1. An Analysis of Wound Burns in the United States and Canada
Randall J Olson, MD
Clara Chan, MD
Michael Bradley, MD
Tyler Sorenson, MS4
Funded by an unrestricted grant from Abbott Medical Optics (Randall Olson is a consultant to this company)
From the John A Moran Eye Center at the University of Utah (Olson and Sorenson), The University of Toronto (Chan) and the University of Rochester (Bradley)

2. Bradley AJO 2006;141:222 A wound burn survey of the Western US.
76581 surgeries with a wound burn incidence of about 1 per 1000.
Approach from 1.3/1000(D & C) to 0.26/1000 (Vertical chop; p=0.003)
Machine from 1.2/1000 (Legacy) to 0.56/1000 (Sovereign; p=0.014)
Power from 1.76/1000 (continuous) to 0.26/1000 (hyperpulse; p<0.0001)
Multivariate analysis: Power followed by approach in importance.

3. Other wound burn in vitro work
JCRS 2006;32:1222 (OVD)
OVD + ultrasound = exothermic reaction
Most exothermic Viscoat (up to 6.3 x BSS) and Healon 5 (up to 5.2 x BSS; p< for both).
AJO (in press) on transversal ultrasound
Ozil 37% heat output of continuous (p<0.0001)
Ellips 42% heat output of OZil (aspiration blocked; p<0.0001)
Longitudinal friction additive

4. 2009 Wound burn survey in the US and canada
Web-site based survey launched Summer 2009.
Included machine, power modulation, approach, OVD, and incision size.
Both general use and specific use with wound burns recorded.
Worked through state and provincial societies.
All Ophthalmologists queried at least 3 times and 3 times more for any missing data.
multivariate analysis still being refined.

5. Wound burn & machines used
Machine Used
# of Wound Burns
# of Surgeries
Wound Burns per 1000 Surgeries
Legacy 96
154,562
0.62
Infiniti
187
455,507
0.41
Millennium 30
93,686
0.32
Sovereign 40
153,790
0.26
Signature 7
32,609
0.21
Stellaris 3
22,992
0.13
Legacy > than the rest (p<0.0001); Infiniti > than the rest minus Legacy (p=0.0009)

6. Wound burn & power modulation
# Wound Burns
# Surgeries
Wound Burn per 1000 Surgeries
Continuous 81
104,737
0.77
OZil + Long.
120
223,937
0.54
Burst 21
60,769
0.35
Pulse 32
104,761
0.31
OZil (alone) 60
215,314
0.28
Hyperpulse 45
199,959
0.23
Ellips +/- Long.
13,961
0.00
Continuous vs Burst, Pulse and Hyperpulse (P<0.0001); OZil vs OZil + Longitudinal ultrasound (P<0.0001); Ellips vs OZil +/- Longitudinal (P=0.017)

7. Wound burn & surgical approach
Divide & Conquer + Carousel vs all other approaches; P < Stop and Chop vs all other chopping approaches + phaco flip; P <
Surgical Approach
# Wound Burns
# Surgeries
Wound Burns per 1000 Surgeries
Carousel 9
12,026
0.75
Divide & Conq.
267
421,763
0.63
Stop & Chop 74
167,897
0.44
Vertical Chop 32
138,173
0.23
Phaco Flip 8
46,115
0.17
Horizont. Chop 15
118,234
0.13
Pre-Chop 2
38,231
0.05

8. Wound burns / 1000 Surgeries
Wound burn & OVD use
Healon 5 vs all but Viscoat/DuoVisc; P < Viscoat/DuoVisc vs all but Healon 5; P < Heaon 5 vs Viscoat/DuoVisc; P <
OVD Used
# Wound Burns
# Surgeries
Wound burns / 1000 Surgeries
Healon 5 38
14,275
2.7
Viscoat/DuoVisc
246
478,754
0.51
DisCoVisc 31
69,763
0.44
Provisc 25
57,008
Amvisc 14
36,941
0.38
Healon 15
60,931
0.25
Ocucoat 9
40,060
0.22
Amvisc Plus
76,523
0.20
Healon GV 7
54,026
0.13
Healon D/Vitrax
8,400
0.00

9. Wound burn & incision size
No significant differences
Incision Size
# Wound Burns
# Surgeries
Wound Burns per 1000 Cases
2.8mm or more
124
284,115
0.44
2.41 to 2.79mm
169
446,687
0.38
2.11 to 2.4mm 49
128,184
1.5 to 2.1mm 19
50,982
0.37

10. Other findings
The region with the lowest incidence of wound burn (Canada) had 51% of the wound burn rate of the highest incidence region (Northeastern US; P = ); however wound burn incidence was significantly lower with surgeons busier than the median (800 surgeries per year; P < ) and Canada had the highest percentage of busy surgeons of any region (74%).
Still working on filling in some key missing data points, but the data is 99% complete. With complete data a multivariate analysis will be most valuable. For instance Infiniti incidence (0.41/1000cases) is surely impacted by OZil + longitudinal incidence of 0.54/1000 cases with 223,937 surgeries.

11. CONCLUSIONS Overall wound burn incidence 50% less than 2006 AJO study.
In vitro work on OVDs and transversal does have support in this survey.
Differences in machine wound burn incidence certainly impacted by proprietary power modulations (multivariate analysis will sort this out).
Power modulation follows total heat production theory very closely.
Approach varied substantially and generally follows 2006 AJO paper.
Healon 5 followed by Viscoat increases wound burn risk.
Incision size does not appear to be a factor.