comparison of the effect of aqualase and neosonix phacoemulsification on the corneal endothelium

Comparison of the effect of AquaLaseand NeoSoniX phacoemulsification

on the corneal endotheliumNada Jiraskova, MD, PhD, Jana Kadlecova, MD, Pavel Rozsıval, MD, PhD,

Jana Nekolova, MD, Jana Pozlerova, MD, Zlatica Dubravska, MD

PURPOSE: To compare the extent of corneal endothelial cell loss and pachymetry changes in 2age-based groups of patients who had cataract removal by AquaLase (Alcon) phacoemulsificationin 1 eye and NeoSoniX (Alcon) phacoemulsification in the contralateral eye.

SETTING: Department of Ophthalmology, University Hospital, Hradec Kralove, 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 Aqua-Lase in the right eye and NeoSoniX in the left eye. The nuclei were graded clinically on the basis ofhardness. 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 usingthe paired t test.

RESULTS: In Group A, the differences in the postoperative changes in ECC and pachymetry betweenAquaLase and NeoSoniX were not statistically significant. In Group B, there were statisticallysignificant differences in postoperative changes in ECC and pachymetry, with the results betterin 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

ARTICLE

Phacoemulsification is now the preferred techniquefor cataract removal.1–4 Continuous improvement intechnology and technique have made cataract surgerysafer and more efficient.5–7 The quest for lens extrac-tion with reduced intraocular energy resulted inpowermodulations and supplemental energy sources,which have improved outcomes.8–10

Conventional ultrasound (US) phacoemulsificationis created in a handpiece when power is applied to pi-ezoelectric crystals that convert the electrical energyinto mechanical vibrations of the phaco needle. Thephaco needle tip is used to emulsify the lens materialat US frequencies generally between 25 KHz and62 KHz, which creates thermal and cavitational energythat has the potential to damage the cornea. The Neo-SoniX handpiece (Alcon) delivers oscillatory sonic andaxial US energy separately or in combination. The pha-co tip has a variable rotational oscillation up to 2 de-grees at an approximate frequency of 100 Hz. Thislower 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 withoscillatory motion is more efficient than axial energyalone.

The AquaLase liquefaction device (Alcon), one ofthe 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 pulsesare generated as current passes between electrodes.These pulses then travel from the handpiece into thetip of the instrument and eventually into the eye.The fluid pulses pass through a channel in the outersleeve of the tip and exit through a single small open-ing located in the lumen of the polymer application tipnear its distal end. Aspiration of the liquefied lens ma-terial occurs through the central lumen of the tip. TheBSS pulses are delivered at a maximum rate of 50 Hz,and the magnitude of the pulses can be linearly con-trolled by depressing the footpedal.

0886-3350/08/$dsee front matter 377doi:10.1016/j.jcrs.2007.10.033

378 EFFECT OF AQUALASE AND NEOSONIX ON CORNEAL ENDOTHELIUM

The purpose of this study was to evaluate the effectof AquaLase and NeoSoniX technology on cornealendothelial cells during phacoemulsification.

PATIENTS AND METHODS

This prospective clinical study included patients with bilat-eral lens opacification scheduled for cataract surgery at theDepartment of Ophthalmology, University Hospital, HradecKralove. Patients were selected from the department queue.For patients to be eligible for the study, both eyes had to havecataract, preferably with similar density grades. Patientswith ocular surface disease, endothelial or stromal cornealdystrophy, or corneal scars were excluded. The study pur-pose, procedures, and responsibilities were explained to allpotential participants, and informed consent was obtainedfrom all selected patients.

Patients were divided into 2 groups based on age. GroupA comprised patients younger than 80 years and Group B,patients 80 years or older.

Before surgery, a complete eye examination was per-formed. The examination included distance best correctedvisual acuity (BCVA) using Snellen optotypes, endothelialcell density (ECD), and pachymetry using a specular micro-scope (Noncon Robo Pachy SP-9000, Konan Medical). Cata-racts were graded clinically on the basis of hardnessaccording to the Buratto classification2 (1 to 5 scale). Patientswith a very hard nucleus (grade 5 to brown or black rockhard 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 sur-geon. Phacoemulsification was performed using topical an-esthesia, a 3.0 mm limbal incision, and AquaLase in theright eye and NeoSoniX in the left eye. The standard softpolymer needle (flared at the tip) with a 1.10mm inner diam-eter and 1.32 mm outer diameter was used in all AquaLasecases and a 30-degree round 1.10 mm flared ABS tip, in allNeoSoniX cases. The phaco settings were modified for eachcataract grade with both lens removal modalities (Tables 1Aand 1B). Sodium hyaluronate 3%–chondroitin sulfate 4%with sodium hyaluronate 1% (DuoVisc) was used as anophthalmic viscosurgical device (OVD) in all eyes. The dis-persive OVD (sodium hyaluronate 3.0%–chondroitin sulfate4.0% [Viscoat]) was used during creation of the capsulo-rhexis and the cohesive OVD (sodium hyaluronate 1.0%

Accepted for publication October 23, 2007.

From the Department of Ophthalmology, University Hospital,Hradec Kralove, Czech Republic.

No author has a financial or proprietary interest in any material ormethod mentioned.

Presented in part at the ASCRS Symposium on Cataract, IOL andRefractive Surgery, San Diego, California, USA, April 2007.

Supported in part by research project MZO 00179906 from theMinistry of Health, Prague, Czech Republic, and in part by a grantfrom Alcon, Fort Worth, Texas, USA.

Corresponding author: Nada Jiraskova, MD, PhD, Department ofOphthalmology, University Hospital, Sokolska 581, 500 05 HradecKralove, Czech Republic. E-mail: [email protected].

J CATARACT REFRACT SU

[Provisc]), for intraocular lens (IOL) insertion. In all eyes,a single-piece IOL (AcrySof, Alcon) was implanted in thebag using the Monarch II injector system. Postoperatively,all patients received topical tobramycin 3.0 mg/mL–dexa-methasone 1.0 mg/mL (TobraDex) 5 times daily for 2 weeksfollowed by dexamethasone 1.0 mg/mL 3 times daily for 2weeks.

Patients were examined 1 day, 1 week, and 1, 3, and 6months after surgery. At each visit, refractionwas performedand BCVAwas measured using Snellen optotypes. The ECDand pachymetry were evaluated 1 week and 1, 3, and 6months after surgery. The mean pachymetry and ECDvalues were calculated.

Statistical analysis of the postoperative changes in pachy-metry and endothelial cell count (ECC) between right eyesand left eyes in both groups was performed using the pairedt test. All mean values are reported with their standarddeviation.

RESULTS

The 56 patients were divided into 2 groups. The meanage in Group A (n = 28) (younger than 80 years) was63 years (range 50 to 65 years). The mean age in GroupB (n = 28) (80 years or older) was 83 years (range 80 to93 years). Group B had a higher frequency of hardernuclei (Figure 1). No eye having NeoSoniX phacoe-mulsification had a cataract of grade 4.

Phacoemulsification Parameters

AquaLase Table 2A shows the median phacoemulsi-fication values for AquaLase according to nucleargrade. 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 ofpulses ranged from 0 (soft lens; only irrigation/aspira-tion using high vacuum was used) to 5280 (hard cata-ract, grade 4). Themedian number of pulses was 493 inGroup A and 1410 in Group B.

Fixed flow and vacuum were used in all cases, witha dynamic rise of 2 or 3 (Table 1A). Themean peak vac-uumwas 537 G 77mmHg (median 542mmHg; range369 to 729 mmHg) in Group A and 520 G 118 mmHg(median 570 mm Hg; range 60 to 596 mm Hg) inGroup B.

NeoSoniX Table 2B shows the median phacoemulsifi-cation values for NeoSoniX according to nucleargrade. The median phaco power was 5.95% (range0% to 16.5%) in Group A and 5.00% (range 2.0% to21.0%) in Group B. The median effective phaco timewas 7.2 seconds (range 0 to 16.1 seconds) in Group Aand 7.0 seconds (range 1.3 to 22.6 seconds) in Group B.

Fixed flow and vacuum were used in all cases, witha dynamic rise of 3 or 4 (Table 1B). The mean peak vac-uumwas 532 G 77mmHg (median 548mmHg; range380 to 696 mm Hg) in Group A and 570 G 29 mm Hg

RG - VOL 34, MARCH 2008

mailto:[email protected]

379EFFECT OF AQUALASE AND NEOSONIX ON CORNEAL ENDOTHELIUM

Table 1A. AquaLase settings by cataract grade.

Cataract GradeLinear Magnitude

(% @ pps) Burst (%)Fluidics (cm), Fixed Flow (cc/min),

Fixed Vacuum (mm Hg) Dynamic Rise

1 60 @ 40 50 96, 36, 500 22 80 @ 50 50 100, 40, 550 23 100 @ 50 50 105, 40, 600 34 100 @ 50 70 105, 40, 650C 3

pps Z pulses per second

(median 553 mm Hg; range 545 to 625 mm Hg) inGroup B.

Surgical Outcomes

Figure 2 shows the mean ECC values and Figure 3shows the mean pachymetry values in Group A andGroup B preoperatively as well as 1 week and 1, 3,and 6 months postoperatively. In Group A, the differ-ences in postoperative changes in ECC and pachyme-try between the right eye (AquaLase) and left eye(NeoSoniX) were not statistically significant. In GroupB, there were statistically significant differences inpostoperative changes in ECC and pachymetry, withthe results better in AquaLase eyes. Figure 4 showsthe P value for ECC (A) and pachymetry (B) in bothgroups at each postoperative visit.

The BCVA improved in all eyes immediately aftersurgery and remained stable during the entire fol-low-up (Figure 5). In Group B, 16 patients (57%) hadincipient age-related macular degeneration, whichwas the cause of the worse results in this group.

DISCUSSION

The art and science of cataract removal by Kelman USphacoemulsification12,13 are continually evolving. Im-provements in technique and technology have madethe procedure safer and more efficient than in thepast. Each surgeon should incorporate new develop-ments to achieve the greatest possible benefit forpatients.

The Infiniti Vision System is the newest addition toAlcon’s line of phacoemulsification machines. It has

various options for lens removal including traditionalUS, NeoSoniX, AquaLase, and torsional OZil. Neo-SoniX was introduced as an upgrade to the AlconLegacy; in addition to conventional US phacoemulsifi-cation, the NeoSoniX option adds oscillations up to 2degrees at an approximate frequency of 100 Hz. Theaddition of oscillatory movement improves surgeoncontrol and occlusion management and enhances cut-ting performance, allowing lower energy production,with a resultant lower risk for intraoperative damage,and providing better surgical outcomes.11,14 Ratherthan using mechanical US energy from a vibratingphaco needle, the AquaLase handpiece uses warmpulses of BSS to emulsify the lens material for aspira-tion.15,16 AquaLase potentially reduces the risk fordamage to intraocular tissues because the fluid pulsesare 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 otherfundamental difference between AquaLase and con-ventional US phacoemulsification is that there is nopossibility of an incision burn from AquaLase. In con-ventional US lens removal, thermal tissue damage atthe incision site is a potential complication with signif-icant sequelae.17,18 The solution used by AquaLase iswarmed to 57�C, and experimental measurement ofinternal wound temperature has shown that no inci-sion heat is generated, even at full power.16 The softerAquaLase tip is more capsule friendly, and there isa decreased risk for posterior capsule rupture.

We have been using the Infiniti Vision Systemsince July 2004. Based on our experience, the learningcurve for AquaLase is short for experienced US

Table 1B. NeoSoniX settings by cataract grade.

Cataract GradeFixed Burst(% for ms) NeoSoniX Amplitude (%)

Fluidics (cm), Fixed Flow (cc/min),Fixed Vacuum (mm Hg) Dynamic Rise

1 25 for 50 50 60, 36, 400 32 30 for 20 60 90, 40, 550 33 50 for 20 70 90, 40, 600 34 70 for 80 80 100, 40, 650C 4

J CATARACT REFRACT SURG - VOL 34, MARCH 2008


phacoemulsification surgeons. We routinely use thequick-chop technique19 with NeoSoniX or OZil. Wefound that AquaLase liquefaction is performed moreefficiently with prechopping of the nucleus. We foundthat once the pieces are created, whether by grooving,chopping, or prechopping, it is best to remove themwith as little tip motion as possible. This is achievedusing fixed flow and fixed vacuum to optimizeocclusion.

In the present study, both AquaLase and NeoSoniXwere safe and efficient methods of cataract removal.There was minimal loss of endothelial cells andchanges in the corneal thickness after surgery in botheyes of patients in both groups. Statistically signifi-cantly less postoperative endothelial cell loss andpachymetry changes in elderly patients with hardernuclei and primary disabled endothelium afterAquaLase cataract removal suggests this method is‘‘friendly’’ to the corneal endothelium. Despite thelonger AquaLase time and higher number of pulses,the results were better in eyes having AquaLase thanin eyes having NeoSoniX.

The only limitation of AquaLase we found is that itis not as effective as NeoSoniX or OZil in eyes withrock hard cataract (grade 5). The use of axial US energycoupled with oscillations of the tip with NeoSoniX

0

5

10

15

20

25

30

group A groupB

nu

mb

er o

f eyes

nuclear grade 1nuclear grade 2nuclear grade 3nuclear grade 4

Figure 1. Comparison of the nuclear density between AquaLase andNeoSoniX.

Table 2A. Median AquaLase values by cataract grade.

Median

CataractGrade

AquaLaseTime (s)

Numberof Pulses

Peak Vacuum(mm Hg)

1 0.09 126 468.52 0.35 490 544.03 0.70 1180 592.04 2.60 3440 536.0

J CATARACT REFRACT SUR

appearsmore effective for these hard lenses. AquaLaseeasily extracts all cataracts of grade 1 and 2 and effi-ciently removes dense cataracts (grade 3 and manygrade 4). For these reasons, eyes with black or brownmature cataract (grade 5) were not included in thisstudy.

One reason we believe AquaLase performed so wellis the fluidics of the InfinitiVision System.Wewere ableto safely use high vacuums (400 to 650C mmHg) andhigh flow rates (40 mL/min) with full occlusion of theaspiration port.

We consider AquaLase a promising new technol-ogy. Because it is very difficult to rupture the posteriorcapsule usingAquaLase, the device is excellent for pol-ishing the capsule and removing lens epithelial cells.Although AquaLase is especially well suited to refrac-tive lens procedures and pediatric cataract, extractionof hard and dense nuclei is also possible.

Several studies20,21 have evaluated corneal endothe-lial cell injury during phacoemulsification with IOLimplantation. Operative factors associated with endo-thelial cell loss include older age, total amount of USenergy, high nucleus grade, greater infusion volumeand turbulence of the irrigating solution, ricochetingof nuclear fragments, and IOL and/or instrumentcontact. Ophthalmic viscosurgical devices play an

2,000

2,100

2,200

2,300

2,400

2,500

2,600

2,700

2,800

2,900

preop 1 week 1 month 3 months 6 months

EC

C (cells/m

m2)

group A AquaLasegroup A NeoSoniXgroup B AquaLasegroup B NeoSoniX

Figure 2. Comparison of mean ECC values between AquaLase andNeoSoniX preoperatively and postoperatively (ECC Z endothelialcell count).

Table 2B. Median NeoSoniX values by cataract grade.

Median

CataractGrade

Median PhacoPower (%)

PhacoTime (s)

Peak Vacuum(mm Hg)

1 20.45 2.30 493.52 29.75 6.95 550.53 42.00 8.10 595.0

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381EFFECT OF AQUALASE AND NEOSONIX ON CORNEAL ENDOTHELIUM

important role by protecting endothelial cells andmaintaining space in the anterior chamber or capsularbag. Based on their physical properties, OVDs can bedivided into 2 groups: high viscosity cohesive andlow viscosity dispersive. Cohesive agents are goodat maintaining space, while dispersive agents are

535

540

545

550

555

560

565

570

575

580

585


PA

CH

YM

ET

RY

(µ

)


Figure 3. Comparison of the pachymetry values between AquaLaseand NeoSoniX preoperatively and postoperatively.

0.000

0.100

0.200

0.300

0.400

0.500

0.600

0.700

0.800

0.900

P-valu

es

1w 1m 3m 6m

group Agroup B

A

0.000

0.100

0.200

0.300

0.400

0.500

0.600

0.700

0.800

0.900

1.000

P-valu

es

1w 1m 3m 6m

group Agroup B

B

Figure 4. Statistical analysis of ECC (A) and pachymetry (B) showingP values in both groups (paired t test) at each postoperative visit(w Z week; m Z months).


retained better in the anterior chamber. In this study,dispersive Viscoat was used for capsulorhexis creationand cohesive Provisc for IOL insertion in all eyes tocreate the same conditions for phacoemulsificationand allow comparison of the effect of the surgicalmethod on the endothelial cell loss.

In conclusion, based on the results in our study, weconsider AquaLase cataract extraction to be safe forthe endothelium, even in older patients with hardercataracts and a lower ECC preoperatively.

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0.0

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Figure 5. Comparison of the mean BCVA values between AquaLaseand NeoSoniX preoperatively and postoperatively.



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First author:Nada Jiraskova, MD, PhD

Department of Ophthalmology, UniversityHospital, Hradec Kralove, Czech Republic


comparison of the effect of aqualase and neosonix phacoemulsification on the corneal endothelium

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