This study evaluated the use of multiple trabecular micro-bypass stents combined with cataract surgery in 53 eyes of patients with open-angle glaucoma and cataract. The study found that using 2 or 3 micro-bypass stents led to a mean postoperative intraocular pressure of 14.3 mm Hg, significantly lower than the preoperative pressure of 18.0 mm Hg. Patients were also able to achieve their target pressure control with significantly fewer glaucoma medications, with a 74% reduction in the mean number of medications used from 2.7 preoperatively to 0.7 at the 1-year follow up. Patients who received 3 stents were on significantly fewer medications than those who received

1. ARTICLE
Using multiple trabecular micro-bypass stents
in cataract patients to treat open-angle glaucoma
Graham W. Belovay, MD, Abdulla Naqi, MD, Brian J. Chan, MD,
Mahmoud Rateb, MD, Iqbal Ike K. Ahmed, MD
PURPOSE: To evaluate the efficacy of multiple trabecular micro-bypass stents combined with
cataract surgery in patients with open-angle glaucoma (OAG) and cataract.
SETTING: Private practice, Mississauga, Ontario, Canada.
DESIGN: Comparative case series.
METHODS: Eyes with OAG had implantation of 2 or 3 micro-bypass stents with concurrent cataract
surgery and follow-up through 1 year. Efficacy measures were intraocular pressure (IOP) and
topical ocular hypotensive medication use. Safety assessment included complications and
corrected distance visual acuity (CDVA).
RESULTS: The study comprised 53 eyes (47 patients); 28 had implantation of 2 stents and 25 had
implantation of 3 stents. The overall mean 1-year postoperative IOP was 14.3 mm Hg, which was
significantly lower than preoperative IOP overall and in each group (P<.001). The target IOP was
achieved in a significantly higher proportion of eyes at 1 year versus preoperatively (77% versus
43%; P<.001). Overall, 83% of eyes had a decrease in topical ocular hypotensive medication at
1 year from preoperatively, with a 74% decrease in the mean number of medications (from
2.7 to 0.7) at 1 year (P<.001). The 3-stent group was on significantly fewer medications than the
2-stent group at 1 year (0.4 versus 1.0; PZ.04).
CONCLUSIONS: Using multiple micro-bypass stents with concurrent cataract surgery led to a mean
postoperative IOP of less than 15 mm Hg and allowed patients to achieve target pressure control
with significantly fewer medications through 1 year.
Financial Disclosure: Dr. Ahmed is a consultant to Glaukos Corp. No other author has a financial or
proprietary interest in any material or method mentioned.
J Cataract Refract Surg 2012; 38:1911–1917 Q 2012 ASCRS and ESCRS
Open-angle glaucoma (OAG) can be managed in sev- complications, including infection, corneal decompen-
eral ways depending on the target intraocular pressure sation, choroidal hemorrhage, hypotony, diplopia, and
(IOP), medication use, severity of glaucoma, quality of vision loss.1–7 Thus, despite their effective control of
life, surgeon experience, and the surgical techniques IOP, they should not be considered benign operations.
available. In general, newly diagnosed glaucoma is In the case of mild to moderate glaucoma and
managed with medical therapy, possibly in combina- clinically significant cataract, less invasive surgical
tion with laser trabeculoplasty. It is typically not until alternatives, such as microinvasive surgeries, can be
the later stages of the disease when the patient is on performed in conjunction with cataract surgery. The
maximum medical therapy that ab externo filtering use of less invasive treatments to reduce IOP and
procedures are considered. glaucoma medications is a desirable approach to
In the case of glaucoma and visually clinically signif- treating glaucoma, especially if this approach does
icant cataract, combined cataract and glaucoma proce- not limit other options in the future.
dures have been shown to not only lower IOP but to The iStent implant (Glaukos Corp.) is a trabecular
also reduce the number of glaucoma medications.1–3 bypass device. It is the first of a class of new ab interno
Unfortunately, traditional ab externo glaucoma devices that enables minimally invasive glaucoma
surgical procedures (eg, trabeculectomy, tubes, deep surgery. Several studies have shown the effectiveness
sclerectomy) are associated with significant risks and and safety of implanting this stent in eyes with mild to
Q 2012 ASCRS and ESCRS 0886-3350/$ - see front matter 1911
Published by Elsevier Inc. http://dx.doi.org/10.1016/j.jcrs.2012.07.017

2. 1912 MULTIPLE TRABECULAR MICRO-BYPASS STENTS
moderate glaucoma to achieve this goal. Fea8 and Preoperatively, demographic information (age, sex, and
Samuelson et al.9 compared phacoemulsification race), ocular history (including type of glaucoma), glaucoma
medications, and results from a recent visual field were
with and without stent implantation and found that
recorded. The preoperative ocular examination included
the combined surgery was more effective at control- Snellen corrected distance visual acuity (CDVA), IOP
ling IOP than cataract surgery alone; the safety profiles (Goldmann applanation tonometry [GAT]), cup-to-disc ratio,
of both groups were similar. Spiegel et al.10,11,A stud- anterior chamber angle (Shaeffer grade), and lens opacity grade
ied stent implantation with concurrent cataract (Lens Opacity Classification III15). Target IOP and the stage of
glaucoma were determined using the Canadian Ophthalmo-
surgery in glaucoma patients and found effective
logical Society evidence-based clinical practice guidelines for
IOP control through 24 months (16.9 mm Hg versus the management of glaucoma in the adult eye.16 Patients
21.9 mm Hg preoperatively). Also, medication use with a remote history of angle-closure glaucoma requiring laser
was reduced (0.4 versus 1.4 preoperatively). None of peripheral iridotomy and open angles at the time of surgery
these studies reports major surgical complications. were classified as mixed mechanism. Ocular hypotensive
medications were not discontinued before surgery.
Earlier work12 suggests that more advanced OAG
Using the technique described by Spiegel et al.,10 the same
patients may require postoperative target pressures surgeon (I.I.K.A.) implanted 2 or 3 iStents in the eye after
of 15 mm Hg or less to prevent further glaucomatous phacoemulsification. The stents were inserted in the nasal re-
progression. Studies of the trabecular bypass stent by gion of the trabecular meshwork separated by 1 to 2 clock
Zhou and Smedley13 and Bahler14 addressed this hours. Eyes requiring greater IOP control (ie, to achieve the
target IOP) as determined by the operating surgeon received
lower threshold. They established a theoretical in vitro
3 stents instead of 2 stents. Intraoperatively, the type of intra-
perfusion model that predicted that multiple ocular lens, the number of stents implanted, and the compli-
trabecular stents may increase facility of outflow and cations were recorded.
reduce IOP versus a single implant. Bahler et al.14 Postoperatively, patients were seen at 1 day, 1 week, and
found that subsequent placement of a second stent 1, 3, 6, and 12 months. Snellen visual acuity, IOP (with GAT),
glaucoma medications, stent placement using gonioscopy,
reduced the mean IOP by an additional 3.6 mm Hg
and complications were assessed at these visits by the exam-
in 7 of 9 enucleated cadaver eyes. ining physician. The examiners were not masked to the num-
The current study evaluated the effects of multiple ber of stents. The number of ocular hypotensive medications
trabecular micro-bypass stents in combination with was reduced gradually based on the postoperative IOP tar-
cataract surgery on IOP and glaucoma medication get in each case.
Statistical analyses were performed using SPSS software
use in patients with OAG and concurrent cataract.
(version 15, International Business Machines Corp.) in an
intent-to-treat analysis. A paired t test was used to determine
the significance of the change in IOP and glaucoma medica-
PATIENTS AND METHODS tions from baseline to 12 months. A 2-sample t test was used
to compare the IOP and glaucoma medications between each
This was an open-label nonrandomized prospective single- time point and each stent group. A Mann-Whitney test was
center series of eyes with OAG that had implantation of performed to compare outcomes between the 2-stent group
2 or 3 trabecular micro-bypass stents with concurrent cata- and the 3-stent group. Demographic data were compared be-
ract surgery. Key inclusion criteria were visually significant tween groups using a 2-sample t test or Fisher exact test. Sig-
cataract, IOP that was not well controlled on medication or nificance was set at 5%.
was well controlled but with a substantial (R3) medication
burden, and follow-up through 12 months postoperatively.
Ethics approval was obtained from IRB Services, Ltd., Au-
rora, Ontario, Canada, and all patients provided informed RESULTS
consent. The study enrolled 53 eyes of 47 patients. Table 1A
shows the patients’ demographics and Table 1B, the
Submitted: November 29, 2011. preoperative characteristics. All eyes had cataract
Final revision submitted: July 3, 2012. requiring surgery. Glaucoma diagnoses at time of sur-
Accepted: July 6, 2012. gery included primary OAG, pseudoexfoliative, and
mixed mechanism. Previous glaucoma surgeries
From the University of Toronto (Belovay, Naqi, Rateb, Ahmed),
included laser peripheral iridotomy, argon laser trabe-
Toronto, Ontario and McMaster University (Chan), Hamilton, Ontario,
Canada; University of Utah (Ahmed), Salt Lake City, Utah, USA.
culoplasty (ALT), and selective laser trabeculoplasty
(SLT). Eight eyes had 2 procedures (laser peripheral
Presented in part at the American Glaucoma Society Meeting, San iridotomy and ALT, n Z 1; laser peripheral iridotomy
Diego, California, USA, March 2010, and at the ASCRS Symposium and SLT, n Z 4; ALT and SLT, n Z 3). Those with laser
on Cataract, IOL and Refractive Surgery, Boston, Massachusetts, peripheral iridotomies, with the exception of the mixed-
USA April 2010. mechanism patients, had the procedures performed by
Corresponding author: Iqbal Ike K. Ahmed, MD, Credit Valley their referring physicians for reasons unknown. No eye
EyeCare, 3200 Erin Mills Parkway, Unit 1, Mississauga, Ontario, had a history of trabeculectomy or shunt implantation.
L5L 1W8, Canada. E-mail: ike.ahmed@utoronto.ca. Approximately half the eyes had a preoperative CDVA
J CATARACT REFRACT SURG - VOL 38, NOVEMBER 2012

3. MULTIPLE TRABECULAR MICRO-BYPASS STENTS 1913
Table 1A. Demographics.
Parameter Overall (N Z 47)* 2-Stent Group (n Z 26) 3-Stent Group (n Z 23) P Value
Mean age (y) G SD 77.2 G 7.4 78.8 G 7.0 75.0 G 7.3 .07†
Sex, n (%) .54z
Male 14 (30) 7 (27) 9 (39)
Female 33 (70) 19 (73) 14 (61)
Race, n (%) .43x
White 29 (62) 18 (69) 11 (48)
Black 7 (15) 4 (15) 4 (17)
South Asian 7 (15) 2 (8) 5 (22)
Far East Asian 4 (8) 2 (8) 3 (13)
*Two patients received 2 stents in 1 eye and 3 stents in the other eye
†
Two-sample t test
z
Fisher exact test
x
Fisher exact test with Monte Carlo simulation
of 20/50 to 20/100, with the remainder having a CDVA Intraocular Pressure and Medications by Stent Group
of 20/40 or better or 20/200 or worse. Eight eyes had The 1-year IOP was significantly lower than the
mild glaucoma, 23 had moderate glaucoma, and 22 preoperative IOP in the 2-stent group (mean
had advanced glaucoma. 13.8 mm Hg postoperatively) and the 3-stent group
Of the 53 eyes, 28 had implantation of 2 stents and (mean 14.8 mm Hg postoperatively) (both P!.001)
25 had implantation of 3 stents. Forty-one patients (Figure 2). There was no significant difference in IOP
(87%) had 2 or 3 stents implanted in 1 eye only. Two reduction between the 2 groups (PZ.78). Twenty-
patients received 3 stents bilaterally, 2 received 2 stents one eyes (75%) in the 2-stent group achieved a 1-year
bilaterally, and 2 received 2 stents in 1 eye and 3 stents postoperative IOP of 15 mm Hg or less. The IOP reduc-
in the other eye. tion was greater in the 3-stent group, with a mean
The mean preoperative medicated IOP was similar reduction of 3.9 mm Hg versus 3.5 mm Hg in the
between the 2-stent group and the 3-stent group. Over- 2-stent group (PZ.76). Target IOP was achieved by
all preoperatively, fewer than half the eyes were at the 20 eyes (71%) in the 2-stent group and 21 eyes (84%)
target IOP levels. in the 3-stent group. The mean number of topical ocu-
The mean number of preoperative medications was lar hypotensive medications significantly decreased to
similar between the 2-stent group and the 3-stent 1.0 medication and 0.4 medication, respectively, at
group. More eyes in the 3-stent group than in the 1 year (P!.001) (Figure 3), representing a 64% reduc-
2-stent group were taking 4 or more medications. tion in medications in the 2-stent group and 85%
reduction in the 3-stent group. The 3-stent group was
Overall Intraocular Pressure and Medications on significantly fewer medications at 1 year than the
Overall, the decrease in the mean IOP from preop- 2-stent group (PZ.04). At 1 year, medication use had
eratively (18.0 G 4.0 mm Hg) to 1 year postopera- been stopped in 13 eyes (46%) in the 2-stent group
tively (14.3 G 2.9 mm Hg) was statistically and 18 eyes (72%) in the 3-stent group.
significant (P!.001) (Figure 1). Thirty-seven eyes
(70%) achieved an IOP of 15 mm Hg or less at 1 Complications
year, and 41 eyes (77%) achieved the target IOP. The most common complication was blockage of
The mean overall number of topical ocular hypoten- the opening of the stent lumen, which occurred in
sive medications decreased significantly from 2.7 G 8 eyes in the early postoperative period. Stent block-
1.0 preoperatively to 0.7 G 1.1 medications at 1 age was successfully treated with a neodymium:YAG
year (P!.001) (Figure 1). The mean reduction at 1 laser or argon laser in 6 eyes and then repeated in 1 of
year was 2.0 G 1.4 medications, representing a 74% these eyes. Laser treatment was not performed in
reduction. Forty-four patients (83%) reduced the 2 eyes because of good IOP control with a second pat-
number of medications at 1 year, and 31 (59%) dis- ent stent in 1 eye and because the blockage was partial
continued use of all medications in the study eye. in 1 eye.
The remaining eyes ended up on 1 medication (13 One eye presented with small hyphema 1 day post-
[24%]) or 2 or 3 medications (3 [6%] and 5 [9%], re- operatively that resolved by 4 weeks postoperatively.
spectively); 1 eye was using 4 medications at 1 year. One of the stents in 1 eye was not seated well in the
J CATARACT REFRACT SURG - VOL 38, NOVEMBER 2012

4. 1914 MULTIPLE TRABECULAR MICRO-BYPASS STENTS
Table 1B. Preoperative characteristics.
Parameter Overall (N Z 53) 2-Stent Group (n Z 28) 3-Stent Group (n Z 25) P Value
Glaucoma, n (%)
Primary open angle 37 (70) 21 (75) 16 (64) .55*
Pseudoexfoliative 14 (26) 7 (25) 7 (28) 1.00*
Mixed mechanism 2 (4) 0 2 (8)
Other ocular conditions, n (%)
ARMD 2 (4) 4 (14) 0
High myopia 2 (4) 1 (4) 1 (5)
Suprasellar lesion (treated with radiation) 2 (4) 1 (4) 1 (5)
Branch vein occlusion 1 (2) 1 (4) 0
Diabetic retinopathy 1 (2) 0 1 (4)
ARMD scar 1 (2) 0 1 (4)
Optic nerve head drusen 1 (0) 1 (4) 0
Previous glaucoma procedures, n (%)
LPI 11 (21) 4 (14) 7 (28) .31*
ALT 9 (17) 6 (21) 3 (12) .47*
SLT 17 (32) 7 (25) 10 (40) .38*
O1 previous procedure 8 (15) 3 (11) 5 (20) .45*
Eye, n (%) .42*
Right 24 (45) 11 (39) 13 (52)
Left 29 (55) 17 (61) 12 (48)
CDVA, n (%) .76†
20/40 or better 14 (26) 6 (21) 8 (32)
20/50–20/100 26 (49) 15 (54) 11 (44)
20/200 or worse 13 (25) 7 (25) 6 (23)
Mean C:D ratio G SD 0.74 G 0.16 0.76 G 0.16 0.71 G 0.17 .23†
Mean Shaffer grade G SD 2.9 G 0.7 2.9 G 0.8 2.8 G 0.6 .93†
Visual field
Mean Deviation (dB) G SD À11.5 G 7.6 À12.6 G 7.1 À10.2 G 8.1 .24†
Mean pattern SD (dB) G SD 6.9 G 3.8 7.9 G 3.4 5.9 G 4.1 .06†
Intraocular pressure
Mean (mm Hg) G SD 18.0 G 4.0 17.3 G 4.0 18.6 G 4.0 .24†
!15 mm Hg, n (%) 11 (21) 6 (21) 5 (20)
15–18 mm Hg, n (%) 22 (42) 13 (46) 9 (36)
O18 mm Hg, n (%) 20 (38) 9 (32) 11 (44)
Target intraocular pressure
Mean (mm Hg) G SD 16.2 G 2.1 15.7 G 1.9 16.7 G 2.3 .08†
At or lower than target, n (%) 23 (43) 14 (50) 9 (36)
Medications
Mean (n) G SD 2.7 G 1.0 2.8 G 0.8 2.6 G 1.2 .70†
1 medication 7 (13) 2 (7) 5 (20)
2 medications 15 (28) 8 (29) 7 (28)
3 medications 19 (36) 13 (46) 6 (24)
O3 medications 12 (23) 5 (18) 7 (28)
ALT Z argon laser trabeculoplasty; AMD Z age-related macular degeneration; C:D Z cup-to-disc ratio; CDVA Z corrected distance visual acuity; IOP Z
intraocular pressure; LPI Z laser peripheral iridotomy; SLT Z selective laser trabeculoplasty
*Fisher exact test
†
Two-sample t test
canal after surgery but was otherwise stable; thus, no Corrected Distance Visual Acuity
intervention was performed. A steroid response Table 2 shows the CDVA at 1 year. One patient did
resulting in elevated IOP was identified at 5 weeks not have vision recorded at the final visit. Of the
in 1 eye and at 1 month in another eye. Both cases remaining 52 eyes, 47 (89%) had improved CDVA or
resolved once the steroids were discontinued. One maintained the preoperative CDVA. Of the 5 eyes
patient died from an unrelated systemic illness. with CDVA worsening at 1 year, 4 improved at
J CATARACT REFRACT SURG - VOL 38, NOVEMBER 2012

5. MULTIPLE TRABECULAR MICRO-BYPASS STENTS 1915
Figure 1. Overall mean IOP (mm Hg) and number of glaucoma med- Figure 2. Mean IOP (mm Hg) at each visit through 12 months strat-
ications from baseline through 12 months. Bars represent the stan- ified by number of stents. Bars represent the standard deviation
dard deviation (IOP Z intraocular pressure). (IOP Z intraocular pressure).
subsequent visits. The remaining 1 patient was lost to requiring fewer medications. However, no attempt to
follow-up. reduce the number of medications preoperatively
was made, potentially overestimating this effect.
DISCUSSION Compared with studies of implantation of a single
Samuelson et al.9 established that a single trabecular stent,8–11 use of multiple stents in this study resulted
bypass stent significantly reduced IOP and medication in a greater propensity to achieve a postoperative
burden at 1 year in patients having combined cataract– IOP of 15 mm Hg or less and a greater absolute reduc-
glaucoma implant procedures compared with patients tion in medications. This finding is consistent with the
having cataract surgery only. Studies by Fea8 and ex vivo work of Zhou and Smedley13 and Bahler
Spiegel et al.11 provide corroborating evidence of the et al.14 The use of multiple stents may exploit a greater
treatment effect of a single stent. range of circumferential flow and allow access to
In this open-label nonrandomized prospective se- a greater array of collector channels to establish phys-
ries, implantation of 2 or 3 trabecular bypass stents iologic flow of aqueous humor into the episcleral
in eyes having combined cataract surgery resulted in venous system.
significantly lower mean IOP at 1 year than preopera- Eyes in the 2-stent group had a significant reduction
tively (P!.001), with 77% of eyes achieving the post- in IOP and medications (P!.001 in all cases). Target
operative target pressure. This is despite no IOP was achieved in most cases (71%). Despite
preoperative medication washout period. The number a high mean preoperative medication burden in these
of glaucoma medications was also significantly moderate to advanced OAG patients, the majority
decreased from 2.7 medications preoperatively to 0.7 (79%) had a reduced preoperative medication burden
medications at 1 year (P!.001), with 83% of eyes at 1 year. The IOP and number of medications also sig-
nificantly decreased from preoperatively in the 3-stent
group (P!.001); the target IOP was achieved by 84%
compared with 43% preoperatively. There was a signif-
icant reduction in medications, with 88% of eyes
Table 2. Corrected distance visual acuity at 1 year.
Number (%)
CDVA Overall* 2-Stent Group* 3-Stent Group
20/40 or better 37 (64) 18 (64) 19 (76)
20/50–20/100 11 (21) 6 (21) 5 (20)
20/200 or worse 4 (8) 3 (11) 1 (4)
Figure 3. The mean number of glaucoma medications used in each CDVA Z corrected distance visual acuity
eye from baseline through month 12 stratified by number of stents. *Missing 1
Bars represent the standard deviation (*PZ.009; 4PZ.04).
J CATARACT REFRACT SURG - VOL 38, NOVEMBER 2012

6. 1916 MULTIPLE TRABECULAR MICRO-BYPASS STENTS
requiring fewer medications and 72% of eyes on no invasive surgeries, such as trabeculectomy and tube
medications at 1 year. These data show high rates of shunt placement, although this would have to be
IOP reduction and medication reduction with 2-stent evaluated in a future prospective study.
or 3-stent implantation and the potential to achieve The data reported by Samuelson et al.9 suggest that
target IOP levels after multiple stent implantation. a single stent implanted in combination with cataract
The significantly lower postoperative medication bur- surgery achieves postoperative target pressures that
den in the 3-stent than in the 2-stent group suggests are clinically meaningful for mild to moderate OAG
that stent titration is feasible. This allows the operating patients with comorbid cataracts. For more moderate
surgeon to determine the appropriate number of stents to advanced OAG patients with comorbid cataracts,
required to achieve the desired postoperative target this study found that 2 or 3 stents implanted in com-
IOP. Furthermore, if necessary, it may allow the option bined cataract procedures achieved mean IOPs that
of implanting additional micro-bypass devices in sub- were clinically meaningful for these patients. There-
sequent procedures to optimize the benefit-to-risk fore, single and multiple implants in combined cata-
ratio while preserving future management options. ract procedures may be preferable to the problems of
No major surgical problems or postoperative com- compliance (long-term morbidity and nonadherence)
plications were reported during the study. The most associated with chronic use of multiple medications
common complication of a blocked stent by the iris to control OAG. This may also improve patient conve-
was in most cases resolved by performing a laser iri- nience and quality of life.
dotomy that was well tolerated by the patient. In The clinical utility and demonstrated efficacy and
some instances, no intervention was required because safety of single and multiple stent implantation
the pressure was under control. The postoperative enables surgeons to select the implant therapy that is
hyphema resolved within the first month without most appropriate to achieve desired patient target
sequelae. Because of the nature of the insertion, mini- pressures. This approach appears to offer a high
mal reflux of blood is an anticipated normal physio- benefit-to-risk ratio for a given OAG disease stage
logic response immediately after stent implantation. severity and desired postoperative target IOP.
Despite a poor preoperative CDVA in approximately
one fourth of these eyes with advanced glaucoma,
the CDVA improved or was maintained in most eyes WHAT WAS KNOWN
and most patients achieved a postoperative CDVA of Implantation of 1 trabecular micro-bypass stent combined
20/40 or better. These postoperative findings are sim- with cataract surgery is safe and can more effectively
ilar to those reported by others.8–11,17 reduce IOP and topical ocular hypotensive medication
Further studies are needed to refine the relation- use compared with cataract surgery alone.
ship observed between the number of stents
implanted with concurrent cataract surgery and IOP
control. Determining the criteria for the number of WHAT THIS PAPER ADDS
stents to implant will also require further investiga- The implantation of 2 or 3 trabecular micro-bypass stents
tion. Although the outcomes in the 2-stent group combined with cataract surgery was performed safely
and 3-stent group were similar, we attempted to se- with a reduction in IOP and topical ocular hypotensive
lect more severe patients for implantation of 3 stents. medications.
However, our baseline analysis showed no signifi-
Implantation of multiple trabecular micro-bypass stents
cant difference between the 2 groups in any measure.
has the potential to further reduce IOP and topical ocular
Thus, a masked randomized trial is needed to better
hypotensive medications versus implantation of 1 trabec-
evaluate the relative efficacy of 2 versus 3 stents. Fur-
ular micro-bypass stent.
thermore, this series did not use a control group hav-
ing cataract surgery without stent implantation,
although previous studies8,9 established the benefit
of stent implantation and cataract surgery versus cat- REFERENCES
aract surgery only. The 6 cases of bilateral implanta- 1. Funnell CL, Clowes M, Anand N. Combined cataract and
tion could add additional bias; however, the cases glaucoma surgery with mitomycin C: phacoemulsification-
were spread evenly between the groups, minimizing trabeculectomy compared to phacoemulsification-deep
the overall impact. Despite its limitations, this study sclerectomy. Br J Ophthalmol 2005; 89:694–698. Available
contributes to the body of evidence showing the effi- at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1772685/pdf/
bjo08900694.pdf. Accessed July 17, 2012
cacy and safety of trabecular micro-bypass stent im- 2. Tsai H-Y, Liu CJ, Cheng C-Y. Combined trabeculectomy and
plantation and suggests that the implantation of cataract extraction versus trabeculectomy alone in primary
multiple stents may be an alternative to more angle-closure glaucoma. Br J Ophthalmol 2009; 93:943–948
J CATARACT REFRACT SURG - VOL 38, NOVEMBER 2012

7. MULTIPLE TRABECULAR MICRO-BYPASS STENTS 1917
3. Friedman DS, Jampel HD, Lubomski LH, Quigley H, Congdon N, 12. The AGIS Investigators. The Advanced Glaucoma Intervention
Levkovitch-Verbin H, Robinson KA, Bass EB. Surgical strate- Study (AGIS): 7. The relationship between control of intraocular
gies for coexisting glaucoma and cataract; an evidence-based pressure and visual field deterioration. Am J Ophthalmol 2000;
update. Ophthalmology 2002; 109:1902–1913 130:429–440
4. Hoffmann E, Schwenn O, Karallus M, Krummenauer F, Grehn F, 13. Zhou J, Smedley GT. A trabecular bypass flow hypothesis.
Pfeiffer N. Long-term results of cataract surgery combined with J Glaucoma 2005; 14:74–83
trabeculotomy. Graefes Arch Clin Exp Ophthalmol 2002; 14. Bahler CK, Smedley GT, Zhou J, Johnson DH. Trabecular
240:2–6 bypass stents decrease intraocular pressure in cultured
5. Hau S, Barton K. Corneal complications of glaucoma surgery. human anterior segments. Am J Ophthalmol 2004;
Curr Opin Ophthalmol 2009; 20:131–136. Available at: http:// 138:988–994
journals.lww.com/co-ophthalmology/fulltext/2009/03000/corneal_ 15. Chylack LT Jr, Wolfe JK, Singer DM, Leske MC,
complications_of_glaucoma_surgery.13.aspx. Accessed July Bullimore MA, Bailey IL, Friend J, McCarthy D, Wu S-Y; for
17, 2012 the Longitudinal Study of Cataract Study Group. The Lens
6. Minckler DS, Francis BA, Hodapp EA, Jampel HD, Lin SC, Opacities Classification System III. Arch Ophthalmol 1993;
Samples JR, Smith SD, Singh K. Aqueous shunts in glaucoma; 111:831–836. Available at: http://archopht.jamanetwork.
a report by the American Academy of Ophthalmology (Oph- com/data/Journals/OPHTH/18057/archopht_111_6_035.pdf.
thalmic Technology Assessment). Ophthalmology 2008; Accessed July 17, 2012
115:1089–1098. Available at: http://www.amo-romania.com/ 16. Canadian Ophthalmological Society evidence-based clinical
Document_Files/Ophthalmology%202008%20Jun.115(6)% practice guidelines for cataract surgery in the adult eye. Can
20p1089-98_AqueousShuntsinGlaucoma_vdcgv5.pdf. Ac- J Ophthalmol October 2008; 43(suppl 1):S7–S57. Available at:
cessed July 17, 2012 http://www.eyesite.ca/CJO/43S1/i08-133.pdf. Accessed July
7. Jampel HD, Musch DC, Gillespie BW, Lichter PR, Wright MM, 17, 2012
Guire KE; and the Collaborative Initial Glaucoma Treatment
17. Fernandez-Barrientos Y, Garcia-Feijoo J, Mart ınez-de-la-
Study Group. Perioperative complications of trabeculectomy
Casa JM, Pablo LE, Fernandez-Perez C, Garcia Sanchez J.
in the Collaborative Initial Glaucoma Treatment Study Fluorophotometric study of the effect of the Glaukos trabecular
(CIGTS). Am J Ophthalmol 2005; 140:16–22. Available at: microbypass stent on aqueous humor dynamics. Invest Ophthal-
http://new-glaucoma-treatments.com/wp-content/imagesfiles/ mol Vis Sci 2010; 51:3327–3332. Available at: http://www.iovs.
Perioperative%20Complications%20of%20Trab%20CIGTS. org/content/51/7/3327.full.pdf. Accessed July 17, 2012
pdf. Accessed July 17, 2012
8. Fea AM. Phacoemulsification versus phacoemulsification with OTHER CITED MATERIAL
micro-bypass stent implantation in primary open-angle glau- A. Spiegel D, Garcia-Feijoo J, Martinez de la Casa JM, Garcia-
coma: randomized double-masked clinical trial. J Cataract Sanchez J, GC-002 Study Group. iStent trabecular micro-
Refract Surg 2010; 36:407–412 bypass and concurrent cataract surgery: 24 month results.
9. Samuelson TW, Katz LJ, Wells JM, Duh Y-J, Giamporcaro JE; IOVS 2009; 50:E-Abstract 455. Abstract available at: http://
for the US iStent Study Group. Randomized evaluation of the tra- abstracts.iovs.org/cgi/content/abstract/50/5/455. Accessed
becular micro-bypass stent with phacoemulsification in patients July 17, 2012
with glaucoma and cataract. Ophthalmology 2011; 118:459–467
10. Spiegel D, Garc ıa-S
ıa-Feijoo J, Garc anchez J, Lamielle H.
Coexistent primary open-angle glaucoma and cataract: prelimi-
First author:
nary analysis of treatment by cataract surgery and the iStent
Graham W. Belovay, MD
trabecular micro-bypass stent. Adv Ther 2008; 25:453–464
€ €
11. Spiegel D, Wetzel W, Neuhann T, Sturmer J, Hoh H, Garc ıa- University of Toronto, Toronto,
Feijoo J, Mart ıa-S
ınez-de-la-Casa JM, Garc anchez J. Coexis- Ontario, Canada
tent primary open-angle glaucoma and cataract: Interim analysis
of a trabecular micro-bypass stent and concurrent cataract
surgery. Eur J Ophthalmol 2009; 19:393–399
J CATARACT REFRACT SURG - VOL 38, NOVEMBER 2012