EL-MINIA MED., BULL., VOL. 18, NO. 1, JAN., 2007
Mohamed
_____________________________________________________________________
IS IT WORTH TO CONVERT TO MICROINCISION
PHACOEMULSIFICATION?
By
Yasser Helmy Mohamed
Department of Ophthalmology, El-Minia Faculty of Medicine
ABSTRACT:
Purpose: To compare clinical outcomes of biaxial microincision and coaxial smallincision clear cornea cataract surgery.
Patients and Methods: Forty eyes (20 patients) were randomly operated through
clear corneal incisions using 2 techniques: Microincision cataract surgery was
performed through 1.5, 1.5 mm clear corneal incisions (CCIs) using bimanual
sleeveless phacoemulsification (cool phaco) in 1 eye and usual coaxial phaco was
performed on the other eye through a 3.0 mm CCI. Visual outcomes, astigmatic
changes, corneal thickness, and anterior chamber flare and cells preoperatively and at
1 day, 2 weeks, and 4 weeks were evaluated and analysed.
Results: All patients in the study underwent uneventful surgery. There were no
relevant clinical differences or intraoperative complications in either group. There
were no significant differences between the techniques regarding the postoperative
iritis, pachymetric measures, astigmatic changes, or visual outcome. There was
statistically significant difference between preoperative and postoperative visual
acuity in both groups (P value= 0.001) along the follow up period. No statistically
significant difference was found between the MICS and coaxial groups regarding the
BCVA all over the postoperative follow up period. Astigmatic change ranged between
0.25 D and 1.25 D with a mean of 0.75D in both groups.
Conclusion: Both techniques were safe and effective for cataract surgery. Bimanual
sleeveless phacoemulsification is similar to a standard phacoemulsification and
allowed excellent visual results in this series of patients.
KEY WORDS:
Bimanualphacoemulsification
Microincision-phaco
Pachymetry.
Coaxial phacoemulsification
Cold phaco
astigmatism (SIA), and reduce
incidence of postoperative inflammation.1
INTRODUCTION:
Cataract surgery techniques
have improved tremendously in recent
decades, starting with the introduction
of phacoemulsification in the late
1960s and the development of foldable
intraocular lenses (IOLs) in the late
1980s. These and more recent
innovations have led to surgery being
performed
through
increasingly
smaller self sealing incisions, resulting
in improved prognosis for visual acuity
(VA), less risk of surgically induced
One
technique,
biaxial
microincision clear cornea phacoemulsification, was first described by
Shearing et al., in 1985 and is
becoming increasingly popular among
cataract surgeons. This procedure uses
a separate irrigation instrument and a
sleeveless phaco tip to remove the
cataractous lens. Irrigation during
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Mohamed
_____________________________________________________________________
phaco is provided through an irrigating
chopper instead of the traditional
phaco hand-piece.
As a result, one instrument provides
irrigation to the anterior chamber while
the other instrument emulsifies and
then aspirates the nucleus. Because
irrigation is no longer provided
through the phaco sleeve, a bare needle
can be used to emulsify nuclear
fragments.2
difference is not the size of the
incision; it is the separation of inflow
and outflow. In recent years, through
several publications in the Journal of
Cataract & Refractive Surgery, several
specialists have attempted to document
and
quantify
the
effect
of
developments in techniques and
technology of phacoemulsification.2-7
Bimanual
microincision
phacoemulsification
has
multiple
advantages that make it a preferred
technique even in the absence of
microincision IOLs. The growing trend
in
bimanualmicroincision
phacoemulsification has prompted
many surgeons to evaluate this new
surgical technique.8
This technique allows a corneal
incision smaller than 1.5 mm but
requires pulsed phaco energy, which
prevents the development of high
temperatures in the cornea and
therefore reduces the incidence of
corneal burns. Because the biaxial
technique involves an incision smaller
than that of coaxial technique, one
might expect improved outcomes for
biaxial microincision versus coaxial
phacoemulsification.3
Some believe the technique will
become the standard of care in the near
future. Others do not, but they all share
their advice for performing it safely
and
effectively.
Microincision cataract surgery
provides advantages of wound
stability, improved control and reduced
chamber turbulence, resulting in early
visual rehabilitation and improved
results. Current techniques rely
predominantly on ultrasound based
phacoemulsification, which relies
heavily on expensive equipment and
consumables, restricting universal
application
of
this
technique
particularly in resource-limited settings
such as developing countries.4
AIM OF THE STUDY:
To compare clinical outcomes
of microincision bimanual phacoemulsification and coaxial clear cornea
phacoemulsification.
PATIENTS AND METHODS:
Forty eyes of twenty patients
with senile cataracts were randomly
operated through clear corneal
incisions
using
2
techniques:
Microincision cataract surgery (MICS)
was performed through two 1.5 mm
clear corneal incisions (CCIs) using
bimanual sleeveless phacoemulsification (cool phaco) in one eye and
usual coaxial phaco was performed on
the other eye through a 3.0 mm CCI.
Lens extraction performed
through
two
paracentesis-type
incisions offers unique advantages that
enhance surgical control and safety in
cataract and refractive lens surgery.
Understanding the essential features of
this lens extraction technique allows an
appreciation of its benefits. Reduction
of incision size represents only one of
many potential advantages that make
this a superior approach. The crucial
Patients with corneal disorders,
contact lens wear, previous intraocular
surgery, and a history of ocular trauma
or pathology were excluded from the
study. Eyes with more than 3 diopters
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Mohamed
_____________________________________________________________________
(D) of astigmatism were excluded from
the study, as astigmatic incisions
would be necessary.
one week, 2weeks,
postoperatively.
and
4weeks
All patients were subjected to full
ophthalmological examination both
preoperatively and postoperatively at
regular visits. Full ophthalmological
examination includes:
- Best corrected visual
acuity.
- Slit lamp examination.
- Applanation tonometry.
- Fundus examination.
- Refraction of patients
with great care of
astigmatic error before
and
4weeks
after
operation.
- Central
corneal
pachymetry
both
preoperatively and after
4weeks postoperatively
using
Compuscan
UPC1000 Storz.
Current technique for bimanual
microincision phaco may be reviewed
briefly as follow: two single1.5 mm
incisions are made with a disposable
knife about 90 degrees apart in the
clear cornea. Aqueous is exchanged for
a dispersive viscoelastic and a
continuous curvilinear capsulorhexis is
constructed with an insulin needle.
Following
hydrodissection
and
hydrodelineation, the nucleus is
impaled, chopped and mobilized using
20-gauge irrigating chopper and a 30degree beveled straight phaco needle
(Figure1). Epinucleus management
permits simultaneous extraction of
cortex in the great majority of cases
(Figure2). The capsule and anterior
chamber are filled with a cohesive
viscoelastic and separate limbal
incisions are performed for IOL
implantation in the bag. The residual
viscoelastic is irrigated
Evaluation of postoperative iritis in
the two groups by careful detection of
anterior chamber flare and cells was
encountered
during
slit
lamp
examination. Changes in astigmatic
error of all patients in the two groups
were calculated and evaluated. Both
intraoperative
and
postoperative
complications in the two groups were
encountered. Changes in the corneal
thicknesses in all patients of both
groups were calculated and evaluated.
In all cases, an AcrySof IOL
was inserted. In the microincision
group IOL was implanted through a
separate 3.0 mm clear corneal incision
at the 12-o' clock position. No stitches
were used in any of the cases in either
group.
All
patients
received
postoperative topical antibiotic and
corticosteroid treatment. Patients were
examined preoperatively and one day,
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Mohamed
_____________________________________________________________________
Figure (1): Showing shopping technique in bimanual phacoemulsification.
Figure (2): Showing process of cortex aspiration in bimanual
phacoemulsification.
cataract with age ranged between 5570 years old.
Postoperative
examination
showed no major postoperative
complications.
No
postoperative
detection of anterior chamber flare and
cells in all patients of the two groups
along the follow up period.
RESULTS:
All patients (twenty patients,
forty eyes) were subjected to
uncomplicated surgical procedures by
the same surgeon using the same
machine with insertion of a foldable
acrysof intraocular lens. All patients
(13 females, 7 males) had senile
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Mohamed
_____________________________________________________________________
There
was
statistically
significant
difference
between
preoperative and postoperative visual
acuity in both groups (P value= 0.001)
along the follow up period. No
statistically significant difference was
found between the MICS and coaxial
groups regarding the BCVA all over
the postoperative follow up period. In
both groups, the BCVA was ranged
between 6/60 and 6/12 with a mean of
6/18 preoperatively (P value= 0.93).
The mean postoperative BCVA in both
groups
was
6/6
one
month
postoperatively (P value= 0.974).
error in patients of the two groups (P
value= 0.63) after one month of follow
up. Astigmatic change ranged between
0.25 D and 1.25 D with a mean of
0.75D in both groups. Astigmatic
change between 0.25 and 0.5D was
present in 10% (2 eyes) in both groups.
Astigmatic change between 0.5 and
0.75 was present in 70% (14 eyes) in
the coaxial group and in 75% (15 eyes)
in group of MICS. Astigmatic change
between 0.75 and 1.0 D was present in
15% (3 eyes) in the coaxial group and
10% (2 eyes) in the group of MICS.
Astigmatic change between 1.0 and
1.25D was found in 5% (one eye) in
both groups (Figure 3). In both groups,
none of eyes showed astigmatic change
below 0.25 D or above 1.25 D.
There was no statistically
significant difference as regards to the
postoperative change in the astigmatic
Coaxial group
15%
5%
Biaxial group
10%
70%
10%
5%
10%
1- Between0.25 and0.5D
1- Between0.25 and0.5D
2- Between0.50 and0.75D
2- Between0.50 and0.75D
3- Between0.75 and 1.0D
3- Between0.75 and 1.0D
4- Between1.0and1.25D
75%
4- Between1.0and1.25D
Figure (3): Pie chart showing the degree of postoperative
astigmatic change in both groups.
There was no statistically
significant value between the two
groups as regards to the pachymetric
measures
after
one
month
postoperatively(P
value=
0.785).
Central corneal thickness ranged
between 512 and 532u preoperatively
with a mean of 524u and ranged
between 525 and 548u postoperatively
with a mean of 538u in the coaxial
group. Central corneal thickness
ranged between 519 and 535u
preoperatively with a mean of 526u
and ranged between 530 and 551u
postoperatively with a mean of 541u in
the MICS group (Figure 4).
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Pachymetric changes in both groups
545
540
Preop-Coaxial gp
Postop-Coaxial gp
Preop-Biaxial gp
Postop-Biaxial gp
535
530
525
520
515
1
Figure (4): Column chart showing pachymetric changes in both groups.
DISCUSSION:
The main evolution that
cataract surgery experienced during the
last decades has been parallel to the
decrease in the incision size. When
small incision phacoemulsification
with foldable IOL implantation became
the standard technique for cataract
removal, most of the presumed
advantages that were anticipated by
pioneers such as Charles Kelman were
confirmed. A shorter recovery time,
less surgically induced astigmatism,
and improved surgical outcomes were
observed. Because the concept of
reducing incision size was clearly
related to better surgical outcomes,
modification of the surgical technique
was necessary to achieve this goal9
All over the world surgical
incisions are becoming smaller and
smaller and more so in ophthalmology.
The advent of bimanual phaco has
made cataract surgery now possible
through a sub 2 mm incision. With
bimanual microincisional phacoemulsification, we are able to achieve nearly
watertight conditions and an almost
completely closed system. We are
using smaller incisions, which are
inherently safer, and we have improved
followability because the fluid enters
the eye from one side and leaves
through the other. This flow avoids
creating competing currents around the
phaco tip, such as in coaxial
phacoemulsification. In addition, the
incoming irrigation flow can be used as
a tissue manipulator, which aids in
directing tissue to the phaco tip.7
Concurrent improvement in
ultrasound technology and instrumentation, including new IOL technology,
accompanied the evolution of new
surgical techniques, resulting in less
tissue trauma, less SIA, and faster
recovery.9
Alio et al.,9 have used the term
microincision cataract surgery to
describe the procedure of cataract
surgery with IOL implantation through
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Mohamed
_____________________________________________________________________
such 2mm microincisions. Fluidics
optimization in MICS aims for an
improved control in pressure and value
changes during cataract surgery, which
requires a closed and stable anterior
chamber. Using a closed compartment
leads to a reduction of fluid circulation
in the anterior chamber.
However, it is really a superior method
that facilitates cataract surgery in
general. Its benefits are not just about
incision size, but it will have added
value once microincision IOLs become
available. A variety of names have
been used to refer to this procedure.
Based on its defining features,
SIMPLE, an acronym for Separate
Infusion Microincision Phacoemulsification Lens Extraction, seems to be a
good alternative.10
Investigators
are
eagerly
comparing ways to perform phacoemulsification to obtain the best results for
patients.
Bimanual
microincision
phaco has been receiving a great deal
of attention and is being compared
with conventional phaco. The growing
trend in bimanual microincision
phacoemulsification has prompted
many surgeons to evaluate this new
surgical technique. Some believe the
technique will become the standard of
care in the near future. Others do not,
but they all share their advice for
performing it safely and effectively.
A recent study by Kurz et al.,11
compared the outcomes of bimanual
microincision phacoemulsification to
coaxial microincision phacoemulsification. This prospective randomized
study of 70 eyes in 70 patients
evaluated the intraoperative parameters
of mean phacoemulsification time,
total phacoemulsification percentage,
effective phacoemulsification time,
total balanced salt solution (BSS)
utilized, total surgical time, and final
wound incision size. In addition, the
postoperative parameters of corneal
thickness, endothelial cell count,
anterior chamber inflammation, visual
acuity, and induced astigmatism by
vector analysis were also evaluated.
Bimanual microincision phacoemulsification has multiple advantages
that make it a preferred technique even
in the absence of microincision IOLs.
The first point concerns the fluidics.
During coaxial phacoemulsification, a
portion of the irrigation fluid is
captured by irrigation immediately
after it flows out of the sleeve. Having
the irrigation so close to the aspiration
means that, the nuclear fragments can
be pushed away. So having the
irrigation in one end and the aspiration
in another end means that there is an
increase in followability.2
Both techniques were found to
be safe and effective, with the only
statistically significant differences
demonstrated being less total volume
of BSS utilized and a lower total
surgical time in the bimanual
microincision group.
An earlier study by Alio et al.,9
comparing bimanual to coaxial microincision phacoemulsification demonstrated lower mean total phacoemulsification percentage, lower mean
effective phaco time, and less
surgically induced astigmatism with
the bimanual technique. There was no
difference in the total amount of BSS
utilized.
The second consideration,
having
separate
irrigation
and
aspiration, allows surgeons to use the
irrigating fluid like a surgical tool.2
There are critics who say there
is no role for bimanual microincision
phaco because of the need to enlarge
the incision for IOL insertion.
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These studies demonstrate the
possible advantages of a bimanual
technique over a coaxial approach in
regards to both intraoperative and
postoperative parameters. The lack of
consistent findings between studies
reveals the difficulty of drawing
consistent conclusions regarding these
parameters.
endothelium and there was no
statistically different values between
the two groups after one month
postoperatively as regards pachymetric
measures.12
Wilczynski M et al.,13 compared
the two groups as regards BCVA and
endothelial count loss and concluded
that there was no significant difference
between BCVA in the two groups
postoperatively. Also, Patients in the
MICS group lost an average of 9.5% of
corneal endothelial cells, whereas
patients
after
standard
phacoemulsification lost about 7.6% of cells.
This
difference
was
statistically
insignificant.
Alio et al.,9 concluded that,
reduction of SIA is the most significant
and important achievement of MICS in
their study. A great advantage of MICS
surgery is that the microincisions do
not produce an increase in astigmatism,
and this is considered important
because cataract surgery today is
considered more and more a refractive
procedure.
Larger studies with more
participants should be carried out to
study further the biochemical changes
induced at the level of the cornea,
possibility of corneal burns, amount of
leakage, and amout of astigmatism
induced by the surgery.
Alio et al.,9 used foldable IOL
inserted through 1.5mm corneal
incision in the group of MICS. In this
study, there was no difference in both
groups as regards to SIA. This is may
be due to the use of usual foldable
lenses in both groups with the same
size and site of corneal incision for
implantation of IOL.
Microincision surgery has
become the Holy Grail among cataract
surgeons in recent years. In fact, it’s
been the impetus behind the mounting
interest in microincision phacoemulsification. Yet, most ophthalmologists
are far from having all the pieces of the
puzzle in place to perform true micro
phaco and for the majority of
physicians to adopt it as their technique
of choice.5 Opponents of bimanual
microincision surgery cite the need for
a new learning curve, investment in
additional instrumentation, and increased cataract surgical costs. Proponents
cite improved “followa-bility,” easier
cortex removal, and safer surgery in
difficult cases where 2 similarly sized
incisions give options for approaching
the lens from 2 different directions.14
Alio et al.,9 and Kurz et al.,11
concluded from their studies that, there
were no statistically different values
between the two groups as regards to
BCVA, mean flare value, and mean
pachymetric measures. These results
are consistent with results in this study.
Kurz et al.,11 and Alio et al.,9
used specular microscope to evaluate
the difference between the two groups
as regards to endothelial cell count
loss. They concluded that there was no
statistically difference between the two
groups regarding the mean percentage
of endothelial cell loss. In this study,
secular microscopy was not available
to make this comparison. In this study,
indication of the state of the corneal
Most physicians are sitting on
the sidelines, refusing to test the new
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technique for a number of reasons.
Micro phaco is difficult to learn for the
average cataract surgeon, for it requires
two hands instead of one. The learning
curve increases the risk for postoperative complications. There’s no
U.S. Food and Drug Administrationapproved intraocular lens designed to
fit through a 1.2- to 1.5-mm incision
and there may not be for several years.
Presently, cataract surgeons performing micro phaco have to enlarge
these microincisions anyway to fit the
current lenses inside the eye. If you’re
not performing micro phaco on your
patients currently, don’t feel guilty or
pressured to do so, because true micro
phaco is still not ready for prime time.
nologies. J Cataract Refract Surg 2002;
28: 1054-1060.
6- Hoffman RS, Fine IH, Packer M,
Brown LK.: "Comparison of sonic and
ultrasonic phacoemulsification utilizing
the Staar Sonic Wave phacoemulsification system." J Cataract Refract
Surg 2002; 28:1581-1584.
7- Fine IH, Packer M, Hoffman
RS.: “Power Modulations in New
Technology: Improved Outcomes.” J
Cataract Refract Surg 2004; 30:10141019.
8- Archinoff SA.: Biaxial phacoemulsification [letter]. J Cataract Refract
Surg 2005; 31:646.
9- Alio J, Rodriguez-Prats JL, Galal
A,
Ramzy
M.:
Outcomes
of
microincision cataract surgery versus
coaxial phacoemulsification. Ophthalmology 2005;112:1997–2003
10- Osher RH, Barros MG, Marques
DM, Marques FF, Osher JM.: Early
uncorrected visual acuity as a
measurement of the visual outcomes of
contemporary cataract surgery. J
Cataract Refract Surg. 2004;30:1917-20.
11- Kurz S, Krummenauer F, Gabriel
P, Pfeiffer N, Dick HB.: Biaxial
microincision versus coaxial smallincision clear cornea cataract surgery.
Ophthalmology. 2006 Oct; 113(10):
1818-26.
12- Lundberg B, Jonsson M, Behndig
A. Postoperative corneal swelling
correlates strongly to corneal endothelial
cell loss after phacoemulsi-fication
cataract surgery. Am J Ophthalmol.
2005 Jun;139(6):1035-41.
13- Wilczynski M, Drobniewski I,
Synder A, Omulecki W.: Evaluation of
early corneal endothelial cell loss in
bimanual microincision cataract surgery
(MICS) in comparison with standard
phacoemulsification. Eur J Ophthalmol.
2006 Nov-Dec; 16 (6):798-803.
14- Mamalis N. Is smaller better? J
Cataract Refract Surg 2003; 29:1049-50.
Hopefully, further comparative
studies of these 2 techniques will
provide useful information to help
surgeons determine if making a transition to a bimanual technique is
worthwhile.
REFERENCES:
1- Dick
HB,
Schwenn
O,
Krummenauer F, et al.,: Inflammation
after sclerocorneal versus clear corneal
tunnel phacoemulsification. Ophthalmology 2000; 107:241-7.
2- Fine IH, Hoffmann RS, Packer
M.: Optimizing refractive lens exchange
with
bimanual
microincision
phacoemulsification. J cataract Refract
Surg 2004; 30:550-4.
3- Olson RJ.: Clinical experience
with 21-gauge manual microphacoemulsification using Sovereign WhiteStar
technology in eyes with dense cataract. J
Cataract Refract Surg. 2004;30:168-72.
4- Donnenfeld ED, Olson RJ,
Solomon R, Finger PT, Biser SA, Perry
HD, Doshi S.: Efficacy and woundtemperature gradient of whitestar. J
Cataract
Refract
Surg.
2003
Jun;29(6):1097-100.
5- Fine IH, Packer M, Hoffman
RS.: New Phacoemulsification Tech-
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‫هل من االجدر التحول الى الشق المجهرى الستحالب العدسه؟‬
‫ياسر حلمى محمد‬
‫قسم الرمد – كلية طب المنيا‬
‫الغرض من البحث ‪ :‬هو قارنةوب نوال تاةجورالك تنيكاةاياول ناتاوب تاقاورا تانامورا نراق ور‬
‫تاص جال تحرداب تاقح ن ثةرالاب تاقح ن‪.‬‬
‫و‬
‫تاص جاب‬
‫طريقة البح ‪:‬جق تاتاب تاقارا تانامرا اعشنال قنامر (تننعال عاةر) نراق ر‬
‫قسجخدقال طنااجال‪.‬‬
‫تاطنااوب تن اوه هو ه ثةرالاوب تاقحو ن عول طناوا شوا تاانةاوب شوواال يو قة ور‪ 1¸ 5‬قو نرسووجخدت‬
‫تاص جال قةا ع تاغطرا (تااقاص) و تحود تاعاةوال تاعوال تنخون جقو‬
‫قسنرن تاق ر‬
‫تاتاب تاقاره تانامرا نراق ر تاص جال تحرداب تاقح ن عل طناا شا تاانةاب ‪ 3‬ق ‪.‬‬
‫قاق حككو ةجورالك تاق قو عجال قول ةرحاوب تاةجورالك تانصوناب تاجغاونت وه دن وب تنةحونت‬
‫(تنسج قرجا ) سقك تاانةال تاج رنر تاااحاب‪.‬‬
‫و د تاوب تخجا ور تيكاةاياول ت قمورعثر تثةورا تاعقكاور‬
‫نتائج البح ‪ :‬ةجك تانحث عل عد‬
‫اكق ق عجال‪.‬‬
‫ااس هةرك ن تحصرالال نال تاطنااجال قل حاث تناج رب تاااحه نعد تاعقكاب سقك تاانةاب‬
‫دن ر تنةحنت ت تاةجرالك تانصناب ‪.‬‬
‫اجوون تم قعوود تاجغاوون ووه دن ووب تنةحوونت قوورنال ‪ 1¸25: 0¸25‬داو نجن نقج سووط اعوورد ‪0¸ 75‬‬
‫دن ب ه يا تاق ق عجال‪.‬‬
‫خالصة البح ‪:‬جعجنن يوا تاطونااجال تقورل ت رعكاوب ناتاوب تاقاورا تانامورا نتحاور جيو ل‬
‫تاطنااووب ثةر الاووب تاقحو ن قسوور اب نحرداووب تاقحو ن ووه هو ه تاق ق عوول تانحثاوول قوول حاووث تاةجوورالك‬
‫تانصناب‪.‬‬
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