ARTICLE
Comparison of the effect of AquaLase
and NeoSoniX phacoemulsification
on the corneal endothelium
Nada Jirásková, MD, PhD, Jana Kadlecová, MD, Pavel Rozsı́val, MD, PhD,
Jana Nekolová, MD, Jana Pozlerova, MD, Zlatica Dúbravská, MD
PURPOSE: To compare the extent of corneal endothelial cell loss and pachymetry changes in 2
age-based groups of patients who had cataract removal by AquaLase (Alcon) phacoemulsification
in 1 eye and NeoSoniX (Alcon) phacoemulsification in the contralateral eye.
SETTING: Department of Ophthalmology, University Hospital, Hradec Králové, Czech Republic.
METHODS: This prospective clinical study comprised 28 patients younger than 80 years (Group A)
and 28 patients 80 years or older (Group B) with bilateral cataract having lens removal using AquaLase in the right eye and NeoSoniX in the left eye. The nuclei were graded clinically on the basis of
hardness. The endothelial cell count (ECC), pachymetry, and best corrected visual acuity (BCVA)
were evaluated preoperatively and postoperatively. The mean ECC and pachymetry values
(GSD) were calculated in each group, with differences between right and left eyes analyzed using
the paired t test.
RESULTS: In Group A, the differences in the postoperative changes in ECC and pachymetry between
AquaLase and NeoSoniX were not statistically significant. In Group B, there were statistically
significant differences in postoperative changes in ECC and pachymetry, with the results better
in the AquaLase eyes. The BCVA immediately after surgery was better than preoperatively in all eyes.
CONCLUSION: The results suggest that AquaLase cataract extraction is safe for the endothelium,
even in older patients with harder cataracts and a lower ECC count preoperatively.
J Cataract Refract Surg 2008; 34:377–382 Q 2008 ASCRS and ESCRS
Phacoemulsification is now the preferred technique
for cataract removal.1–4 Continuous improvement in
technology and technique have made cataract surgery
safer and more efficient.5–7 The quest for lens extraction with reduced intraocular energy resulted in
power modulations and supplemental energy sources,
which have improved outcomes.8–10
Conventional ultrasound (US) phacoemulsification
is created in a handpiece when power is applied to piezoelectric crystals that convert the electrical energy
into mechanical vibrations of the phaco needle. The
phaco needle tip is used to emulsify the lens material
at US frequencies generally between 25 KHz and
62 KHz, which creates thermal and cavitational energy
that has the potential to damage the cornea. The NeoSoniX handpiece (Alcon) delivers oscillatory sonic and
axial US energy separately or in combination. The phaco tip has a variable rotational oscillation up to 2 degrees at an approximate frequency of 100 Hz. This
lower frequency does not produce significant thermal
Q 2008 ASCRS and ESCRS
Published by Elsevier Inc.
energy and thus minimizes the risk for thermal injury.
Previous studies11 suggest that US coupled with
oscillatory motion is more efficient than axial energy
alone.
The AquaLase liquefaction device (Alcon), one of
the more recent phacoemulsification technologies,
uses warm pulses (57 C) of balanced salt solution
(BSS) to strain and dissolve the lens for aspiration.
Within the AquaLase handpiece, 4 mL fluid pulses
are generated as current passes between electrodes.
These pulses then travel from the handpiece into the
tip of the instrument and eventually into the eye.
The fluid pulses pass through a channel in the outer
sleeve of the tip and exit through a single small opening located in the lumen of the polymer application tip
near its distal end. Aspiration of the liquefied lens material occurs through the central lumen of the tip. The
BSS pulses are delivered at a maximum rate of 50 Hz,
and the magnitude of the pulses can be linearly controlled by depressing the footpedal.
0886-3350/08/$dsee front matter
doi:10.1016/j.jcrs.2007.10.033
377
378
EFFECT OF AQUALASE AND NEOSONIX ON CORNEAL ENDOTHELIUM
The purpose of this study was to evaluate the effect
of AquaLase and NeoSoniX technology on corneal
endothelial cells during phacoemulsification.
PATIENTS AND METHODS
This prospective clinical study included patients with bilateral lens opacification scheduled for cataract surgery at the
Department of Ophthalmology, University Hospital, Hradec
Králové. Patients were selected from the department queue.
For patients to be eligible for the study, both eyes had to have
cataract, preferably with similar density grades. Patients
with ocular surface disease, endothelial or stromal corneal
dystrophy, or corneal scars were excluded. The study purpose, procedures, and responsibilities were explained to all
potential participants, and informed consent was obtained
from all selected patients.
Patients were divided into 2 groups based on age. Group
A comprised patients younger than 80 years and Group B,
patients 80 years or older.
Before surgery, a complete eye examination was performed. The examination included distance best corrected
visual acuity (BCVA) using Snellen optotypes, endothelial
cell density (ECD), and pachymetry using a specular microscope (Noncon Robo Pachy SP-9000, Konan Medical). Cataracts were graded clinically on the basis of hardness
according to the Buratto classification2 (1 to 5 scale). Patients
with a very hard nucleus (grade 5 to brown or black rock
hard cataracts) were not included in the study.
Surgery was performed by 1 of 2 surgeons (N.J., P.R.);
both eyes of each patient were operated on by the same surgeon. Phacoemulsification was performed using topical anesthesia, a 3.0 mm limbal incision, and AquaLase in the
right eye and NeoSoniX in the left eye. The standard soft
polymer needle (flared at the tip) with a 1.10 mm inner diameter and 1.32 mm outer diameter was used in all AquaLase
cases and a 30-degree round 1.10 mm flared ABS tip, in all
NeoSoniX cases. The phaco settings were modified for each
cataract grade with both lens removal modalities (Tables 1A
and 1B). Sodium hyaluronate 3%–chondroitin sulfate 4%
with sodium hyaluronate 1% (DuoVisc) was used as an
ophthalmic viscosurgical device (OVD) in all eyes. The dispersive OVD (sodium hyaluronate 3.0%–chondroitin sulfate
4.0% [Viscoat]) was used during creation of the capsulorhexis and the cohesive OVD (sodium hyaluronate 1.0%
Accepted for publication October 23, 2007.
From the Department of Ophthalmology, University Hospital,
Hradec Králové, Czech Republic.
No author has a financial or proprietary interest in any material or
method mentioned.
Presented in part at the ASCRS Symposium on Cataract, IOL and
Refractive Surgery, San Diego, California, USA, April 2007.
Supported in part by research project MZO 00179906 from the
Ministry of Health, Prague, Czech Republic, and in part by a grant
from Alcon, Fort Worth, Texas, USA.
Corresponding author: Nada Jirásková, MD, PhD, Department of
Ophthalmology, University Hospital, Sokolska 581, 500 05 Hradec
Králové, Czech Republic. E-mail: jirasnad@fnhk.cz.
[Provisc]), for intraocular lens (IOL) insertion. In all eyes,
a single-piece IOL (AcrySof, Alcon) was implanted in the
bag using the Monarch II injector system. Postoperatively,
all patients received topical tobramycin 3.0 mg/mL–dexamethasone 1.0 mg/mL (TobraDex) 5 times daily for 2 weeks
followed by dexamethasone 1.0 mg/mL 3 times daily for 2
weeks.
Patients were examined 1 day, 1 week, and 1, 3, and 6
months after surgery. At each visit, refraction was performed
and BCVA was measured using Snellen optotypes. The ECD
and pachymetry were evaluated 1 week and 1, 3, and 6
months after surgery. The mean pachymetry and ECD
values were calculated.
Statistical analysis of the postoperative changes in pachymetry and endothelial cell count (ECC) between right eyes
and left eyes in both groups was performed using the paired
t test. All mean values are reported with their standard
deviation.
RESULTS
The 56 patients were divided into 2 groups. The mean
age in Group A (n = 28) (younger than 80 years) was
63 years (range 50 to 65 years). The mean age in Group
B (n = 28) (80 years or older) was 83 years (range 80 to
93 years). Group B had a higher frequency of harder
nuclei (Figure 1). No eye having NeoSoniX phacoemulsification had a cataract of grade 4.
Phacoemulsification Parameters
AquaLase Table 2A shows the median phacoemulsification values for AquaLase according to nuclear
grade. The median AquaLase time was 0.3 seconds
(range 0 to 4.3 seconds) in Group A and 0.9 seconds
(range 0.1 to 3.8 seconds) in Group B. The number of
pulses ranged from 0 (soft lens; only irrigation/aspiration using high vacuum was used) to 5280 (hard cataract, grade 4). The median number of pulses was 493 in
Group A and 1410 in Group B.
Fixed flow and vacuum were used in all cases, with
a dynamic rise of 2 or 3 (Table 1A). The mean peak vacuum was 537 G 77 mm Hg (median 542 mm Hg; range
369 to 729 mm Hg) in Group A and 520 G 118 mm Hg
(median 570 mm Hg; range 60 to 596 mm Hg) in
Group B.
NeoSoniX Table 2B shows the median phacoemulsification values for NeoSoniX according to nuclear
grade. The median phaco power was 5.95% (range
0% to 16.5%) in Group A and 5.00% (range 2.0% to
21.0%) in Group B. The median effective phaco time
was 7.2 seconds (range 0 to 16.1 seconds) in Group A
and 7.0 seconds (range 1.3 to 22.6 seconds) in Group B.
Fixed flow and vacuum were used in all cases, with
a dynamic rise of 3 or 4 (Table 1B). The mean peak vacuum was 532 G 77 mm Hg (median 548 mm Hg; range
380 to 696 mm Hg) in Group A and 570 G 29 mm Hg
J CATARACT REFRACT SURG - VOL 34, MARCH 2008
379
EFFECT OF AQUALASE AND NEOSONIX ON CORNEAL ENDOTHELIUM
Table 1A. AquaLase settings by cataract grade.
Cataract Grade
1
2
3
4
Linear Magnitude
(% @ pps)
Burst (%)
60 @ 40
80 @ 50
100 @ 50
100 @ 50
50
50
50
70
Fluidics (cm), Fixed Flow (cc/min),
Fixed Vacuum (mm Hg)
96, 36, 500
100, 40, 550
105, 40, 600
105, 40, 650C
Dynamic Rise
2
2
3
3
pps Z pulses per second
(median 553 mm Hg; range 545 to 625 mm Hg) in
Group B.
Surgical Outcomes
Figure 2 shows the mean ECC values and Figure 3
shows the mean pachymetry values in Group A and
Group B preoperatively as well as 1 week and 1, 3,
and 6 months postoperatively. In Group A, the differences in postoperative changes in ECC and pachymetry between the right eye (AquaLase) and left eye
(NeoSoniX) were not statistically significant. In Group
B, there were statistically significant differences in
postoperative changes in ECC and pachymetry, with
the results better in AquaLase eyes. Figure 4 shows
the P value for ECC (A) and pachymetry (B) in both
groups at each postoperative visit.
The BCVA improved in all eyes immediately after
surgery and remained stable during the entire follow-up (Figure 5). In Group B, 16 patients (57%) had
incipient age-related macular degeneration, which
was the cause of the worse results in this group.
DISCUSSION
The art and science of cataract removal by Kelman US
phacoemulsification12,13 are continually evolving. Improvements in technique and technology have made
the procedure safer and more efficient than in the
past. Each surgeon should incorporate new developments to achieve the greatest possible benefit for
patients.
The Infiniti Vision System is the newest addition to
Alcon’s line of phacoemulsification machines. It has
various options for lens removal including traditional
US, NeoSoniX, AquaLase, and torsional OZil. NeoSoniX was introduced as an upgrade to the Alcon
Legacy; in addition to conventional US phacoemulsification, the NeoSoniX option adds oscillations up to 2
degrees at an approximate frequency of 100 Hz. The
addition of oscillatory movement improves surgeon
control and occlusion management and enhances cutting performance, allowing lower energy production,
with a resultant lower risk for intraoperative damage,
and providing better surgical outcomes.11,14 Rather
than using mechanical US energy from a vibrating
phaco needle, the AquaLase handpiece uses warm
pulses of BSS to emulsify the lens material for aspiration.15,16 AquaLase potentially reduces the risk for
damage to intraocular tissues because the fluid pulses
are quickly dampened in the eye’s fluid environment.
This effect rapidly diminishes elsewhere in the eye;
thus, there is no radiating US pressure wave. The other
fundamental difference between AquaLase and conventional US phacoemulsification is that there is no
possibility of an incision burn from AquaLase. In conventional US lens removal, thermal tissue damage at
the incision site is a potential complication with significant sequelae.17,18 The solution used by AquaLase is
warmed to 57 C, and experimental measurement of
internal wound temperature has shown that no incision heat is generated, even at full power.16 The softer
AquaLase tip is more capsule friendly, and there is
a decreased risk for posterior capsule rupture.
We have been using the Infiniti Vision System
since July 2004. Based on our experience, the learning
curve for AquaLase is short for experienced US
Table 1B. NeoSoniX settings by cataract grade.
Cataract Grade
1
2
3
4
Fixed Burst
(% for ms)
NeoSoniX Amplitude (%)
Fluidics (cm), Fixed Flow (cc/min),
Fixed Vacuum (mm Hg)
Dynamic Rise
25 for 50
30 for 20
50 for 20
70 for 80
50
60
70
80
60, 36, 400
90, 40, 550
90, 40, 600
100, 40, 650C
3
3
3
4
J CATARACT REFRACT SURG - VOL 34, MARCH 2008
380
EFFECT OF AQUALASE AND NEOSONIX ON CORNEAL ENDOTHELIUM
30
2,900
ECC (cells/mm2)
25
number of eyes
group A AquaLase
nuclear grade 1
nuclear grade 2
nuclear grade 3
nuclear grade 4
20
15
10
2,800
group A NeoSoniX
2,700
group B AquaLase
group B NeoSoniX
2,600
2,500
2,400
2,300
2,200
5
2,100
2,000
0
group A
preop
groupB
1 week
1 month
3 months
6 months
Figure 1. Comparison of the nuclear density between AquaLase and
NeoSoniX.
Figure 2. Comparison of mean ECC values between AquaLase and
NeoSoniX preoperatively and postoperatively (ECC Z endothelial
cell count).
phacoemulsification surgeons. We routinely use the
quick-chop technique19 with NeoSoniX or OZil. We
found that AquaLase liquefaction is performed more
efficiently with prechopping of the nucleus. We found
that once the pieces are created, whether by grooving,
chopping, or prechopping, it is best to remove them
with as little tip motion as possible. This is achieved
using fixed flow and fixed vacuum to optimize
occlusion.
In the present study, both AquaLase and NeoSoniX
were safe and efficient methods of cataract removal.
There was minimal loss of endothelial cells and
changes in the corneal thickness after surgery in both
eyes of patients in both groups. Statistically significantly less postoperative endothelial cell loss and
pachymetry changes in elderly patients with harder
nuclei and primary disabled endothelium after
AquaLase cataract removal suggests this method is
‘‘friendly’’ to the corneal endothelium. Despite the
longer AquaLase time and higher number of pulses,
the results were better in eyes having AquaLase than
in eyes having NeoSoniX.
The only limitation of AquaLase we found is that it
is not as effective as NeoSoniX or OZil in eyes with
rock hard cataract (grade 5). The use of axial US energy
coupled with oscillations of the tip with NeoSoniX
appears more effective for these hard lenses. AquaLase
easily extracts all cataracts of grade 1 and 2 and efficiently removes dense cataracts (grade 3 and many
grade 4). For these reasons, eyes with black or brown
mature cataract (grade 5) were not included in this
study.
One reason we believe AquaLase performed so well
is the fluidics of the Infiniti Vision System. We were able
to safely use high vacuums (400 to 650C mm Hg) and
high flow rates (40 mL/min) with full occlusion of the
aspiration port.
We consider AquaLase a promising new technology. Because it is very difficult to rupture the posterior
capsule using AquaLase, the device is excellent for polishing the capsule and removing lens epithelial cells.
Although AquaLase is especially well suited to refractive lens procedures and pediatric cataract, extraction
of hard and dense nuclei is also possible.
Several studies20,21 have evaluated corneal endothelial cell injury during phacoemulsification with IOL
implantation. Operative factors associated with endothelial cell loss include older age, total amount of US
energy, high nucleus grade, greater infusion volume
and turbulence of the irrigating solution, ricocheting
of nuclear fragments, and IOL and/or instrument
contact. Ophthalmic viscosurgical devices play an
Table 2A. Median AquaLase values by cataract grade.
Table 2B. Median NeoSoniX values by cataract grade.
Median
Cataract
Grade
1
2
3
4
AquaLase
Time (s)
Number
of Pulses
Peak Vacuum
(mm Hg)
0.09
0.35
0.70
2.60
126
490
1180
3440
468.5
544.0
592.0
536.0
Median
Cataract
Grade
Median Phaco
Power (%)
Phaco
Time (s)
Peak Vacuum
(mm Hg)
20.45
29.75
42.00
2.30
6.95
8.10
493.5
550.5
595.0
1
2
3
J CATARACT REFRACT SURG - VOL 34, MARCH 2008
381
EFFECT OF AQUALASE AND NEOSONIX ON CORNEAL ENDOTHELIUM
0.9
585
group A AquaLase
group A NeoSoniX
group B AquaLase
group B NeoSoniX
580
0.8
0.7
570
mean BCVA
PACHYMETRY (µ)
575
565
560
555
550
group A AquaLase
group A NeoSoniX
group B AquaLase
group B NeoSoniX
0.6
0.5
0.4
0.3
0.2
545
0.1
540
0.0
535
preop
1 week
1 month
3 months
6 months
preop
1 week
1 month
3 months
6 months
Figure 3. Comparison of the pachymetry values between AquaLase
and NeoSoniX preoperatively and postoperatively.
Figure 5. Comparison of the mean BCVA values between AquaLase
and NeoSoniX preoperatively and postoperatively.
important role by protecting endothelial cells and
maintaining space in the anterior chamber or capsular
bag. Based on their physical properties, OVDs can be
divided into 2 groups: high viscosity cohesive and
low viscosity dispersive. Cohesive agents are good
at maintaining space, while dispersive agents are
retained better in the anterior chamber. In this study,
dispersive Viscoat was used for capsulorhexis creation
and cohesive Provisc for IOL insertion in all eyes to
create the same conditions for phacoemulsification
and allow comparison of the effect of the surgical
method on the endothelial cell loss.
In conclusion, based on the results in our study, we
consider AquaLase cataract extraction to be safe for
the endothelium, even in older patients with harder
cataracts and a lower ECC preoperatively.
group A
group B
0.900
0.800
0.700
REFERENCES
P-values
0.600
0.500
0.400
0.300
0.200
0.100
0.000
1w
1m
3m
6m
A
group A
group B
1.000
0.900
0.800
P-values
0.700
0.600
0.500
0.400
0.300
0.200
0.100
0.000
1w
1m
3m
6m
B
Figure 4. Statistical analysis of ECC (A) and pachymetry (B) showing
P values in both groups (paired t test) at each postoperative visit
(w Z week; m Z months).
1. Davison JA. Introduction to phacoemulsification. In: Koch PS,
Davison JA, eds, Textbook of Advanced Phacoemulsification
Techniques. Thorofare, NJ, Slack, 1991; 107–138
2. Buratto L. Cataract surgery development and techniques. In:
Buratto L, ed, Phacoemulsification; Principles and Techniques.
Thorofare, NJ, Slack, 1998; 3–20
3. Gimbel HV, Neuhann T. Development, advantages, and
methods of the continuous circular capsulorhexis technique.
J Cataract Refract Surg 1990; 16:31–37
4. Boyd BF. The Art and the Science of Cataract Surgery. El Dorado, Panama, Highlights of Ophthalmology International, 2001;
409–411
5. Osher RH. Microcoaxial phacoemulsification. Part 2: clinical
study. J Cataract Refract Surg 2007; 33:408–412
6. Braga-Mele R, Khan BU. Hydro-chop technique for soft lenses.
J Cataract Refract Surg 2006; 32:18–21
7. Liu Y, Zeng M, Liu X, et al. Torsional mode versus conventional
ultrasound mode phacoemulsification; randomized comparative
clinical study. J Cataract Refract Surg 2007; 33:287–292
8. Fine IH, Packer M, Hoffman RS. Use of power modulations in
phacoemulsification; choo-choo chop and flip phacoemulsification. J Cataract Refract Surg 2001; 27:188–197
9. Fine IH, Packer M, Hoffman RS. New phacoemulsification technologies. J Cataract Refract Surg 2002; 28:1054–1060
10. Fine IH, Packer M, Hoffman RS. Power modulations in new phacoemulsification technology: improved outcomes. J Cataract
Refract Surg 2004; 30:1014–1019
11. Vasavada AR, Raj SM, Lee YC. NeoSoniX ultrasound versus ultrasound alone for phacoemulsification; randomized clinical trial.
J Cataract Refract Surg 2004; 30:2332–2335
J CATARACT REFRACT SURG - VOL 34, MARCH 2008
382
EFFECT OF AQUALASE AND NEOSONIX ON CORNEAL ENDOTHELIUM
12. Banko A, Kelman CD, inventors. Cavitron Corporation assignee.
Material removal apparatus and method employing high frequency vibrations. US patent 3589 363. July 25, 1967
13. Kelman CD. In tune with the father of phacoemulsification. J Cataract Refract Surg 1997; 23:1128–1129
14. Jirásková N, Rozsı́val P. Phacoemulsification parameters: Series 20000 Legacy versus Legacy with AdvanTec software and
NeoSoniX handpiece. J Cataract Refract Surg 2004; 30:144–
148
15. Hoffman RS, Fine IH, Packer M. New phacoemulsification technology. Curr Opin Ophthalmol 2005; 16:38–43
16. Mackool RJ, Brint SF. AquaLase: a new technology for cataract
extraction. Curr Opin Ophthalmol 2004; 15:40–43
17. Bissen-Miyajima H, Shimmura S, Tsubota K. Thermal effect on
corneal incisions with different phacoemulsification ultrasonic
tips. J Cataract Refract Surg 1999; 25:60–64
18. Mackool RJ. Incision burns [letter]. J Cataract Refract Surg
2003; 29:233–235
19. Tello A. History of the quick-chop technique [letter]. J Cataract
Refract Surg 2006; 32:1594
20. Hayashi K, Hayashi H, Nakao F, Hayashi F. Risk factors for corneal endothelial injury during phacoemulsification. J Cataract
Refract Surg 1996; 22:1079–1084
21. Miyata K, Maruoka S, Nakahara M, et al. Corneal endothelial cell
protection during phacoemulsification; low- versus high-molecular-weight sodium hyaluronate. J Cataract Refract Surg 2002;
28:1557–1560
J CATARACT REFRACT SURG - VOL 34, MARCH 2008
First author:
Nada Jirásková, MD, PhD
Department of Ophthalmology, University
Hospital, Hradec Králové, Czech Republic