Download Combination Laser Cataract Surgery, Micro

CATARACT SURGERY
Combination Laser
Cataract Surgery,
Micro-Bypass Stent in
Glaucoma Patients
Two advanced technologies have set the stage for an innovative surgical approach that allows
patients to be less dependent on their glasses and perhaps their glaucoma medications as well.
BY JUSTIN SCHWEITZER, OD
G
LASER CATARACT SURGERY
The Food and Drug Administration cleared femtosecond laser systems for cataract surgery in 2010, and currently, they are used to create corneal incisions, capsulotomies, astigmatic relaxing incisions, and for fragmentation of the lens.3 Cataract surgeons are faced with high
expectations for refractive outcomes, and the goal is to
achieve results as close to the intended target as possible.
A well-centered and perfect capsulorhexis is more
important than ever in achieving an outcome of emmetropia. It is especially important because of the increasing use of accommodative and multifocal IOLs. These
premium IOLs are pupil dependent and can be affected
(Courtesy of John Berdahl, MD.)
laucoma affects more than 2 million people
in the United States, and it is believed that
number will increase to more than 3 million by
2020 due to the aging of the US population.1
Cataracts are the leading cause of low vision among
white, black, and Hispanic people, accounting for 50%
of bilateral visual acuity worse than 20/40.2 These two
conditions often coexist, as they both become more
common with age.1,2 In our center, at Vance Thompson
Vision, there is not a much more exciting procedure performed than laser cataract surgery, which we call refractive laser-assisted cataract surgery or ReLacs, in combination with the insertion of the iStent trabecular microbypass stent (Glaukos Corporation) for our patients with
cataracts and mild to moderate glaucoma.
Figure 1. Optical coherence tomography view during laser
cataract surgery that allows the cataract surgeon to plan the
location and depth of incisions.
by a decentered or imperfect capsulorhexis. Nagy et al
conducted a study to compare femtosecond lasercreated capsulorhexes with manually created capsulorhexes.4 The study results showed better IOL centration in the femtosecond laser group compared to the
manual capsulorhexis group, and it also showed that
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(Courtesy of John Berdahl, MD.)
CATARACT SURGERY
Administration-approved medical device known to be implanted in the human body.6 The
stent was designed to serve as a
bypass through the trabecular
meshwork to facilitate physiological outflow and, thus, lower
IOP.6 The iStent, on the tip of
an inserter, is placed in the eye
through the same clear corneal
incision used during cataract
surgery. It is then implanted
through the trabecular meshwork and into Schlemm canal
with the assistance of a gonioprism (Figure 2).
Figure 2. The iStent implanted through a clear corneal incision, through the trabecular
The implantation of the
meshwork into Schlemm canal with the assistance of a gonioprism.
iStent at the same time as cataract surgery has a better safety
there was a higher rate of IOL decentration when there
profile compared with traditional filtration surgeries
was an irregularity of the capsulorhexis’ shape.4
in combination with cataract surgery. Samuelson et
The performance of premium IOLs, and diffractive lens- al demonstrated that the device plus cataract surgery
es in particular, can also be affected by decreased contrast achieved no compromise in visual outcomes or safety
sensitivity. In glaucomatous eyes, studies have shown that of the cataract surgery procedure.6 Patients who underan increase in visual field loss correlates with a decrease
go traditional filtration surgeries are at risk for compliin contrast sensitivity.5 Patients with visual field loss, and
cations such as bleb leaks, bleb infections, or hypotony,
thus decreased contrast sensitivity, are not good candiwhich are not a concern for patients implanted with
dates for diffractive premium IOLs; they are better suited
the iStent.6-8
for a monofocal IOL or an accommodating IOL.
The ability to create accurate limbal relaxing incisions
COMBINED SURGERY
(LRIs) is another advantage of cataract laser systems.
The advanced technologies of laser cataract surgery
The machine can perform corneal or LRIs to correct up
and the iStent have set the stage for an innovative
to 3.50 D of astigmatism (but are commonly used to
surgical approach that allows patients to be less depencorrect up to 2.00 D) and minimize the inconsistencies
dent on their glasses after cataract surgery and targets
of depth, axis, arc length, and optical zone seen with
mild to moderate glaucoma all in one surgery.
manual LRIs (Figure 1).3
Cataract surgery alone has been shown to reduce IOP
Corneal endothelial damage, corneal edema, and ante- in patients with mild to moderate glaucoma.9-12 Poley
rior chamber inflammation are a concern with cataract
et al conducted a study of 588 eyes to evaluate the
surgery in patients with certain conditions such as Fuch
long-term effects of cataract extraction in normotendystrophy and glaucoma. Using the femtosecond laser,
sive and ocular hypertensive eyes. Patients who had the
surgeons can divide the lens nucleus with low-energy
highest presurgical IOPs obtained the greatest reducpulses without the need to enter the eye, reducing the
tions after cataract extraction at 1 year.9
energy needed in the phacoemulsification procedure.
Is it possible to lower the IOP to an even greater
Nagy et al reported day-1 postoperative data from nine
extent in patients with mild to moderate glaucoma and
patients showing mild corneal edema, trace cell and flare, coexisting cataracts without simply adding more mediand no eyes having an intraocular pressure (IOP) greater
cations? A few millimeters of mercury in IOP reduction
than 21 mm Hg at any time.4
can make all the difference in slowing down or stopping progressive glaucoma. The iStent in conjunction
TRABECULAR MICRO-BYPASS STENT
with cataract surgery has been shown to reduce IOP on
In 2012, the iStent was approved by the Food and
fewer medications versus cataract surgery alone.6,13
Drug Administration for use in conjunction with
Samuelson et al revealed a few key points about
cataract surgery. It is the smallest Food and Drug
cataract surgery plus iStent insertion versus cataract
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CATARACT SURGERY
“The first important finding in the
study was that a 20% reduction
in IOP without medication was
achieved in 66% of eyes treated
with cataract surgery plus an iStent
versus 48% of eyes treated with
cataract surgery alone.”
sugery alone. The first important finding in the study
was that a 20% reduction in IOP without medication
was achieved in 66% of eyes treated with cataract
surgery plus an iStent versus 48% of eyes treated with
cataract surgery alone.6 A second takeaway point from
this study is that twice as many patients in the cataract
surgery-only group went back on medications at 1 year
compared with patients in the cataract surgery-plusiStent group.6
Similar to the Samuelson study, Fea conducted a
study that showed the advantages of a combined procedure (cataract plus iStent) versus cataract surgery
alone. The combined group in the Fea study had an
additional 3 mm Hg of IOP reduction compared with
the cataract surgery-alone group.13 Throughout the
study, more patients who had the combined procedure remained medication free in comparison to the
cataract surgery-alone group. Fifteen months postoperatively, 67% of the combined group were medication
free compared with 24% of the cataract surgery-alone
group.13
Patients’ noncompliance with glaucoma medications
is an ongoing concern for eye care providers. The more
complex a glaucoma dosing regimen is, the more likely
a patient will be noncomplaint.14 Cataract surgery plus
iStent implantation has shown it is possible to decrease
how many glaucoma medications a patient is on, thus
making their compliance more likely.6,13,14
Significant IOP reduction in combination with cataract surgery is possible, and yet another advantage of
the iStent in combination with laser cataract surgery is
that the refractive predictability is similar to cataract
surgery alone. The pairing of laser cataract surgery and
the device allows for an accurate refractive outcome in
combination with a powerful glaucoma surgery. This
is not the case with a majority of other combination
cataract and glaucoma surgeries involving filtration.
Trabeculectomy has been shown to induce corneal
curvature changes, adversely affecting postoperative
visual acuity.15,16 Due to these corneal changes, it is difficult to predict the refractive outcome with the combination of trabeculectomy and cataract surgery.
CONCLUSION
As the incidence of glaucoma and cataract increase
with the advancing age of the US population, patients
will continue to explore and seek out new options to
achieve better refractive outcomes and reduce the use
of medications. In our center, we have patients with
mild to moderate glaucoma who are seeking a solution that decreases their dependence on glasses and
glaucoma medication usage. We now have a technology in laser cataract surgery, what we call ReLacs, to
remove their cataracts, which will help lower their IOP
and make them less dependent on spectacles. In conjunction with laser cataract surgery, the insertion of
an iStent will allow for further IOP reduction, possibly
reducing the burden of their medication usage. These
types of patients are some of the happiest that come
through our clinic on a daily basis. n
Justin Schweitzer, OD, is in practice at Vance
Thompson Vision in Sioux Falls, South Dakota.
He acknowledged no financial interest in the
product or company mentioned herein.
Dr. Schweitzer may be reached at
[email protected].
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United States. Arch Ophthalmol. 2004;122(4):532-538.
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