Slide 1

Report
Comparing Factors Affecting
Surgically Induced Astigmatism
After Phacoemulsfication
Colin SH Tan1,2, Francine P. Yang1, Hon Kiat Wong1
1Department
2
of Ophthalmology, Tan Tock Seng Hospital, Singapore
Doheny Eye Institute, University of Southern California, USA
The authors have no financial interest in the subject matter of this e-poster
Introduction
• With continuous advances in cataract surgery, patients’ have
higher expectations of surgical and visual outcomes
• Astigmatism has considerable impact on quality of vision
and has been shown to significantly affect patients’
satisfaction with the postoperative outcome
• Astigmatism is affected by surgical technique, the type and
size of the corneal incision, and wound location
• Some surgeons perform a 3-plane clear corneal incision
during phacoemulsification as it is believed to have a greater
impact on astigmatic correction and also wound stability
compared to the standard phaco incision
Objectives
Our study aimed to review the surgically-induced astigmatism
during phacoemulsification and correlate it the following factors:
1. Wound type – 3-plane vs. 2-plane incisions
2. Wound location – along the steep axis of astigmatism or
elsewhere
3. The use of sutures to close the wound
Methods
• A review of 53 consecutive cases of phacoemulsification performed by a
single surgeon at the National Healthcare Group Eye Institute,
Singapore.
• A 3-plane incision was performed using a microkeratome to make a
50% corneal thickness incision, followed by a shelving incision similar to
the 2-plane incision
• In all surgeries, the following were standardized:
• 2.65 mm clear corneal wound
• Phacoemulsification system (Signature, Abbott Medical Optics, USA)
• 3-piece Acrylic lens (Sensar AR40e, Abbott Medical Optics, USA)
• Surgically induced astigmatism was calculated using vector analysis
Results
Mean age
(yrs)
Gender
Male
Female
3-plane
incision
2-plane
incision
p
value
69.4 (± 7.4)
66.6 (± 9.4)
0.230
19 (57.6%)
14 (42.4%)
10 (50.0%
10 (50.0%)
0.776
• There were no significant
differences between patients
in the 3-plane incision and 2plane incision groups
• Mean age of the patients was
68.3 ± 8.2 years (range, 50 95 )
• The overall mean surgically-induced astigmatism was 0.72D ±
0.61
• There were no cases of post-operative wound leak in either the
2- or 3-plane incision groups
Comparison of astigmatism between
2- and 3-plane incisions
• Surgically-induced astigmatism was lower in 3-plane compared
to 2-plane corneal incisions
• The trend was seen in patients with both low and high preoperative astigmatism
P=0.003
P=0.81
Wound sutures and axis of astigmatism
• Sutures significantly affected post-operative astigmatism:
In eyes where the corneal wound was sutured, the mean
surgically-induced astigmatism was significantly higher
compared to eyes without sutures (1.61D vs. 0.68D, P=0.01)
• There was no significant difference in astigmatism between
incisions made along the steep meridian (25/53 eyes) or incisions
made elsewhere (28/53 eyes) (0.71D vs. 0.73D, P=0.91)
Effects of demographics on astigmatism
0.75
0.8
0.7
There was no significant
difference in surgically induced
astigmatism between males
and females
0.61
0.6
P=0.15
0.5
0.4
0.3
0.2
0.1
0
Males
0.9
SIA was higher in the left eye
compared to the right eye,
although the results were not
statistically significant.
Female
0.84
0.8
P=0.08
0.7
0.53
0.6
0.5
0.4
0.3
0.2
0.1
0.0
left eye
right eye
Discussion
• Some surgeons perform a 3-plane corneal incision because they feel
that it is structurally more stable and reduces the risk of postoperative
wound leak.
• Our results show an additional advantage of a 3-plane incision:
significantly lower surgically-induced astigmatism vs. a 2-plane incision.
•
This was especially evident in patients with lower pre-operative
astigmatism (0.49D vs. 1.07D, p=0.03)
• Although phacoemulsification incisions are normally self sealing, a
surgeon may sometimes elect to use a suture if there is doubt about
wound stability or if the patient requires laser photocoagulation soon after
surgery. Our study demonstrates that a suture placed at the wound has
a significant effect on post-operative astigmatism
•
The effect of sutures should be considered in terms of astigmatic control
Discussion
• There is limited information in the current ophthalmic literature on the
factors affecting post-operative astigmatism in phacoemulsification.
• In a review, Batlan1 stated that, “Decreasing SIA has been a major goal
in the advancement of cataract surgery” and recommended the
selection of incision type and location, and consideration of preoperative
astigmatism to minimize postoperative astigmatism
• Studies have reported factors affecting surgically-induced astigmatism
(SIA):
• SIA is higher in clear corneal incision vs corneoscleral incision 2
• Smaller incisions cause less SIA compared to larger incisions 2,3,4
• Temporal placed incisions have lesser SIA versus superiorly placed
incisions2 (for preoperative against the rule astigmatism)
1. Batlan et al, Curr Opin Ophthal 1996
2. Nielsen PJ et al, JCRS 1995
3. Kohnen T et al, JCRS 1995
4. Pfleger T et al, JCRS 1996
Discussion
Additional studies have shown that:
• Clear corneal incision results in higher SIA only in larger incisions (3 mm vs. 2
mm) compared to scleral incisions (Hayashi et al)
• 2.2 mm micro-coaxial incisions have lower SIA compared to traditional 3 mm
clear-corneal incisions (Masket et al)
• There was no significant differences in resultant astigmatism when comparing
phaco vs. vitrectomy vs. both procedures together (Yuen et al)
• In a study evaluating factors affecting postoperative astigmatism, Cho et al
concluded that different strategies were required for different groups of
patients (classified by pre-operative astigmatism)
To our knowledge, the effect of a 3- vs. 2-plane corneal incision
have not previously been reported, demonstrating the myriad
factors which impact surgically-induced astigmatism
5. Hayashi et al, Ophthalmol 2010
6. Masket et al, JCRS 2009
7. Yuen et al, Eye 2009
8. Cho et al, Kor J Oph 1996
Conclusion
Our study has demonstrated that:
• A 3-plane cornea wound incision results in significantly lower
surgically-induced astigmatism compared to a 2-plane wound.
• Wound sutures result in significantly higher astigmatism
Taking into account our review of previously established risk
factors, it is clear that further research is required to design
models to determine best individualized management to
reduce postoperative astigmatism

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