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ORIGINAL STUDY
Glaucoma Tube Shunt Implantation Through the Ciliary
Sulcus in Pseudophakic Eyes With High Risk of
Corneal Decompensation
Asher Weiner, MD,*w z Aaron D. Cohn, MD,* Mamtha Balasubramaniam, MS,y
and Adam J. WeinerJ
Purpose: To summarize our clinical experience with implanting
Baerveldt glaucoma tube shunts through the ciliary sulcus in eyes
with a posterior chamber intraocular lens and shallow anterior
chambers, corneal transplants, guttata or edema.
Patients and Methods:
mized noncomparative
postoperative corneal
included postoperative
and complications.
A retrospective interventional nonrandocase series. Main outcome measure was
status. Secondary outcome measures
intraocular pressure (IOP), visual acuity
Key Words: tube shunt implantation, ciliary sulcus, corneal
decompensation, glaucoma surgery, intraocular pressure
(J Glaucoma 2010;19:405–411)
T
Conclusions: Although previously published studies demonstrated a
significant risk of corneal decompensation after angle or pars plana
tube implantation, our clinical experience suggests that ciliary
sulcus tube implantation in eyes with a posterior chamber
intraocular lens is a safe and effective procedure even in eyes with
high risk of corneal decompensation.
ube shunt implantation is an effective means to reduce
intraocular pressure (IOP) in eyes with uncontrolled
glaucoma. However, previous studies demonstrated a
significant risk of corneal decompensation after tube shunt
implantation through the irido-corneal angle1–7 (Fig. 1)
and a risk of both corneal decompensation and significant
posterior segment complications after implantation
through the pars plana.1,5,8–11 Tube insertion through the
ciliary sulcus has previously been advocated to protect
corneal transplants after tube implantation in 2 studies.12,13
In these studies combined, 6 corneal transplants remained
clear during a 16 to 36 month follow-up period. Eight eyes
with no corneal transplants were also described,12,14,15
bringing the total number of eyes detailed in the literature
with ciliary tube insertion to 14.
We have been inserting tubes through the ciliary sulcus
since 2002 in an attempt to protect the corneal endothelium
in eyes with a posterior chamber intraocular lens (PCIOL)
with shallow anterior chambers, corneal transplants,
corneal guttata or corneal edema. This paper is a summary
Received for publication February 22, 2009; accepted August 23, 2009.
From the *Beaumont Eye Institute; yBeaumont Research Institute,
William Beaumont Hospital, Royal Oak; wEye Research Institute,
Oakland University, Rochester; zAssociated Vision Consultants,
Southfield; and JUndergraduate, University of Michigan, AnnArbor, Michigan.
Financial Disclosure: All authors certify that any affiliations with or
involvement in any organization or entity with a direct financial
interest in the subject matter or materials discussed in the
manuscript (eg, employment, consultancies, stock ownership,
honoraria, and expert testimony) are disclosed as follows: Asher
Weiner, MD: consultant/speaker: Pfizer Ophthalmics, Allergan
and Alcon; not relevant to this study. Aaron D. Cohn, MD: None,
Mamtha Balasubramaniam, MS: None. Adam J. Weiner: None.
No research or project support has been received. All investigators had
full access to all the data in the study and take responsibility for the
integrity of the data and the accuracy of the data analysis.
Previous presentations: This study was presented in part at the
American Glaucoma Society annual meeting, Washington DC,
from March 7 to March 9, 2008 and at the Association for Research
in Vision and Ophthalmology (ARVO) annual meeting, Fort
Lauderdale, FL, from April 27 to May 1, 2008.
Reprints: Asher Weiner, MD, Associated Vision Consultants, 29275
Northwestern Highway, Suite 200, Southfield, MI 48034 (e-mail:
[email protected]).
Copyright r 2010 by Lippincott Williams & Wilkins
DOI:10.1097/IJG.0b013e3181bdb52d
FIGURE 1. Localized corneal edema in the area of a tube shunt
(T; black arrow) implanted through the anterior chamber angle,
too close to the cornea.
Results: Thirty-six eyes of 32 patients were identified through chart
review. Follow-up period was 21.8 ± 16.6 months (mean ±
standard deviation, range: 4.0 to 58.5 mo). At final visit, all 23
preoperative clear native corneas and 6 of 7 corneal transplants
remained clear. Thus, of the 30 preoperative clear corneas, only
1 decompensated. Preoperative IOP was 27.9 ± 11.8 mm Hg
(range: 12 to 59 mm Hg), reduced postoperatively to 10.1 ±
3.9 mm Hg (range: 2 to 21 mm Hg, P = 0.0001), a reduction of
58.2% ± 19.3% (range: 5.0% to 95.4%). Final IOP was Z5 and
r21 mm Hg in 33 of 36 eyes (91.7%). It was lowered by 30% or
more in 34 of 36 eyes (94.4%).
J Glaucoma
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TABLE 1. Patient Characteristics
Patient Characteristics (32 Patients)
Mean ± SD, Range
Age (years)
73.03 ± 11.79, 46-93
n (%)
15 (46.9)
Male
Ethnicity:
African American
White
Hispanic
Arab
Systemic hypertension
Cardiovascular events
NIDDM*
IDDMw
15 (46.9)
14 (43.8)
2 (6.2)
1 (3.1)
21 (65.6)
14 (43.8)
11 (34.4)
5 (15.6)
*Noninsulin dependent diabetes mellitus.
wInsulin dependent diabetes mellitus.
of our clinical experience in such eyes and it is the largest
series with the longest follow-up published to date.
PATIENTS AND METHODS
The Human Investigation Committee, William Beaumont Hospital, Royal Oak, Michigan approved this study.
We retrospectively identified 36 high-risk eyes of 32 patients
(Table 1) in a private glaucoma and retina referral practice
through a chart review of all tube shunt surgeries we
performed during the years from 2002 to 2007. We
considered these eyes to be of high-risk for corneal
decompensation after tube shunt implantation through
the anterior chamber angle if the tube would end up in close
proximity to the cornea in a shallow anterior chamber, if
the cornea demonstrated guttata or edema preoperatively,
or if the eye already had a corneal transplant.2–7,16
Inclusion criteria to our study included a tube implanted
through the ciliary sulcus, a PCIOL, and one or more of the
following: shallow anterior chamber, corneal transplant,
corneal guttata or corneal edema. Exclusion criteria
included a tube implanted through the anterior chamber
angle or the pars plana, phakia, aphakia, an anterior
chamber intraocular lens (ACIOL), or a normal native
cornea with none of the risk factors detailed above. In the
36 eyes identified, to avoid postoperative corneal decompensation and significant posterior segment complications,
the tube was inserted through the ciliary sulcus to rest
between the iris and the PCIOL, instead of through the
anterior chamber angle or the pars plana. Consequently,
the cornea was shielded from the tube by the iris with only
the distal end of the tube emerging from behind the iris at
the pupil margin (Fig. 2), resting as far as possible from the
cornea (Fig. 3). All tube shunts were implanted by a single
surgeon (A. W.) in eyes with uncontrolled glaucoma
refractory to medical therapy, most of which had previous
failed glaucoma procedures (Table 2).
FIGURE 2. Tube shunt (T; white arrow) implanted through the
ciliary sulcus, mostly shielded from the cornea by the iris, in an
eye with a corneal transplant. The anterior chamber was too
shallow (double-headed arrow) to allow for cornea-safe implantation of a tube through the angle.
A single-stage procedure was performed. A conjunctival and tenon’s capsule incision was made between
corresponding recti muscles, 7-8 mm from the limbus. A
Baerveldt-350 tube shunt (Advanced Medical Optics, Santa
Ana, CA) was implanted in all eyes, with a ‘‘rip-cord’’ valve
consisting of intraluminal 5-0 nylon suture (Ethicon,
Piscataway, NJ), and a 6-0 Vicryl suture (Ethicon, Piscataway, NJ) tied tightly around the tube 1 mm from the plate,
thereby occluding the tube to prevent early postoperative
hypotony. The 5-0 nylon suture was left lying under the
conjunctiva and Tenon’s capsule extending to the inferior
limbal area for future removal in the office. The shunt plate
was placed under the corresponding recti muscles and
Surgical Procedure and Postoperative Care
In all cases, steroid and antibiotic eye drops were used
4 times daily starting 3 days before surgery. Peribulbar
anesthesia was used and supplemental intraoperative subtenon anesthesia was added as needed. The superotemporal
quadrant was used in 32 of 36 eyes (89%), the superonasal
quadrant in 2 eyes (5.5%), and the inferotemporal quadrant
in the remaining 2 eyes (5.5%).
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FIGURE 3. Ultrasound biomicroscopy of a tube shunt (T; white
arrow) implanted through the ciliary sulcus, seen between the iris
(I; white arrow) and the posterior chamber IOL, as far as possible
from the cornea (C; white arrow). A/C indicates anterior
chamber; IOL, intraocular lens.
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Ciliary Sulcus Glaucoma Tube Shunt Implantation
TABLE 2. Eye Characteristics
Preoperative Eye Characteristics (36
Eyes)
Glaucoma type:
Chronic angle closure
Primary open angle
Uveitic
Neovascular
Pseudoexfoliative
Pigmentary
Right eye
Shallow anterior chamber
Corneal guttata
Corneal transplant (all clear)
Edematous native cornea
Previous trabeculectomy
Previous laser trabeculoplasty
Previous cyclophotocoagulation
IOP (mm Hg)
Eye medications
Corneal thickness (mm)
Postoperative Eye Characteristics
Length of follow-up (months)
Final visit IOP (mm Hg)
Final visit eye medications
Postoperative complications
Early hyphema
Flat anterior chamber*
Serous choroidal detachment
Corneal failurew
n (%)
17 (47.2)
10 (27.8)
3 (8.3)
3 (8.3)
2 (5.6)
1 (2.8)
13 (36.1)
25 (69.4)
12 (33.3)
7 (19.4)
6 (16.7)
24 (66.7)
25 (69.4)
5 (13.9)
Mean ± SD, range, n
27.9 ± 11.8, 12-59, 36
4.1 ± 1.1, 2-6, 36
553.52 ± 78.39, 415-872, 29
Mean ± SD, range, n
21.8 ± 16.6, 4.0-58.5, 36
10.1 ± 3.9, 2-21, 36
1.9 ± 1.7, 0-5, 36
n/total (%)
10/36 (27.8)
3/36 (8.3)
7/36 (19.4)
1/30 (3.3)
*Requiring viscoelastic injection into the anterior chamber.
wDefined as decompensation of a cornea, native or transplant, that was
clear preoperatively.
IOP indicates intraocular pressure.
fixated to bare sclera, 9 mm from the limbus, with 2 interrupted 8-0 nylon sutures (Ethicon, Piscataway, NJ).
A 15-degree supersharp knife (Alcon Laboratories,
Inc, Fort Worth, TX) was used to create a limbal
inferotemporal paracentesis, through which Viscoat (Alcon
Laboratories, Inc, Fort Worth, TX) was injected into the
anterior chamber, with care to maintain low normal IOP
throughout the procedure. All tubes were then trimmed to
appropriate length with an anterior facing bevel.
Additional Viscoat was injected between the iris and
the PCIOL in the location chosen for tube insertion. A 23gauge needle, mounted onto the Viscoat syringe, was used
to create a shelved scleral tunnel, beginning 1.5 mm to 2 mm
from the limbus, directed to enter the space between the iris
and the PCIOL. During needle insertion, small amounts of
Viscoat were injected to identify the location of the needle
tip behind the iris and to help keep the tip clear of the iris,
lens capsule, and the IOL. The tube was then inserted
through the scleral tunnel and advanced until its tip
emerged from behind the iris, clearing the nondilated pupil
margin to prevent later occlusion by iris tissue (Fig. 3). In
eyes with a small pupil, a small sector iridectomy (Fig. 4)
was performed at the tube location with fine long-blade
capsular scissors (Katena Products, Inc, Denville, NJ)
inserted through the limbal paracentesis. The small sector
iridectomy was performed to allow keeping the tube away
from the center of a small pupil where it could interfere
with retinal evaluations and photocoagulation, yet allowing
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FIGURE 4. Tube shunt (T; white arrow) implanted through the
ciliary sulcus, mostly shielded from the cornea by the iris, with
only its distal end visible through a small sector iridectomy (SI;
double white arrow).
it to clear iris tissue. Only 5 patients (5 eyes) in our current
series underwent sector iridectomy.
The tubes were fixated to sclera 1 mm from their
scleral entry with a triple-loop 10-0 nylon suture (Ethicon,
Piscataway, NJ) and a single loop 10-0 nylon suture several
millimeters more posteriorly. Two to three 1 mm fenestrations were made into the side of the tube using a 15-degree
supersharp knife (Alcon Laboratories, Inc, Fort Worth,
TX) to allow for early postoperative IOP control. Aqueous
humor was observed to slowly egress through these
fenestrations. All tubes were covered by a 5 8 mm Tutoplast scleral graft (IOP Inc, Costa Mesa, CA), first soaked
in gentamycin solution, then trimmed to appropriate size
and fixated to sclera with 2 interrupted 10-0 nylon sutures
with the knots buried under the patch.
The initial conjunctival and Tenon’s incision was then
closed in 2 layers using an 8-0 Vicryl suture (Ethicon,
Piscataway, NJ), closing Tenon’s capsule in a runninglocking fashion and the conjunctiva in a running-nonlocking watertight fashion. Viscoat was then irrigated out of the
anterior chamber through the paracentesis using balanced
salt solution (Alcon Laboratories, Inc, Fort Worth, TX),
maintaining a deep anterior chamber and a low normal
IOP. Then, a 1 mL of an antibiotic and steroid mixture was
injected into the inferior fornix, a combination antibioticsteroid ointment was instilled onto the cornea, and the eye
was double-patched and shielded.
Postoperative therapy included antibiotic eye drops
4 times daily, steroid drops 4 to 6 times daily with a slow
taper, and a combination antibiotic-steroid ointment
administered nightly with a shield. This regimen was continued until the surgical wound appeared well closed and
vascularized, usually within 4 to 6 weeks. The intraluminal
5-0 nylon suture was removed at the slit lamp usually within
4 to 8 weeks postoperatively by pulling it through a 1 mm
conjunctival and Tenon’s incision at the location of the tip of
the 5-0 nylon suture. IOP lowering medications were used
postoperatively as needed, and the final desired IOP was
usually achieved and maintained within the first 6 weeks
postoperatively, with or without medications.
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Corneal Status Definitions
We defined a native cornea as a natural cornea without
any past corneal procedure. Corneal transplant refers in
our study only to a full thickness transplant. We defined
corneal decompensation as a thickened cornea with
endothelial striae and stromal opacification sufficient
to obscure some or all details of the anterior chamber
structures. Corneal edema was defined as a thickened
cornea with endothelial striae but with a clear view of the
anterior chamber structures and no stromal opacification.
Surgical Success
The primary definition of surgical success in our study
was lack of postoperative corneal edema or decompensation, as defined above, in a preoperative clear cornea, native
or transplant.
The main secondary measure of surgical success was
postoperative IOP control. This was defined as final visit
IOP Z5 mm Hg and r21 mm Hg, and reduced by at least
30% compared with preoperative IOP, with or without
IOP-lowering medications.
FIGURE 5. Kaplan-Meier survival curve for time (months) to
surgical failure due to corneal failure (1 eye), defined as
postoperative decompensation of a presurgery clear cornea,
native or transplant. Tick marks represent censored observations,
that is, patients with no failure at the end of their follow-up.
Statistical Methods
Paired t test was used to compare parameters such
as preoperative and postoperative IOP. Cox proportional
hazards regression, with results based on the Wald w2 test,
was used to assess potential predictors for surgical failure.
Kaplan-Meier actuarial rates of survival were determined
to assess time to failure. Only 1 eye of each patient was used
in the Cox proportional hazard regression and the KaplanMeier survival analyses. P-values less than an a of 0.05
(Probability of Type I Error) were considered statistically
significant. Statistical analysis was performed using the SAS
System for Windows version 9.1.3, Service Pack 2.
RESULTS
Thirty-six eyes of 32 patients were identified. Followup period was 21.8 ± 16.6 months (mean ± SD, range, 4.0
to 58.5 mo). Tables 1 and 2 show pertinent patient and eye
characteristics.
Surgical Results
Postoperative Corneal Decompensation (Table 3)
At final visit, all 23 preoperative clear native corneas,
and 6 of 7 preoperative clear corneal transplants remained
clear. Thus, of the 30 preoperative clear corneas, only 1
TABLE 3. Corneal Status Before and After Sulcus Tube Shunt
Implantation (36 eyes)
Posttube Corneal Status
at Final Visit
Pretube Corneal Status
Clear native
Edematous native
Clear corneal transplant
Clear cornea
(native or transplant)
Clear
23
6
7
30
23
2
6*
31
Edema
Decompensated
3
1
1w
*Length of follow-up (months): 8.8, 17.6, 29.1, 42.0, 46.9, and 53.7.
wLength of follow-up to decompensation (months): 5.2.
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decompensated postoperatively and thus met the criteria of
surgical failure because of corneal status. On the basis of
Kaplan-Meier survival analysis, the corresponding actuarial success rate was 0.9643 (only 1 failure) with a length
of follow-up of 5.2 months to failure (Fig. 5). Of the 6
preoperative edematous corneas, 2 cleared, 1 decompensated, and 3 remained unchanged (Table 3).
Postoperative-IOP Control
Preoperative IOP was 27.9 ± 11.8 mm Hg (mean ± SD,
range: 12 to 59 mm Hg). It was significantly reduced to final
visit IOP of 10.1 ± 3.9 mm Hg (mean ± SD, range: 2 to
21 mm Hg, P = 0.0001), a reduction of 58.2% ± 19.3%,
(mean ± SD, range: 5.0% to 95.4%). Final visit IOP was Z5
and r21 mm Hg in 33 of 36 eyes (91.7%), and it was lowered
by 30% or more in 34 of 36 eyes (94.4%). Five eyes met the
criteria of surgical failure because of the postoperative-IOP
control. At final visit, 3 of them had IOP below 5 mm Hg,
and the 2 additional failures had an IOP reduction of less
than 30%. On the basis of Kaplan-Meier survival analysis,
the corresponding Kaplan-Meier actuarial success rate was
0.66 with a length of follow-up to failure of 38.49 ± 3.04
months (mean ± SD, Fig. 6).
On the basis of Cox proportional hazard regression
analysis there was no significant difference in time to failure
due to any of the variables studied such as age, sex,
ethnicity, and systemic or ocular conditions, shown in
Tables 1 and 2.
The number of IOP lowering medications (36 eyes)
was significantly reduced from 4.1 ± 1.1 (mean ± SD,
range: 2 to 6) to 1.9 ± 1.7 (mean ± SD, range: 0 to 5,
P = 0.0001) postoperatively. Nine (25.0%) of the 36 eyes
required no IOP lowering medications at final visit whereas
8 (22.2%), 7 (19.4%), 6 (16.7%), 2 (5.6%), and 4 (11.1%)
eyes required 1, 2, 3, 4, and 5 medications, respectively.
Visual Acuity
For the purpose of visual acuity calculation, count
finger vision equivalent was 20/800, hand motion equivalent was 20/1600, and light perception equivalent was
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Volume 19, Number 6, August 2010
FIGURE 6. Kaplan-Meier survival curve for time (months) to
surgical failure due to postoperative IOP control, defined as final
visit IOP <5 mm Hg (3 eyes) or >21 mm Hg (0 eyes) or a % IOP
reduction of less than 30% at last visit (2 eyes). Tick marks
represent censored observations, that is, patients with no failure
at the end of their follow-up. IOP indicates intraocular pressure.
20/3200. Preoperative visual acuity was 0.22 ± 0.21
(mean ± SD, range: 0.005 to 1.0) and postoperative
acuity was 0.20 ± 0.20 (mean ± SD, range: 0.005 to 0.8).
LogMAR (minimal angle of resolution) visual acuity did
not change significantly after surgery (P = 0.43).
Postoperative Hyphema
Of the 36 eyes, 10 (27.8%) had early postoperative
small (0.5 to 2.0 mm) hyphema that cleared within 1 to 2
weeks except for 1 eye with neovascular glaucoma and
extensive iris rubeosis that required 1 anterior chamber
washout. Only 2 of the 10 eyes with hyphema underwent
sector iridectomy during tube shunt implantation.
Other Postoperative Complications
Three eyes (8.3%) had a flat anterior chamber that
required 1 viscoelastic injection and 7 eyes (19.4%) had
serous choroidal detachments that resolved spontaneously.
There were no other posterior segment complications.
DISCUSSION
In this summary of our clinical experience, we retrospectively evaluated the implantation of glaucoma tube
shunts through the ciliary sulcus, to rest between the iris
and the PCIOL, in eyes with shallow anterior chambers,
corneal transplants, corneal guttata, or corneal edema. In
such eyes, tube shunt implantation through the iridocorneal angle or the pars plana has been shown to cause a
high rate of corneal decompensation.1–7,16 Corneal transplant failure rate was reported to range from 30.8% to as
high as 88.9% in eyes with tubes inserted through the
angle,2–7,16 59% in eyes with tubes inserted through the
pars plana,8 and as high as 70% in a study with mixed angle
and pars plana tubes.1 Native (nontransplant) corneal
decompensation rate was reported to range from 9.7% to
20.75% in angle tubes,2,4,6,17 and 29.4% in pars plana
tubes.9 Implantation through the pars plana has also lead
to significant posterior segment complications.1,5,8–11 In
contrast, our clinical experience suggests that implanting
Baerveldt-350 tube shunts through the ciliary sulcus in eyes
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Ciliary Sulcus Glaucoma Tube Shunt Implantation
with PCIOLs lowers the risk of both corneal decompensation and significant posterior segment complications.
Despite the fact that our tubes were implanted in eyes with
high risk of corneal decompensation, only 1 preoperative
clear cornea decompensated postoperatively (Fig. 5). This
cornea was a second corneal transplant in an eye with a
history of severe trauma, several surgeries, and a previously
failed corneal transplant that was replaced before the tube
shunt implantation. The other 2 corneal failures in our
study were already partially decompensated before the tube
implantation. Interestingly, 2 other eyes with preoperative
corneal edema cleared after tube insertion through the
sulcus, most likely secondary to the postoperative reduction
in IOP. All other preoperative clear corneas, native or
transplant, remained clear postoperatively.
Our results support those of 2 previous smaller studies
suggesting that tube insertion through the sulcus is safe,
effective, and lowers the risk of corneal decompensation.12,13 Our study nearly quadruples the number of such
eyes described in the literature, and doubles the number of
similar eyes with corneal transplants. It also expands their
follow-up period to up to 53.7 months. Thus, it further
strengthens the impression that tube insertion through the
ciliary sulcus may be safer than through the anterior
chamber angle or the pars plana in eyes with PCIOLs.
Several mechanisms for corneal damage after tube
shunt implantation may be considered. Continuous corneal
endothelial damage may occur because of a constant
cornea-tube touch such as when the tube is implanted
through the angle too close to the cornea. In such eyes, we
have first observed the development of local corneal edema
around the tube (Fig. 1), followed even years later by
diffuse corneal edema and decompensation. Intermittent
corneal endothelial damage may also occur when the tube
is implanted through the angle. In such cases the tube,
although not continuously touching the cornea, is positioned close enough to the cornea to allow for intermittent
cornea-tube touch during eye rubbing, squeezing, and
perhaps even blinking. In contrast, when implanting a tube
through the ciliary sulcus to rest between the iris and the
PCIOL, the cornea is shielded from the tube which lies
against the PCIOL as far away from the cornea as possible
(Fig. 3). This most likely prevents cornea-tube touch under
any normal circumstances.
However, corneal decompensation may also occur
without any cornea-tube touch by several mechanisms.
Periods of increased IOP before and after tube implantation
may lead to an accelerated rate of corneal endothelial cell
loss.18,19 The chronic use of topical glaucoma medications
before and after tube implantation may be a significant risk
factor for corneal graft failure by rejection, endothelial
decompensation without rejection, and ocular surface
disease.20 In fact, the chronic use of topical glaucoma
medications alone, even with no tube shunt implantation,
was demonstrated to triple the rate of corneal transplant
failure, up to 47.1%.1 Other mechanisms are the continued
decline in endothelial cell count of corneal grafts in eyes
with no tubes,21 and the additional age-related normal
decline in corneal endothelial cell count.22 The previous use
of Mitomycin C in trabeculectomy surgery may be another
risk factor for corneal endothelial damage;23,24 many eyes
undergoing tube shunt implantation have already had
several surgeries including trabeculectomy with Mitomycin
C. Yet another mechanism is the known accelerated rate of
corneal endothelial cell loss after any ocular surgery.25,26
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The additional surgical trauma from the vitrectomy
procedure, in addition to that from the tube implantation,
may be the underlying cause of the significant rate of
corneal failure after pars plana tube insertion.
In conclusion, in view of all these possible contributing
mechanisms, corneal decompensation after tube shunt
implantation cannot be attributed exclusively to the mere
presence of a tube in the eye, whether anterior or posterior
to the iris.
Further, whereas insertion of tube shunts through the
pars plana has been advocated as a means to reduce the
frequency of corneal decompensation after tube shunt
implantation, not only does this method of tube insertion
not seem to reduce the rate of corneal failure,1,8,27 it is also
costly and often carries the risk of significant posterior
segment complications. It often necessitates posterior
vitrectomy in cooperation with a retinal surgeon resulting
in significant costs and logistics, and it can lead to tube
blockage by residual vitreous in 3% to 15.4% of the
eyes,8,28,29 epiretinal membrane formation in 9%,8 retinal
detachment in 6% to 20%,8,10,11 and even blindness in as
many as 15% of the eyes.30 In contrast, the only posterior
segment complication in our study was a self-limited serous
choroidal detachment. Similarly, significant posterior segment complications were not reported in the previous
studies on sulcus inserted tubes.12,13 Thus, it appears that
tube shunt implantation through the ciliary sulcus may help
avoid significant posterior segment complications compared with pars plana insertion.
In addition to its apparent safety, our study demonstrates that sulcus tube implantation is also effective in
controlling IOP. Postoperative final IOP was reduced by
30% or more in 34 of 36 eyes (94.4%); the remaining 2 eyes
were considered surgical failures (Fig. 6). Final IOP was
between 5 and 21 mm Hg in 33 of 36 eyes (91.7%). The
other 3 eyes were considered surgical failures since their
final IOP was below 5 mm Hg (Fig. 6). One was a case of
severe ocular ischemia with neovascular glaucoma secondary to a familial hypercoagulative condition and later
ciliary body shut down; IOP remained very low even after
the tube was eventually removed. The other 2 eyes had endstage glaucoma where a very low IOP was targeted and did
not affect visual acuity.
Further, the number of IOP lowering medications in
our study was significantly reduced postoperatively, with
9 eyes (25%) requiring no IOP lowering medications at the
end of follow-up.
We have observed several complications during the
postoperative period (Table 2). Ten eyes (27.8%) had
early postoperative small (0.5 mm to 2.0 mm) hyphema
that cleared within 1 to 2 weeks except for 1 eye with
neovascular glaucoma and extensive iris rubeosis that
required anterior chamber washout. This rate of hyphema
was higher than that reported in studies of tubes inserted
through the angle or the pars plana (8% to 16.9%).4,16,17,31
This difference may be explained by the more vascularized
tissues of the ciliary sulcus compared with the angle or pars
plana. However, none of these cases in our study resulted in
tube blockage or long-term complications. Sector iridectomy did not seem to be a major cause of hyphema as the
latter was present in only 2 of the 5 eyes that underwent
sector iridectomy and 8 of the 10 eyes with hyphema did not
have sector iridectomy. Self-limited serous choroidal
detachment occurred in 7 eyes (19.4%) in our study; this
rate was not different than that reported in studies of angle
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Volume 19, Number 6, August 2010
or pars plana inserted tube shunts (7% to 23%).4,17,27,32–34
None of these or other complications listed in Table 2 were
of any long-term consequence. Furthermore, with our
described technique of tube insertion through the sulcus, we
have not observed any cases of IOL dislocation, pigment
dispersion, tube blockage by iris, or significant visual loss.
Our study is limited by several factors. It is a
retrospective chart review and a summary of our clinical
experience rather than a randomized controlled prospective
study, and the number of eyes studied was relatively small,
particularly the number of eyes with corneal transplants.
Also, only some types of glaucoma were represented in our
study (Table 2); thus, the safety of tube implantation
through the sulcus was not evaluated in all types of
glaucoma. In addition, half of our patients were diabetic
(Table 2). This is most likely the result of the relatively high
proportion of patients with diabetes in our private glaucoma and retina referral practice. It is our speculation that
this bias has not affected our results.
Despite our study limitations, we believe that our
clinical experience further supports the notion that tube
implantation through the ciliary sulcus in eyes with PCIOLs
is a safe and effective procedure, and may be the preferred
mode of tube implantation in such eyes, especially in those
with high risk of corneal decompensation.
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