University of Florence

1

• University of Florence
• Oto-Neuro-Ophthalmological Department
• Eye Institute

Alessandro Franchini MD
Understanding IOP Changes During
Phacoemulsification
One of the main unwanted phenomena which may
occur during cataract surgery is the post
occlusive surge which arises when the occlusion
is broken .As a result there is an immediate
decrease in the intraocular tension with the
collapse of the anterior chamber along with all
other connected complications. Obviously all the
companies producing phacoemulsificators have in
recent years taken all the necessary precautions
to avoid the post occlusive surge. This has been
done using relatively simple solutions like low
compliance tubes or modified phaco-tips or more
complex solutions that we can find in the
software of all the phaco of the last
generation. The decrease in the risk of post
occlusive surge has given us the opportunity to
work with ever increasing vacuum levels. This has
obliged us to use even higher irrigating flows
which in turn has meant increasing the bottle
height or even using a forced irrigation
system. Therefore if on one hand the risk of
hypotension has been reduced on the other hand
the risk of reaching excessive intraocular
tension during surgery has been increased. No
existing machine has the power to control this.
All the platforms on todays market are therefore
able to avoid the drop in anterior chamber
tension but are incapable of having an impact on
the maximum tension levels.
2
Materials and Methods
Even if todays surgical experience proves that
there are no important problems linked to the
intraoperative intraocular tension increase ,
many important papers show that even after small
incision cataract extraction there is an increase
in retinal thickness and an alteration of the
blood aqueous barrier which can persist for many
months after surgery. These problems can be
present in up to 100 of patients. The most
important cause of this is the surgical
fluctuation of the anterior chamber pressure
which determines an external and an internal
deformation of the anterior segment. This in turn
causes the retraction of the iris-lenticular
diaphragm and the elongation of the zonular
fibers and the ciliary process ,all of which
determine a continuous movement of the ciliary
body. Therefore the inevitable questions which
arise are which pressures are reached in the
anterior chamber during the various phases of
surgery and what kind of fluctuations can occur
? This study was carried out to measure the
anterior chamber fluctuations during
phacoemulsification. The anterior chamber tension
variations had never been studied continuously
in vivo during surgery in human eyes.
Tognetto D 54 Lobo CL 41 Eid T 30 Cagini
C 6 Parenti I 100 Biro Z 100
3
Materials and Methods
To measure intraocular tension we have adapted an
instrument (Codman Microsensor Skull Bolt
Kit). We are looking at an instrument used in
neurosurgery to continuously monitor the
intracranial pressure, which is formed by a
catheter with a micro silicon sensor mounted at
one end and an electrical connector at the other,
and it is interfaced with a Control Unit .The
sensor is located inside the anterior chamber
like an anterior chamber Maintainer through a
1-1.5 mm paracenthesis and it is kept in this
position throughout surgery.
4
Materials and Methods
We have carried out the simulation in three
groups of patients the first operated with a
standard coaxial phaco technique (through a 2.7
mm incision ),the second with an ultra-small
coaxial phaco (through a 2mm incision )and the
third with a bimanual technique (through two 1.4
mm incisions).
In all patients we have used the Sovereign
WhiteStar ICE machine with the settings that you
can see in this slide.
5
Results
We have measured the intraocular tension in four
different moments during surgery
TE gt 60 mmHg 42 of the surgical time TE
continuously gt 60 mmHg average 112 sec (167 max)
6
(No Transcript)
7
Discussion
However we can say that even if there are some
significant differences between the techniques
used the main concept of our study doesnt
change we always reach a far too high tension
increase and a far too high tension fluctuation
in anterior chamber. What can we do to avoid
this ? We can try to change some habits in
different phases. For example we can work on the
following aspects
8
Conclusions
We are therefore speak of defining a new surgical
philosophy which bears in mind not only the needs
of the anterior segment but also those of the
posterior segment. This is not as easy as it
seems since the anterior segment surgeon is often
unable to shift his mind beyond the iris plane.
References Ursell PG Cystoid macular edema after
phacoemulsification relationship to blood-aqueous
barrier damage and visual acuity JCRS
199925(11)1492-97 Miyake K Comparison of
Diclofenac and fluorometholone in preventing
cystoid macular edema after small incision
cataract surgery a multicentered prospective
trial Jpn J Ophthalmol.2000 44(1)58-67 El-Harazi
SM Consensual inflammation following ocular
surgeryOphthalmic Surg Lasers 1999
30(4)254-59 Lobo CL Macular alteration after
small-incision cataract surgery JCRS
200430(4)752-760 Schauersberger JB Long-term
disorders of BAB after small incision catract
surgery Eye 200014(1)61-63 Luo LX Disorders
of BAB after phacoemulsification Zhonghua Yan Ke
Za Zhi 200440(1)26-29 Tognetto D,Ravalico G.
Scanning laser polarimetry of nerve fiber layer
thickness in normal eyes after cataract
phacoemulsification and foldable intraocular lens
implantation JCRS 200531 (5)1042-1049 LIU Y
Macular image changes of OCT after
phacoemulsification Zhonghua Yan Ke Za Zhi
200238(5)265-267 Eid T Evaluation of macular
edema with optical coherence tomography after
phacoemulsification and intraoperative
sub-tenons injectionof triamcinolone acetonide
E.S.C.R.S, abstract book p.32.Lisbon 2005 Biro Z
Ticss changee of foveal and perifoveal area
measured by OCT after cataract surgery combined
with posterior CCC E.S.C.R.S, abstract book
p.14. Lisbon 2005 Cagini C Macular thickness
after cataract surgery measured by OCT
E.S.C.R.S, abstract book p.19.Lisbon 2005 Perente
I Evaluation of the macular effects of
uncomplicated phacoemulsification surgery by
optical coherence tomography E.S.C.R.S, abstract
book p.89. Lisbon 2005 Khng C,Packer M,Fine
H,HoffmanRS,MoreiraFB. Intraocular pressure
during Phacoemulsification. J Cataract Refract
Surg 2006 32 301-308