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Techniques in Ophthalmology 6(3):98–104, 2008
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I N S T R U M E N T A T I O N
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Techniques of Endoscopic Cyclophotocoagulation
Jon Weston, MDFACS
Weston Eye Center
Roseberg, OR
| ABSTRACT
Endoscopic cyclophotocoagulation is an exciting and
novel approach to the management of glaucoma. The
basic principal is quite simple. Aqueous production
(inflow) is diminished by photocoagulating the epithelium of the ciliary processes. The technology, the various
technical iterations, the results, and the complications
will be discussed.
| HISTORICAL PERSPECTIVE
Inflow reducing surgical procedures have had a sordid
history mostly characterized by poor outcomes and substantial complications. Difficulties were mainly due to
the lack of direct visualization of the target tissue and
by poor control of the destructive force. Collateral damage to healthy tissue from external cyclodestruction leads
to significant inflammation and complications. The
transvitreal approach to cyclophotocoagulation was first
described by Charles,1 wherein the eye first underwent
vitrectomy and lensectomy. The ciliary processes were
then scleral depressed into the view of the operating
microscope and photocoagulated under direct visualization. The first study of this approach was by Patel and
Thompson2 in a cohort of intractable glaucoma patients
treated by this transvitreal method. A high degree of
intraocular pressure (IOP) control was obtained with
few complications. Unfortunately, this approach to glaucoma treatment is beyond the scope of most ophthalmologists and involves extensive intraocular surgery. Uram3
devised the notion of combining endophotocoagulation
with endoscopic imaging and demonstrated the ability
to access the ciliary processes and photocoagulate them
from both a limbal or a pars plana approach and circumventing their lens status, whether phakic, pseudophakic,
or aphakic. He described the application of endoscopic
cyclophotocoagulation (ECP) across an array of glaucoma mechanisms and levels of severity. Since that
time, numerous reports have corroborated the initial findings so that today ECP is the most commonly performed
inflow reducing procedure in the United States.4
Address correspondence and reprint requests to Jon Weston, MD,
FACS, Weston Eye Center, 2435 Kline Street, Roseberg, OR (e-mail:
[email protected]).
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| TECHNOLOGY
To benefit from this approach to glaucoma surgery, the
practitioner must have an understanding of the basic technology involved. There are 2 sets of components, the first
are the laser endoscopes themselves, and the second is the
laser and endoscopy console.
Currently, the laser endoscope is a 20-gauge instrument that incorporates a 10,000-pixel image guide with
a wide view, a plurality of light fibers, and a single laser
fiber. The endoscope may be in a straight or a curved configuration (Fig. 1). This instrument permits delivery of
image, illumination, and laser to the target tissue.
The console (Fig. 2) contains a videocamera, light
source, and semiconductor diode laser tuned to the
810-nm wavelength.
| TECHNIQUE
The surgeon must acquire 4 skills that are used during
ECP. The first of these is that the surgeon views the course
of surgery on the video monitor of the endoscopy system
(Fig. 3) rather than looking through the operating microscope. This is a foreign experience to most ophthalmologists and requires some adaptation. The second skill is to
learn how to access the ciliary processes given an anterior
or a pars plana approach and depending on the lens status
of the patient. The third skill is learning how to properly
and adequately inflate the ciliary sulcus. Finally, the surgeon must learn how to use an ‘‘invisible’’ wavelength
laser with long duration applications. All of these will be
discussed.
| VIDEO MONITOR VIEWING
The surgeon must place the video monitor adjacent to the
operating table in a convenient location so that the image
may be viewed from not too great a distance. Typically,
the surgeon places the laser and endoscopy system adjacent
to the operating room stretcher on the opposite side of where
one would place the unit for phaco and/or vitrectomy.
| ACCESSING THE
CILIARY PROCESSES
The surgeon must decide whether a limbal or a pars plana
approach would be most useful. Most ECPs are performed
from a limbal approach; however, a pars plana approach
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Techniques of Endoscopic Cyclophotocoagulation
FIGURE 1. Straight and curved tip microendoscopes.
can be quite helpful when there is marked disruption of the
anterior segment architecture complicating a limbal entry.
| LIMBAL APPROACH
The ciliary processes may be accessed from an anterior
segment incision in the phakic, pseudophakic, or aphakic
eye (Figs. 4A, B, 5A, B, and 6A, B) and may be combined
with cataract surgery as well.
A basic concept is that if there is a lens posterior
to the iris, then one must inflate the sulcus with a sodium
hyaluronate viscoelastic. The maneuver opens the potential space that exists between the iris and the anterior
portion of the lens permitting access to the processes.
One must inject sufficient viscoelastic so as to view
the entirety of each ciliary process and view the zonules
emanating from the more posterior aspect of the processes. This technique works well to create a wide
approach to the processes and protects the posterior
aspect of the iris and anterior portion of the lens from
contact with the endoscope.
| APHAKIA AND ANTERIOR
CHAMBER PSEUDOPHAKIA
In this scenario, there is no lens to displace behind the iris,
and so viscoelastic for this purpose is not required. On the
FIGURE 3. Endoscopic view on monitor.
other hand, many of these eyes comprise a ‘‘single chamber’’; that is, the aqueous flows freely from the anterior to
the posterior segment without a separating barrier, and
often these eyes have had a least a partial vitrectomy as
well. They are prone, therefore, to intraoperative hypotony, which is always undesirable but especially in glaucomatous eyes. It is important therefore to maintain some
measure of perfusion by inserting an anterior chamber
maintainer at the initiation of surgery with free-flowing
balance salt solution into the eye. Once this has been
established, then the endoscope may be inserted through
a limbal incision through the pupillary space and often
will easily and directly view the ciliary processes. Photocoagulation may then be applied.
| COMBINED ECP AND
CATARACT SURGERY
FIGURE 2. Laser and endoscopy system console.
There are several approaches to the ciliary processes
via the cataract surgery incision site. One approach is
to empty the capsular bag of its contents then inject the
viscoelastic ‘‘over the bag.’’ This maneuver collapses
the capsular bag and directs it posteriorly while creating
a bombe’ effect of the iris. The ciliary processes are then
easily seen and photocoagulated. The capsular bag is
then reinflated for lens implantation. A variation of the
over the bag approach is for the surgeon to perform the
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anterior segment surgeries. This approach is useful
in the aphakic or pseudophakic eye (Figs. 7A, B) but
cannot be performed in the phakic patient. In this approach, there is no lens to displace, and so viscoelastic
is not required. It is best to remove at least the anterior vitreous in this situation by performing a vitrectomy. This method is quite simple. Perfusion of the
eye is required either through an anterior chamber
maintainer or pars plana infusion cannula. An incision
is created 4 mm from the limbus. The laser endoscope
is inserted into the eye and tilted anteriorly to view the
processes.
| METHOD OF CILIARY PROCESS
PHOTOCOAGULATION
The goal of the surgery is to completely whiten the
entirety of each process in the treatment zone and to
avoid photocoagulating the posterior aspect of the iris,
intraocular prosthetic devices, and other nonaqueous producing tissue. ‘‘Popping’’ the ciliary process represents a
FIGURE 4. A, Limbal approach, phakic eye. B, View of
ciliary processes from a limbal approach in a phakic eye.
entire phaco-IOL insertion and remove all viscoelastic, as
if the surgery were complete. Then a sodium hyaluronate
viscoelastic may be injected over the capsular bag containing the lens implant and posterior to the iris, once
again opening the potential space that exists in the region
of the sulcus and permitting observation and coagulating of the processes. This is the most commonly used
method. A third approach is ‘‘through the bag.’’ In this
scenario, the capsular bag is emptied of its contents
then viscoelastic is injected into the bag. The laser endoscope is then inserted through the pupil into the capsular
bag and directed toward the ciliary processes. Although
the view is slightly blurred because viewing takes place
through the capsular bag, the access to the ciliary processes and pars plana region is quite good. Photocoagulating through the bag has not been reported to create any
postoperative difficulties.
| PARS PLANA APPROACH
This is a simple method for accessing the ciliary processes especially when the eye has had many previous
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FIGURE 5. A, Limbal approach, pseudophakic eye. B,
View of ciliary processes from limbal approach in a
pseudophakic eye.
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Techniques of Endoscopic Cyclophotocoagulation
typical extensive treatment, but on the other hand, if, for
example, 50% of the ciliary body was nonfunctional and
then 360 degrees were to be treated, hypotony might
evolve.
| HUMAN HISTOPATHOLOGY
Endoscopic cyclophotocoagulation can be differentiated
from other inflow reducing procedures based on its histologic effect. It has been well documented in multiple
studies that ECP is specifically ablative to the epithelium
of the ciliary processes and spares underlying structures,
especially the vasculature. Because it is applied under
direct visualization, other intraocular structures are typically not included in the treatment zone. On the other
hand, all of the transscleral modalities of cyclodestruction incorporate all tissue in the treatment region and
especially the ciliary body vasculature. In addition, anatomic variation induced either by previous surgery or by
development may result in incorporation of the iris or
FIGURE 6. A, Limbal approach, aphakic eye. B, View of
the ciliary processes from a limbal approach in an aphakic
eye.
tissue explosion with rapid gas bubble formation and pigment dispersion. This is undesirable and should be
avoided. Because ECP is performed with a near infrared
laser wavelength, there is no visible laser ‘‘flash’’ when it
is fired. One uses very long duration applications lasting
for many seconds while ‘‘painting’’ the ciliary ring.
Because the progress of photocoagulation can be directly
monitored and well controlled using relatively low power
(200-300 mW) with long duration applications, it is relatively simple to create the desired tissue effect while
avoiding the problems previously mentioned.
Most patients require 270 to 360 degrees of treatment
to have a reliable, consistent, and long lasting effect. Less
treatment results in variable outcomes. The only exception to this is ischemic eyes, typically those with neovascular glaucoma. In that situation, the surgeon cannot
know how much of the ciliary body is nonfunctional
before surgery. If there is essentially normal aqueous production in such an eye, then the patient would require the
FIGURE 7. A, Pars plana approach, pseudophakic eye.
B, View of the ciliary processes from a pars plana
approach in a pseudophakic eye.
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retina in the treatment zone with its associated untoward
effects.
| DISCUSSION
Endoscopic cyclophotocoagulation has been used in the
treatment of an array of glaucoma mechanisms. These
vary from treating ultrarefractory glaucomas that have
failed multiple surgeries to combining it with phaco to
manage medically controlled glaucoma.5Y23
Endoscopic cyclophotocoagulation was first reported by Uram,24 in the treatment of uncontrolled neovascular glaucoma. Other reports include patients with
uncontrolled open-angle, chronic angle closure, postpenetrating keratoplasty, and pediatric mechanisms. In
general, successful control of IOP was performed in
approximately 90% of treated eyes. Complications that
would typically be associated with the transscleral
form of cyclodestruction have been reported rarely. In
their safety study, the ECP collaborative group reported
their findings at the ASCRS 2007. In this study, 5824
eyes were evaluated for complications arising from
ECP and stratified according to mechanism of glaucoma. The mean follow-up in this group was 5.2 years.
The most commonly observed problem was a postoperative IOP spike being seen in 14.5% of eyes. This was
universally caused by retained viscoelastic. Transient
intraocular hemorrhage was observed in 3.8% of eyes.
Serous choroidal effusion was observed in 0.4% of
eyes, and most of these occurred in patients with refractory forms of glaucoma. Intraocular lens displacement
was seen in 0.4%, and all of these were seen in either
refractory forms of glaucoma or neovascular glaucoma.
Cystoid macular edema developed in 0.7%. This finding
is in keeping with most series on intraocular surgery and
is certainly vastly better than what is typically seen with
transscleral forms of destruction where this problem is
observed in the 40% to 50% range. Visual loss greater
than 2 lines was seen in 1.03%. Retinal detachment occurred in 0.2%. Choroidal hemorrhage, hypotony, phthisis,
and progression to no light perception vision were seen in
0.1% of eyes. All of these patients presented with refractory or neovascular forms of glaucoma. Interestingly, no
patients with open-angle or pseudoexfoliative glaucoma,
postpenetrating keratoplasty glaucoma, or medically controlled glaucoma combined with phaco developed these
issues. In addition, no patients in any group developed
chronic inflammation or endophthalmitis. Considering the
extremely large study cohort with extensive follow-up, it is
clear that ECP exhibits a high safety profile and perhaps
may be the safest glaucoma surgical procedure.25Y30 In
the post-PK glaucoma group of 57 eyes, 3 patients experience acute graft rejection with subsequent resolution, and
none of the patients were found to have chronic graft re-
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jection and failure. This is significant considering that
tube implantation in the setting of post-PK glaucoma has
high potential for engendering graft failure.31,32
| COMBINED PHACO-ECP IN THE
SETTING OF MEDICALLY
CONTROLLED GLAUCOMA
There is no historical precedent for combining an inflow reducing procedure with cataract surgery. Indeed,
it would be inconceivable to perform a brutal transscleral cyclodestructive procedure with sophisticated phaco
and intraocular lens implantation. Uram7 reported the
first group of eyes where ECP was combined with
phaco and posterior chamber intraocular lens implantation. This proved to be highly efficacious with no significant complications. The first suggestion to combine
ECP with phaco in the setting of medically controlled
glaucoma was made by Richard Mackool. The goal of
this approach was not to lower IOP per se but rather
to allow a lower IOP with fewer medications. In his
unpublished study of 24 phaco-ECP patients and 22
phaco-alone eyes, 87% of the ECP group decreased
their medications whereas only 9% of the phaco-alone
eyes did. No significant complications were observed
in either group.33
Subsequently, this approach to glaucoma treatment
has become widespread. 4 Berke et al 34 reported the
first cohort of ECP combined with phaco in the treatment
of medically controlled open-angled glaucoma in a retrospective analysis. The group reported their findings in a
randomized, controlled study of phaco combined with
ECP versus phaco alone in the management of medically
controlled glaucoma and cataract with follow-up of 3.2
years. They found that the natural history of glaucoma
after phaco was a gradual decline in IOP over the course
of approximately 18 months only to slowly rise over the
following year to slightly higher than initial levels without experiencing a decrease in number of medications
used. On the other hand, the phaco-ECP cohort experienced a significantly greater decline in IOP as well as
a significant decrease in number of glaucoma medications used that persisted throughout the follow-up
period. The treatment group experienced an average
decrease of $1500 per year in glaucoma medication expenditure after combined treatment whereas the phacoalone group did not. This work represented the largest
glaucoma surgical study of any type, and the control
group by itself represented the largest evaluation of
IOP and glaucoma medications after phaco. These findings are supportive of the notion that confronted with
the cataract surgery patient who also has medically controlled glaucoma, a better long-term outcome may be performed by adding ECP to phaco both in IOP control and
Techniques in Ophthalmology
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Techniques of Endoscopic Cyclophotocoagulation
medication utilization than performing phaco alone and
continuing the patient’s regimen of glaucoma treatment.
This is especially significant considering that adding
ECP to phaco did not increase the risk of complications.
| CONCLUSIONS
Endoscopic cyclophotocoagulation is a versatile and
straightforward technique with a long record of safety
and efficacy. It is one that can be rapidly mastered by
most ophthalmic surgeons. It is unlike other sophisticated glaucoma surgical procedures that are useful
only in uncontrolled forms of glaucoma and with specific anatomic and pathophysiological limitations.
Endoscopic cyclophotocoagulation may be incorporated into the practice of most ophthalmic surgeons
and may be used on a frequent basis for the treatment
of a wide range of glaucoma mechanisms and disease
severity.
TIPS ON GETTING STARTED
Your certification course will prepare you for your
first cases. A few ideas mentioned here may be
helpful.
1. Turn down the room lights and the microscope
light as well. This will make visualization of the
monitor easier and avoid photo toxicity.
2. Your standard incision for lens insertion should be
adequate for the endoprobe. You can lift the superior lip of the incision with any manipulator or start
with the probe at 45 degrees to ease entry.
3. Practice viewing the ciliary sulcus on several cataract cases. Keep illumination low at first to avoid
washing out anatomic details and the aiming
beam. This will get you familiar manipulating the
probe while viewing through the monitor. You may
be surprised at how much residual cortex you see at
the equator.
4. Try to keep 3 ciliary processes in view at all times
as you progress. This will help you maintain a consistent working distance and avoid the need to constantly change laser energy. Too close and you have
to lower energy to avoid getting excessive tissue reaction, too far and you have to raise power
significantly.
5. The tendency at first is to torque the eye while getting at 270+ degrees of treatment. Look back
through the microscope periodically to maintain a
neutral position, pivoting the probe at the incision.
Instruct your scrub to monitor this even when you’ve
become familiar with the procedure.
6. I suggest beginning with the straight probe and 2
incisions until you are very comfortable with the
procedure. This will facilitate getting a complete
treatment.
7. In some surgeon’s hands, 270 degrees can be
visualized and treated through a single incision
with the curved endoprobe. Practice as above by
maintaining a constant viewing distance by rotating
the probe with the finger tips as you progress. This
will require more active adjustment of the orientation of the image by your laser assistant, so it is
all the more important to have someone trained
and experienced working with you.
8. Always clean the probe immediately after removing
it from the eye. It is critical to hold the probe near
the tip, not at the hand piece, to avoid breakage.
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