision and, using a very low flow rate, he irrigates on
the top from front to back, but not into the opening of the rupture.
“You do not want to irrigate the vitreous,” he said.
This is
one reason that he uses the side-port for irrigation. “If you
irrigate through the main incision, you end up hydrating the
vitreous, blowing fluid right where you are cutting. You have to do
a much bigger vitrectomy, generally, and it is hard to avoid having
vitreous strands coming back up to the wound,” he said. It is a good
idea to stromally hydrate the abandoned main incision, he
added.
Cut the prolapsed vitreous. Use a
vitrectomy tip cutting rate of at least 800 cuts per minute, Dr.
Mackool advised. “A vacuum pressure of approximately 100 to 150 mmHg
and aspiration flow rate of 15 to 25 cc/minute are appropriate for
efficient removal of vitreous. The cutter port would normally be set
to the maximally open position. In most cases, the infusion bottle
must be elevated to at least 90 to 100 centimeters,” he
said.
Dr. Wallace adjusts the vitrector fluidics and cutting
speeds according to the type of expulsate being removed.
Dr.
Mackool noted that it is important to remove all prolapsed vitreous
from the anterior segment, and well behind the plane of the
posterior capsule.
Cut the vitreous from up
above. “Keep cutting as you come back out of the eye,” Dr.
Olson said. “As you get right to the pars plana opening, do just a
little cutting to clean out any vitreous that may be there.”
Finally, put a single stitch to close the pars plana sclerotomy. Dr.
Olson uses a 10-0 nylon stitch. Dr. Chang uses an 8-0 Vicryl suture.
Cover the stitch with the conjunctival flap.
Inserting the
IOL
If you can do a small posterior
capsulorhexis, put the IOL in the capsular bag. If it is a larger
tear, put the lens in the ciliary sulcus and do an optic capture,
Dr. Olson advised. Start with a stable situation with plenty of
dispersive viscoelastic maintaining the anterior
chamber.
Carefully insert the IOL into the sulcus. To make
sure that the IOL goes under the iris and into the sulcus, use a
two-handed technique. “I use one hand to rotate the optic, the other
to compress the haptic. Once I have it in position, I use a Sinskey
hook to push the optic inside the anterior capsulorhexis, and then
slide across and push the other side under,” Dr. Olson
explained.
The anterior capsulorhexis must be between 4.5 and
5.5 mm, a little smaller than the optic, he said. If the anterior
capsulorhexis is too big, the IOL will not stay in place; if it is
too small, it is hard to fit and position the IOL. If the
capsulorhexis is not well-centered, the optic will not be
centered.
If the diameter of the capsulorhexis is
approximately 4.5 mm or smaller, you can capture a multipiece IOL
with an optic of 6 mm or larger, Dr. Mackool added. If the
capsulorhexis is slightly larger (i.e., up to 5.5 mm), you can use
an IOL such as the MA50 Alcon acrylic multipiece lens with a 6.5 mm
optic, he said.
Rhexis fixation of the IOL helps prevent late
IOL decentration and pupillary block by holding the optic centered
and back from the iris, Dr. Singer explained. Reverse optic capture
of a bag-fixated IOL through the anterior capsulorhexis can help to
stabilize the IOL if a noncontinuous or large posterior capsule
defect occurs after implanting the lens, Dr. Singer
added.
Adjust the IOL power. “There are more
complex formulas out there, but this is a general rule that has
worked well for me: If the posterior chamber lens is fully in the
ciliary sulcus, I drop the power by 1 diopter,” Dr. Olson explained.
“When it is captured in the anterior capsulorhexis, I lower the
power by a half diopter. Even with optic capture, however, if IOL
power is more than 23 or 24 diopters, I lower the power one full
diopter.”
Closing the
Case
Remove the viscoelastic. Dispersive
viscoelastic is moderately forgiving, Dr. Olson noted, and he does
not worry about viscoelastic that is sitting behind the capsule. “I
remove the viscoelastic starting in the front and moving back to the
lens. I push the lens back slightly to make sure I have a tamponade,
and take out what is there. I don’t get aggressive about it. I stay
right near the center of the lens, aspirate, push a little bit, and
I can get most of the viscoelastic out,” he
said.
Check for residual vitreous strands.
An intraocular miotic agent helps here. Even the best surgeons may
have a small single vitreous strand coming up to the limbal
side-port incision, Dr. Olson said. “If you see it during surgery,
go ahead and cut that out. If you don’t see it until the end of the
case, and you have already closed your posterior incision, try to
sweep it free. If you see it the next day, and the patient is doing
well; the vitreous is just up to the stab incision and not coming
out through the wound; then watch them carefully. I give it a little
time, and then I use the YAG laser to cut it free,” he
said.
To control inflammation, Dr. Olson prescribes
nonsteroidal anti-inflammatory medications four times a day after
surgery. He also sutures the clear corneal incision in each one of
these cases and removes the suture in a week. “In a study now in
press, we found that a broken capsule or zonules is associated with
a fifteen- to seventeenfold increased risk of endophthalmitis with
clear corneal incisions,” Dr. Olson explained.
But the
techniques and precautions outlined above “can make these cases
routine,” he said.
______________________________________
1 Chang, D. F. and R.
B. Packard. J Cataract Refract Surg 2003;29:
1860–1865.
2 Chang, D. F. Tech Ophthalmol
2003;1(4):201–206.
3 Chang, D. F.
“Strategies for Managing Posterior Capsular Rupture in Phaco Chop,”
in Mastering Techniques, Optimizing Technology, and Avoiding
Complications (Thorofare, N.J.: Slack Inc., 2004).
Staining the
Vitreous |
Filtered Kenalog “staining” of the vitreous¹ is a useful
technique, Dr. Chang said, but he relies on it mainly to
visualize vitreous when an IOL is already present in the
eye.
“These are the situations where prolapsing
knuckles of vitreous get caught, and yet where it is hard to
do a liberal vitrectomy. Therefore, the surgeon may not
realize how much vitreous has prolapsed or is entrapped until
the postoperative slit-lamp examination is performed,” he
said.
Dr. Olson advised caution because Kenalog is
potentially inflammagenic and can cause steroid glaucoma.
“There is a nonsteroidal analog to Kenalog, but it is not
FDA-approved yet,” he
noted.
________________________________ 1 Burk, S.
E. et al. J Cataract Refract Surg
2003;29:645–651. |
Be
Prepared |
While a surgeon’s best efforts can keep the rupture rate
very low, Dr. Wallace said, “we all encounter an occasional
posterior capsular rupture.”
So what do you do? Expect
a rupture at all times. “A small rupture becomes a large one
in a matter of seconds,” Dr. Olson explained. “If you have a
high level of suspicion, you should be able to catch a small
rupture without grasping vitreous about 95 percent of the
time.”
Recognize these danger
signals:
- a failed capsulorhexis
- any unusual tilt of the nucleus during phaco
- sudden deepening of the anterior chamber
- loss of nuclear followability
- visualization of capsular puncture at the end of
phacoemulsification
- any unusual capsular striae at the I&A tip during
cortical removal
- an occult capsular tear that went unnoticed until
cortical removal
Vitrectomy kit It’s also important to
have a vitrectomy kit on hand. Dr. Wallace recommends the
Nichamin System, which includes the following:
- Dispersive viscoelastic
- Phacoglide (Visitec)
- 15-degree or microvitreoretinal blade
- Vitrectomy hand piece
- Separate irrigation hand piece: Storz E4421 or Duckworth
& Kent 8-652-1
|
MEET THE EXPERTS |
Jack A. Singer, MD President,
Singer Eye Center, Randolph, Vt. Financial interests:
None.
R. Bruce Wallace III, MD,
FACS Clinical professor of ophthalmology at
Louisiana State University, New Orleans, and assistant
clinical professor of ophthalmology at Tulane University.
Financial interests: Is a paid consultant for AMO but has
no direct financial interest in any of the products
mentioned.
David F. Chang,
MD Clinical professor at the University of
California, San Francisco, and in private practice in Los
Altos, Calif. Financial interests: Consultant for AMO,
consultant and U.S. medical monitor for Visiogen, and has
received educational travel support from Alcon; no financial
interest in any instruments or devices
mentioned.
Randall J. Olson,
MD Professor and chairman of ophthalmology and
visual sciences, and director, John A. Moran Eye Center,
University of Utah, Salt Lake City. Financial interests:
Consultant for AMO and head of the medical advisory board for
Calhoun Vision.
Richard J. Mackool,
MD Director of The Mackool Eye Institute, and
senior attending surgeon, New York Eye & Ear Infirmary.
Financial interests: Consultant to
Alcon. |