Download Glaucoma and Cataract surgery

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Feature
ESCRS Symposium Report
Lisbon 2005
Glaucoma and Cataract surgery
Roibeard O’hEineachain
in Lisbon
A SYMPOSIUM at the XXIII Congress of
the ESCRS addressed the special challenges
ophthalmic surgeons face when dealing with
co-existing glaucoma and cataract.
Session co-chair Stephen A Obstbaum
MD commented that ophthalmic surgeons
would be encountering more cases of coexisting cataract and glaucoma because of
the aging of the population and because of
newer diagnostic methods which detect
glaucoma at an earlier stage.
However, the approaches to the
treatment of such co-morbidities are
continually evolving and there are currently
many unresolved questions as to the
optimal surgical procedure, he said.
“The approach to the surgical
management of these conditions has been
controversial and dependent on surgical
techniques in vogue at a particular time.
The current emphasis on
phacoemulsification and foldable IOL
implantation and refined methods for
filtration surgery has expanded the surgical
options to manage these conditions.The
introduction of medications that more
effectively reduce IOP has added another
dimension to the decision-making process.”
Current treatment options
Prof Carlo Traverso MD followed with an
overview of the current surgical approaches
in the treatment of patients with cataract
and glaucoma.
The European Glaucoma Society (EGS)
has designed a flowchart of recommended
treatments for primary open-angle
glaucoma patients with co-existing cataract.
The guidelines provide recommendations
based on how well IOP is controlled and
the extent of damage to the visual field.
The recommendations are very
straightforward concerning the appropriate
treatment for those with very mild or very
severe disease, but are somewhat equivocal
concerning patients in the more moderate
categories.
For example, the sole recommendation
for treating patients with high IOP who are
on multiple medications and have severe
visual loss is to perform glaucoma surgery
first and phacoemulsification later. In those
with normal IOP on monotherapy and only
early or moderate visual loss, the guidelines
recommend phacoemulsification first
followed by glaucoma surgery.
Combined approaches gaining favour
Prof Traverso noted that historically the
management of cataract and glaucoma
involved sequential surgery, usually
glaucoma surgery followed by cataract
extraction once the intraocular pressure
was controlled and the bleb evolved.
“The success rate of combined
extracapsular cataract extraction and
glaucoma filtration surgery was not ideal,
supporting a rationale for a sequential
approach. However, in the last decade, the
success of small incision
“In the last decade, the success of small incision
phacoemulsification and filtration surgery with antimetabolites, has caused a widespread switch from sequential
to combined surgery by most glaucoma surgeons”
Prof Carlo Traverso MD
“In the presence of both cataract and
glaucoma you need to think exclusively of
the best option for your individual patient,”
he said.
He noted that among the decisions that a
surgeon must make in such cases are
whether to use a sequential or combined
approach, whether to perform the surgery
on one or two sites, and whether to use
trabeculectomy or non-penetrating
glaucoma surgery.
In the case of chronic angle-closure
glaucoma a surgeon has also to consider
whether IOP can be brought under control
by iridotomy or cataract surgery alone. In
such cases the cataract itself may play a
role in the aetiology of the glaucoma, Prof
Traverso said.
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phacoemulsification and filtration surgery
with anti-metabolites, has caused a
widespread switch from sequential to
combined surgery by most glaucoma
surgeons.”
Drainage implants
Drainage implants are another adjunct to
combined procedures that have shown
promising results in clinical trials, he noted.
One of these is the Glaukos™ Trabecular
Bypass Micro Stent.The stent is placed
within Schlemm’s canal using an ab-interno
procedure. By creating a trabecular bypass,
the implant allows the aqueous humour to
enter Schlemm’s canal via both the bypass
and the trabecular meshwork. It drains out
of the canal via collector channels to
aqueous and episcleral veins. No bleb is
formed.
In a study involving 47 patients who
underwent phacoemulsification and
implantation of the Glaukos microstent,
87% achieved their target IOP six months
postoperatively, he said.
One-site phacotrabeculectomy
One-site phacotrabeculectomy techniques
generally commence similarly to a standard
trabeculectomy but become more
complicated during the phacoemulsification
phase of the procedure.
When performing such procedures the
“When doing combined cataract and glaucoma surgery a
patient will be exposed to just one surgical session and
there is less risk of IOP spikes just after surgery”
Roberto Carassa MD
“Implantation of the iStent™ seemed to
be safe and effective in reducing the IOP
without conjunctival incision or
complications traditionally associated with
limbal filtering procedures. While these
initial results are promising, longer-term
follow-up and additional clinical studies are
warranted,” Prof Traverso said.
Another drainage implant is the ExPRESSTM. This device is positioned at the
limbus and acts as a shunt for the aqueous
from the AC to the subconjunctival space.
Initially this procedure was performed
under a conjunctival flap; in case of less
than perfect placement of the implant
however, the risk of erosion was observed.
After favourable reports from studies by
Dahan and Carmichael, an implantation
technique under a scleral flap is rapidly
becoming popular as it prevents the risk of
erosion.
One-site v two-site surgery
Roberto Carassa MD told the symposium
that combined approaches are indicated in
cases of advanced glaucoma with coexisting cataract. He also maintained that a
two-site approach provides the surgeon
with greater flexibility and safety and
allows the use of their preferred
techniques in both the cataract and
glaucoma phase of the procedure.
“When doing combined cataract and
glaucoma surgery a patient will be
exposed to just one surgical session and
there is less risk of IOP spikes just after
surgery. This has implications when we are
dealing with advanced glaucoma. With a
two-site approach things are certainly
easier because we are performing surgery
we are used to.”
In one-site techniques,
phacoemulsification is performed through
the filtration surgery incision. Two-site
techniques generally involve first
performing phacoemulsification in the
temporal quadrant and then carrying out
standard glaucoma surgery in the upper
quadrant, Dr Carassa explained.
surgeon first creates a fornix-based
conjunctival flap in the superior quadrant,
and then makes a groove 3.0-4.0mm deep,
2.0mm posterior to the limbus, followed by
dissection of a scleral flap with a crescent
knife 1.0mm anteriorly in clear corneal
tissue.
Following creation of a paracentesis,
viscoelastic is injected into the anterior
chamber and phacoemulsification is
performed through the tunnel opening. An
injection of acetylcholine is used to dilate
the pupil.
After cataract extraction and IOL
implantation, the surgeon transforms the
tunnel into an “L” or “U” shape with two
lateral cuts at the edge of the flap, thereby
exposing the internal end of the flap and
allowing greater outflow of aqueous.The
surgeon performs trabeculectomy using a
blade trephine or punch and performs an
iridectomy to prevent the iris from plugging
the filtration.The procedure concludes with
the closure of the scleral and conjunctival
flap and aspiration of the viscoelastic.
“One-site phacotrabeculectomy is a
completely different procedure when
compared with standard
phacoemulsification or standard
trabeculectomy,” Dr Carassa said.
One-site combined procedures using
non-penetrating surgery involve an
additional level of complexity, he noted.
In such procedures, the surgeon will
generally proceed as with a normal nonpenetrating technique until Schlemm’s canal
is exposed, just before cleaving the sclerodescemetic membrane. At this point the
surgeon will make a tunnel between the
internal and external flap and perform
regular phacoemulsification and then cleave
the sclero-descemetic membrane and
complete the glaucoma surgery as usual.
Evidence supports higher efficacy of
two-site technique
Dr Carassa said that perhaps the only
advantage of one-site techniques is that
they are faster. He cited two studies that
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Stephen A Obstbaum
Roberto Carassa
Philippe Sourdille
indicated that the two-site technique is
more effective in reducing IOP than the
one-site technique.
In one of the studies (Wyse T et al.: AJO,
1998), patients who underwent the two-site
technique had a mean of IOP 13.3 mmHg
and required a mean of only 0.2 glaucoma
medications. By comparison, patients who
underwent one-site surgery had a mean
IOP of 15.3 mmHg and required a mean of
0.8 glaucoma medications.
In the second study (El Sayyad F et al.:
JCRS, 1999), which involved 76 eyes,
patients in the one-site group had a mean
IOP of 19.1 mmHg after the one-site
technique, compared to 17.6 mmHg in the
two-site group.
Two-site techniques also have numerous
safety advantages over one-site techniques,
he noted.They involve less manipulation of
the conjunctiva and sclera, there is less risk
of anti-metabolites entering the anterior
chamber, and postoperative suture removal
or adjustment will not affect the scleral
incision.
“The major points affecting the overall
outcome of our combined glaucoma and
cataract surgery are the use of mitomycinC, two-site technique, and the use of
phacoemulsification instead of ECCE. By
following all these recommendations we
can get the best results with our combined
procedures.”
The case for sequential surgery
Philippe Sourdille MD suggested that
combined procedures should be used
selectively in order to avoid the use of antimetabolites.
“More and more phacotrabeculectomies
are routinely performed with application of
mitomycin-C and this makes them prone to
complications such as hypotony,
maculopathy, bleb leak, blebitis and even
endophthalmitis with a final loss of visual
acuity,” he said.
Indications for a sequential approach
include glaucomatous eyes with incipient
cataracts and those with closed-angle
glaucoma.
In eyes with incipient cataracts, where
visual impairment is mild and cataract
surgery is not urgent, he recommended the
use of non-penetrating glaucoma surgery
techniques because they are less
cataractogenic than standard
trabeculectomy.
“In the AGIS study, at five years an
incidence of 87% of cataract was noted
after trabeculectomy. In contrast, all the
published literature indicates a rate less
than 10% after non-penetrating surgery.”
In eyes with primary closed-angle
glaucoma and cataract he recommended
first removing the cataract and assessing
the effect of the procedure on the IOP.
I Howard Fine
Alan Crandall
Influence of cataract surgery on IOP
When performing cataract surgery in eyes
that have undergone previous filtration,
surgeons should consider the effect the
procedure will have on the eye’s IOP, he
said. Several studies have shown that
cataract procedures increase IOP slightly in
about half of eyes for a year or more.
“More and more
phacotrabeculectomies are
routinely performed with
application of mitomycin-C
and this makes them
prone to complications
such as hypotony,
maculopathy, bleb leak,
blebitis and even
endophthalmitis with a
final loss of visual acuity”
Philippe Sourdille MD
“You may consider that 2.0mm in IOP
elevation would not be significant, but
should the IOP already be above the target
pressure at the time of cataract surgery
this 2.0 mmHg rise can be deleterious to
the visual field.”
Dr Sourdille recommended carefully
watching the influence of infusion on the
bleb height during surgery. In this way it is
possible to assess whether to consider
additional steps such as bleb revision, antimetabolite injection, scleral flap revision or
reopening or re-operation at a later time.
“IOP elevation will be dangerous for the
optic nerve and hypotony can be
deleterious to the filtration so we should
be very careful to ensure the postoperative
tightness of the wound and remove all of
the viscoelastic and monitor postoperative
IOP and inflammation.”
Dr Sourdille noted that most of the
published literature suggests better IOP
control can be achieved with
trabeculectomy than with
phacotrabeculectomy, whether or not antimetabolites are used. However, he noted
that some investigators have reported
results equivalent to those of
trabeculectomy alone in combined
procedures involving deep sclerectomy.
“Routine phacotrabeculectomy does not
apply to all cases of coexisting cataract and
glaucoma. Sequential procedures should be
considered in glaucomatous eyes with
Robert Stegmann
incipient cataract and in such cases noncataractogenic glaucoma surgery should be
the procedure of choice” he added.
Management of the miotic pupil
Turning to some of the specific challenges
faced by surgeons dealing with cataracts in
glaucoma patients, I Howard Fine MD
addressed the issue of miotic pupils.
“One of the problems with cataract
surgery in glaucoma patients is the frequent
incidence of small pupil, which can often be
intractable.”
He described his own approach in such
eyes, which he said involves proceeding
from the least invasive to the more invasive
approaches until the pupil can be dilated
sufficiently for phacoemulsification.
In such eyes, he commences his
procedures as he would in an eye with a
normal pupil. Under the upper eyelid he
places a surgical sponge dripped in a
solution containing a local anaesthetic
(Marcaine-MPF 0.75%, 12.5cc), mydriatics
(Mydriacyl 1.0%, 2.5cc) (Cyclogel 2.0%
2.5cc), anti-inflammatories (Flurbiprophen
0.03%, 2.5cc) and antibiotics (Vigamox
0.5cc, Alcon).The sponge is left under the
eyelid, which he tapes closed for 15
minutes. If the pupil does not seem to
dilate adequately he adds additional
mydriatic drops.
In patients prone to floppy iris syndrome
because they are receiving the agent
tamusolin (Flomax, Boerhinger Ingelheim),
patients are prescribed atropine 1% one
week before surgery.
“In these cases I believe that bimanual
microincision phaco is an added advantage
because although the iris will still come to
the incision it doesn’t extrude and because
of the ability to separate infusion from the
phaco tip we can have the fluid circulating
above the iris. “
Lester hooks
If the pupil still remains inadequately
dilated, Dr Fine then begins a series of
additional steps, starting with the use of
two Lester hooks. Injection of viscoelastic
can also aid in pupil dilation.
“It is important to stretch the pupil
slowly because it is easy to damage the iris.
It’s important also to stay in a horizontal
plane so as not to damage the zonules. I try
to avoid going into the incision location
with stretching because we tend to get
ruptures in the sphincter, which tend to be
a little bit floppy.We also get less chance of
extrusion if we stretch it in meridians that
are not in the meridian of the incision or
the sideport.”
If this manoeuvre is insufficient Dr Fine
said that he will then proceed to use a
Beehler pupil dilator.The device comes in
two forms, one with three prongs, which
fits through 2.5mm and another with three
prongs, which requires a 3.0mm incision.
Both have a hook at the base of the
cannula, which allow the surgeon to reflect
the subincisional portion of the pupil.
“The prongs will essentially stretch the
pupil closer to the dimension of the
circumference of the base of the iris rather
than just the diameter of the pupil. Slow
stretching is very important and the use of
viscoelastics following the stretching of the
pupil adds to the increased size of the pupil
and very often it allows you to perform
surgery in the usual manner in an
inhospitable pupil.”
Hydro-express the cataract
An additional technique is to hydro-express
the cataract into the plane of the pupil so it
is vertical rather than horizontal.The bulk
of the cataract will hold the pupil open
throughout the case. Using bevel down
phacoemulsification at this point prevents
fluid from going under the iris.
“In situations like this, you don’t
disassemble the nucleus by chopping or
cracking.We just try to phaco it from inside
out with a gradual diminution of the size of
the cataract bulk. Another benefit is that all
the energy goes toward the cataract and
none toward the corneal endothelium or
toward the trabecular meshwork.”
If the pupil should constrict after removal
of the nucleus there can be some difficulty
in visualising the cortex. Injection of Healon
5 (AMO) will usually re-dilate the pupil
adequately.The cortex can then be stripped
circumferentially following the margin of
the capsulorhexis. However, it is important
to disallow clearance of occlusion to avoid
aspiration of the viscoelastic, he said.
Stripping the pupillary membrane is
another technique that some surgeons find
useful, he said. A fibrotic membrane is often
the cause of the pupil’s miosis. Another
technique is to make mini-sphincterotomies
with Rappazzo scissors, making incisions
that are halfway through the thickness of
the sphincter but are full thickness in the
anterior and posterior dimension.
“After making these minisphincterotomies we stretch these areas
where we cut.This leaves a peripheral rim
of muscular tissue in the pupillary sphincter,
which allows for normal function
postoperatively. I always reduce the pupil
mechanically to reduce adhesions between
pupil and capsule physiologically functional
and cosmetically acceptable.”
Dr Fine said that, as a final resort, he will
use a pupillary expander ring implanted
with either two forceps or with an injector.
By providing a broad area of contact against
the iris, the rings can safely and efficiently
dilate very weak and most miotic pupils
without damaging the iris.
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Special Focus
Enhanced viscocanalostomy
Robert Stegmann MD concluded the
symposium with a description of his new
enhanced viscocanalostomy technique
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While glaucomas represent a very
heterogeneous group of conditions, one
factor they all have in common is that they
involve a collapsed, dysfunctional
Schlemm’s canal, Dr Stegmann noted.
Trabeculectomy, along with most of the
non-penetrating techniques, are
fistularising procedures, which direct the
aqueous fluid to the conjunctiva where a
filtering bleb is formed. In contrast,
viscocanalostomy provides a channel for
aqueous through the Descemet’s window
into a scleral lake, from which the fluid
drains out through Schlemm’s canal as it
does in the normal healthy eye.
Up to now the problem with
viscocanalostomy has been that it has not
been possible to open Schlemm’s canal
throughout its complete circumference.
However, a new microcatheter has made it
possible to not only expand the canal
completely but also to draw a suture
through the canal to insure its long-term
patency.
The new microcatheter is produced by
iScience and has a diameter of 200
microns and an atraumatic soft tip. A
helium-neon light source shone through an
optical fibre illuminates the catheter tip,
which also contains a polyamide lumen for
the injection of sodium hyaluronate.
In addition, a new high-resolution
ultrasound system, also produced by
iScience provides accurate localisation of
Schlemm’s canal and can also provide
confirmation of the success of the
procedure.
Microcatheter technique
When using the microcatheter, Dr
Stegmann commences as he would with a
conventional viscocanalostomy procedure.
He first dissects a parabolic flap in the
sclera to a depth of 250 to 300 microns
and then dissects a further 300 or 400
microns down to a level that is just
superficial to the choroid to create a
scleral lake. He then dissects forward to
reveal the canal of Schlemm and creates a
Descemet’s window.
He then gently insufflates the surgically
created ostia with a viscoelastic, which
serves as a lubricant to allow the safe
insertion of the microcatheter. As he
passes the microcatheter through the
canal of Schlemm he uses a micrometer
syringe to deliver 0.02ml of viscoelastic
per 1/8 turn on the micrometer screw.
Once he has passed the microcatheter
360 degrees through Schlemm’s canal and
it emerges at the operative site he
attaches two 10-0 prolene sutures to the
catheter, which he then draws back
through the canal. After withdrawing the
catheter, he ties off the ends of the
sutures with a special slipknot to create
20 grams of tension.
“This opens the canal internally so that
the ostia you have created will not close
postoperatively,” he said.
He noted that the high success rate in
his African glaucoma patients, among whom
the mean pre-operative IOP is 47-49
mmHg, suggests it should be even more
effective in Caucasian glaucoma patients,
among whom the mean IOP is 24-25
mmHg. Dr Stegmann said that he has had a
success rate of about 79% in his African
population, while his associates in America
are reporting success rates of around 92%.
“What is most encouraging is that with a
maximum follow-up of 11 months, 92% of
cases have reached episceral venous
pressure.”
[email protected]
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[email protected]
[email protected]
[email protected]
Catheter just prior to insertion. Note the illumination of the catheter tip from the
helium-neon light source
The catheter tip at 9 o'clock. The illuminated tip informs the surgeon of the catheter’s location
throughout the procedure
The catheter tip at 6 o'clock. The illuminated tip informs the surgeon of the catheter’s location
throughout the procedure
The catheter being withdrawn after passing through the complete circumference of Schlemm’s canal
Courtesy of Clive Peckar FRCS FRCOphth
Capsular tension rings
Alan Crandall MD followed with a
presentation on the use of capsular tension
rings in eyes with weak zonules, a condition
that can occur in eyes of patients with
conditions that make them prone to
glaucoma and can also occur as a result of
glaucoma surgery.
“Capsular tension rings are used in about
five per cent of cataract procedures and
convert a high risk case into a routine case.
They are designed to maintain the capsule’s
contour and stretch the posterior capsule
when there is zonular dehiscence or
rupture occurs after blunt or penetrating
injury, or surgical trauma, or when there is
inherent zonular weakness.”
Capsular tension rings can be used for
intraoperative support and then removed
later, or can be sutured in. In addition to
facilitating IOL implantation, they promote
IOL centration and can be used for resuturing a late dislocated in-the-bag
intraocular lens.
Among the indications for capsular
tension rings are systemic conditions such
as Marfan’s syndrome and WeillMarchesanie syndrome, ocular conditions
such as pseudoexfoliation and high myopia,
and eyes that have undergone previous
glaucoma filtration surgery and previous
RK.
There are various models of capsular
tension ring available.There are the
standard capsular tension rings by Morcher
and Ophtec, which include variations for
highly myopic eyes.There are also the
Sundmacher and Rasch Rosenthal Morcher
models, which incorporate artificial irises
for aniridia or iris trauma.
Of particular value in the treatment of
cataracts in glaucoma patients is the Cionni
Capsular Tension Ring (Morcher), which has
a special eyelet that sits above the capsule
for scleral fixation.There are also new
capsular tension ring segments that are
smaller and are easier to use
intraoperatively, and which can also be
sutured to the sclera, Dr Crandall said.
Capsular tension rings may be inserted at
any stage of a phacoemulsification
procedure, either with a Geuder injector or
manually with forceps. Grieshaber iris
hooks may be needed to suspend the bag
prior to insertion of the ring.
Hydrodissection facilitates the procedure
and “slow motion” phaco is necessary, he
noted.
Inserting the rings prior to phaco affords
greater nuclear stability although it is
difficult in cases with dense lenses where
there is a risk of iatrogenic zonular damage.
The presence of the ring can also make
cortical removal more challenging. Inserting
the rings after phacoemulsification is
generally easier. Iris hooks should be used
during phaco and cortical removal, Dr
Crandall advised, adding:
“Early placement of a CTR does result in
some bag torque and zonular stress
therefore we suggest using it as late as you
can during the procedure.”