1. Comparison between phaco-chop, divide-conquer and stop & chop phaco-technique according to the cataract density
Hae ri Yum, M.D., Man Soo Kim, M.D.
Eun Chul Kim, M.D.
Department of Ophthalmology and Visual Science,
The Catholic University of Korea
No author has any financial or proprietary interest
in any materials or methods mentioned

2. Introduction Phacoemulsification was the technique that was
performed in almost all cataract surgery.
When phacoemulsification was first introduced,
the nucleus was not divided and the phaco-
emulsification probe was used to sculpt and
consume the nucleus.
Compared with extracapsular cataract extraction,
phacoemulsification in associated with additional
potential risks of corneal endothelial cell damage.

3. Purpose
To compare the intraoperative and short-term postoperative outcomes of cataract surgery performed with 3 different types of the phaco-technique (phaco-chop, divide-conquer and stop & chop) under microcoaxial or conventional cataract surgery according to the cataract density.

4. Materials & Methods Cataract density (NO2 ,NO3, NO4) Phaco-Chop
90 cataract eyes with nuclear density from Grade 2 to 4
Cataract density
(NO2 ,NO3, NO4)
Phaco-Chop
Divide-Conquer
Stop & Chop

5. Materials & Methods Intraoperative measurements Clinical measurements
Effective phacoemulsification time (EPT)
Mean cumulative dissipated ultrasound energy (CDE)
Total balanced salt solution (BSS) use
Clinical measurements
Preoperative, 1-day postoperative, 1,2-month postoperative
Best corrected visual acuity (BCVA)
Central corneal thickness
Endothelial cell count

6. <Baseline preoperative clinical data>
Results
<Baseline preoperative clinical data>
Group 1 (Phaco-Chop)
(n=30)
Group 2 (Divide-Conquer)
Group 3 (Stop & Chop)
NO2
NO3
NO4
Mean age (y)
62.1±7.0
69.4±6.8
72.6±7.3
61.3±8.3
67.3±10.2
70.9±7.9
67.7±9.2
69.8±9.3
68.2±16.0
Preoperative visual acuity
(lod MAR)
0.39±0.33
0.27±0.05
0.24±0.14
0.28±0.14
0.30±0.14
0.22±0.11
0.26±0.22
0.34±0.16
0.19±0.18
Preoperative corneal thickness (μm)
517±18.5
526±11.0
526±9.0
522±15.6
522±12.4
523±12.5
519±11.6
520±15.8
523±12.4
Preoperative endothelial cell count
2655±333
2632±315
2460±336
2744±405
2330±543
2633±303
2319±278
2697±304
2480±367
 No significant difference between groups

7. <intra-op./EPT, CDE, BSS use>
Results
<intra-op./EPT, CDE, BSS use>
EPT(sec)
P value
<0.001
0.009
*Tukey HSD and Duncan test
CDE(%)
P value
0.003
0.033
*Tukey HSD and Duncan test
BSS use (ml)
0.017
P value
*Tukey HSD and Duncan test
0.048
The phaco-chop technique can provide more effective lens removal than divide-conquer and stop & chop phaco technique with lower phacoemulsification time and energy in the mature cataract.
EPT: effective phacoemulsification time
CDE: mean cumulative dissipated ultrasound energy
BSS: balanced salt solution

8. Results Endothelial cell count loss rate (%) Nuclear opacity
*Tukey HSD and Duncan test
Although the mean endothelial cell loss was less in phaco-chop groups than those in divide-conquer and stop & chop groups , the difference between groups was not significant statistically.

9. Results CCT change (%) Nuclear opacity
*Tukey HSD and Duncan test
CCT: central corneal thickness (μm)
Although the central corneal thickness increased after phacoemulsification , there was less change in phaco-chop than divide-conquer and stop & chop , the difference was not significant.

10. <BCVA (best corrected visual acuity)>
Results
<BCVA (best corrected visual acuity)>
Group 1 (Phaco-Chop)
(n=30)
Group 2 (Divide-Conquer)
Group 3 (Stop & Chop)
NO2
NO3
NO4
Pre op.
0.39±0.33
0.27±0.05
0.24±0.14
0.28±0.14
0.30±0.14
0.23±0.11
0.26±0.22
0.34±0.16
0.19±0.18
1 day
0.85±0.18
0.75±0.16
0.75±0.28
0.77±0.19
0.70±0.25
0.71±0.29
0.66±0.21
0.63±0.17
1 month
0.87±0.16
0.78±0.12
0.77±0.14
0.77±0.26
0.78±0.18
0.72±0.22
0.81±0.18
0.73±0.15
2 month
0.91±0.10
0.87±0.11
0.85±0.09
0.85±0.14
0.87±0.08
0.87±0.12
0.88±0.10
0.86±0.12
 No significant difference between groups

11. Conclusion
The phaco-chop technique can provide more effective lens removal than divide-conquer with lower phacoemulsification time and energy in the mature cataract.
However, the phaco-chop, divide-conquer and stop & chop technique may be all effective for both of microcoaxial and conventional incision cataract surgery.
There is an advantage of phaco-chop over divide-conquer and stop & chop in both CCT and ECC change but this advantage is no significant difference statistically.