1. Continuous-Mode Versus Custom-Pulse Mode Phacoemulsification of Hard Nucleus
Young Jeung Park, M.D. Ph.D.
Won Suk Choi, M.D.
Kyoo Won Lee, M.D. Ph.D.
Cheil Eye Hospital , Daegu, Korea
Financial Disclosure: All authors declares no financial interest
2010 ASCRS Annual Meeting, Boston, Massachusetts

2. Background and purpose
OZil® continuous mode has following advantages: Reduction of repulsion and chattering during phacoemulsification resulting in increased efficacy , and reduction of tissue damage by reducing heat generation.
There are some reports describing the superiority of Ozil ® torsional phacoemulsification over conventional phacoemulsification in soft~ medium-hard nucleus.
In case of hard nucleus, Ozil ® torsional phacoemulsification presents disadvantages due to difficulty in initial impalement, resulting in difficult chopping, and induces clogging effect during phacoemulsification.
Ozil ® custom pulse mode is conventional phacoemulsification mixed into the main mechanism of Ozil ® torsional mode
To compare short-term post-operative results in OZil ® continuous mode versus OZil ® custom pulse mode phacoemulsification in cataract patients with hard nucleus.

3. Materials and Methods Prospective study
Patients having cataract with Lens Opacities Classification System III( above NO5,NC5) and a corneal endothelial count greater than 2000 cells/mm2 (49 patients, 53 eyes)
Patients were excluded if they had other eye or general disorders affecting their vision; eg, diabetic retinopathy, glaucoma, uveitis, or previous intraocular surgery.
Phaco system: OZil ®, Infiniti Vision System, Alcon Labs
Group 1: OZil ® continuous mode in 24 patients (25 eyes)
Group 2: OZil ® custom pulse mode in 25 patients (29 eyes)
All surgeries were performed by the one surgeon with lots of experience (Y J Park).
Chylack LT, et al. The Lens Opacities Classification System III.
The Longitudinal Study of Cataract Study Group. Arch Ophthalmol Jun;111(6):831-6.

4. Evaluations
US time (UST), US%, aspiration time, estimated fluid used, and cumulative dissipated energy (CDE) were compared in the above two groups.
Post-op central corneal thickness (CCT), endothelial cell count, and corneal clarity were compared at pre-op, 1day, 3days post-op, 1 week, 2weeks, 1month, 2months, and 3month post-op.
Statistics: Mann-Whitney U-test: p˂ 0.05

5. Surgical parameters used in the study with Infiniti phacoemulsification platform
Group 1†
Group 2‡
Incision size (mm)
2.8
Continuous capsulorrhexis diameter (mm)
Phacoemulsification tip(0.9mm micorotip ABS)
Mini-flared 45° Kelman ,Bevel down
Mini-flared 45° Kelman, Bevel down
Chopping technique
Counter prechop + Horizontal chop
Viscoelastic material(OVD): Hyal 2000®‡
1% sodium hyaluronate
Settings
Phaco Power (%) / Torsional amplitude (%)
• / 100
30~60 / 100
Aspiration flow (cm3/minute) 35
Vacuum (mmHg)
400
Mode/dynamic rise
Continuous /0
Custom-pulse/0
Phaco (on/off) (msec) •
50 / 0
Ultrasonic oscillations (on/off) (msec)
150 / 0
† Group 1= OZil ® continuous mode phacoemulsification
‡ Group 2= OZil ® custom pulse mode phacoemulsification
# Hyal 2000 ®, LG life science, Korea

6. Results Patients characteristics
(mean±SD)
Group 1†
Group 2‡
p-value§
Eye(Patients)
25(24)
29(25)
0.36
Gender (male / female)
10 / 14
5 / 20
0.98
AGE (range) (years)
77.1±8.7 (60~97)
75.5±9.4(56~94)
Mean nucleus density
5.3±0.5
Central corneal thickness(µm)
531.7±28.6
526.5±31.8
0.44
Endothelial cell count(cell/mm2 )
2472±371
2514±302
0.78
Comparison of mean surgical parameters between OZil ® continuous mode and OZil ® custom pulse mode
(mean±SD)
Group 1†
Group 2‡
p-value§
US§ time (sec)
125.7
±49.2
96.3
±58.2
0.01
US %
25.3
± 2.2
27.5
±5.4
0.14
CDE∏ (sec)
32.7
±14.4
23.6
±17.8
0.03
Aspiration time (sec)
313.9
±123.6
245.6
±131.6
Estimated fluid used (cc)
114.7
±46.1
92.1
±49.6
0.04
† Group 1= OZil ® continuous mode phacoemulsification
‡ Group 2= OZil ® custom pulse mode phacoemulsification
§ Mann-Whitney U-test ; § US=ultrasound
∏ CDE=cumulative dissipated energy = torsional amplitude x torsional timex0.4

7. Results Patients characteristics
(mean±SD)
Group 1†
Group 2‡
p-value§
Eye(Patients)
25(24)
29(25)
0.36
Gender (male / female)
10 / 14
5 / 20
0.98
AGE (range) (years)
77.1±8.7 (60~97)
75.5±9.4(56~94)
Mean nucleus density
5.3±0.5
Central corneal thickness(µm)
531.7±28.6
526.5±31.8
0.44
Endothelial cell count(cell/mm2 )
2472±371
2514±302
0.78
Comparison of mean surgical parameters between OZil ® continuous mode and OZil ® custom pulse mode
(mean±SD)
Group 1†
Group 2‡
p-value§
US§ time (sec)
125.7
±49.2
96.3
±58.2
0.01
US %
25.3
± 2.2
27.5
±5.4
0.14
CDE∏ (sec)
32.7
±14.4
23.6
±17.8
0.03
Aspiration time (sec)
313.9
±123.6
245.6
±131.6
Estimated fluid used (cc)
114.7
±46.1
92.1
±49.6
0.04
† Group 1= OZil ® continuous mode phacoemulsification
‡ Group 2= OZil ® custom pulse mode phacoemulsification
§ Mann-Whitney U-test ; § US=ultrasound
∏ CDE=cumulative dissipated energy = torsional amplitude x torsional timex0.4

8. Difference between preoperative and postoperative changes in central corneal thickness(CCT)
(mean±SD)
Pre-op
Post-op
1day
3days
1week
2weeks
1month
2months
3months
Group 1†
µm/(∆* %)
531.7±28.6
596.4±78.2
(+12.0)
575.2±46.9
(+8.1)
564.3±49.1
(+6.0)
561.2±44.1
(+5.5)
541.3±34.1
(+1.8)
526.6±28.5
(-0.8)
525.2±29.2
(-1.1)
Group 2‡
526.5±31.8
565.7±39.1
(+7.5)
560.4±41.5
(+6.4)
548.8±39.6
(+4.2)
546.4±39.8
(+3.8)
534.6±38.5
(+1.5)
515.6±35.2
(-1.9)
517.0±34.5
(-1.6)
P-value§
0.44
0.26
0.28
0.16
0.20
0.65
0.39
0.84
† Group 1= OZil ® continuous mode phacoemulsification
‡ Group 2= OZil ® custom pulse mode phacoemulsification
* Differences between pre-op and post-op changes in CCT; § Mann-Whitney U-test

9. Difference between preoperative and postoperative changes in endothelial cell count
(mean±SD)
Pre-op
Post-op
1day
3days
1week
2weeks
1month
2months
3months
Group 1†
cell/mm2( ∆* %)
2472±371
1966±498
(-20.0)
1978±534
(-19.9)
2002±545
(-18.9)
2000±481
(-19.1)
2050±466
(-16.6)
2076±478
(-15.6)
2074±525
(-15.7)
Group 2‡
2514±302
2194±357
(-12.7)
2232±435
(-11.2)
2250±396
(-10.3)
2186±396
(-13.1)
2215±423
(-12.0)
2148±388
(-13.7)
2218±392
P-value§
0.78
0.25
0.1
0.09
0.23
0.42
0.73
0.35 * *
(cell/mm2)
† Group 1= OZil ® continuous mode phacoemulsification;
‡ Group 2= OZil ® custom pulse mode phacoemulsification
* Differences between pre-op and post-op changes in endothelial cell count
§ Mann-Whitney U-test

10. Difference between preoperative and postoperative changes in Descemet’s folds
(mean±SD)
Post-op
1day
3days
1week
2weeks
1month
2months
3months
Group 1†
1.00±1.1
0.44±0.7
0.42±0.7
0.32±0.5
0.08±0.3
Group 2‡
0.37±0.6
0.14±0.4
0.12±0.4
P-value§
0.08
0.07
0.09
0.57
1.00 * * * *
† Group 1= OZil ® continuous mode phacoemulsification;
‡ Group 2= OZil ® custom pulse mode phacoemulsification
§ Mann-Whitney U-test
Descemet’s folds parameter : none (0), trace (1) , mild (2), moderate (3), severe (4)

11. Summary
OZil ® custom pulse mode group exhibited significantly lower UST, aspiration time, estimated fluid used, and CDE.
There were no significantly difference between the two groups in CCT increment, but OZil ® custom pulse mode group showed less CCT increase than OZil ® continuous mode group.
OZil ® custom pulse mode group had significantly less endothelial cell count decline at 1 day and 1 week post-op.
OZil ® custom pulse mode group had significantly lower corneal edema at 1 day ~ 2 weeks post-op.

12. Conclusion
In case of cataract surgeries involving hard nucleus(above NO5), the OZil® custom pulse mode used less ultrasound energy, and in turn reduced endothelial cell damage, leading to reduced corneal edema in early post-op period.
Therefore, in surgery involving hard nucleus OZil® custom pulse mode is recommended to induce faster visual rehabilitation after surgery