J. Biomedical Science and Engineering, 2010, 3, 727-734 JBiSE
doi:10.4236/jbise.2010.37097 Published Online July 2010 (http://www.SciRP.org/journal/jbise/).
Published Online July 2010 in SciRes. http://www.scirp.org/journal/jbise
Thermal analysis of different tips for various operating modes
of phacoemulsification system
Radin Tahvildari, Hanieh Fattahi, Ahmad Amjadi
Laser and Medical Physics Laboratory, Department of Physics, Sharif University of Technology, Tehran, Iran.
Received 16 April 2010; revised 15 May 2010; accepted 17 May 2010.
ABSTRACT
Cataract is an opacity that develops in the crystalline
lens of the eye, due to alteration in some of its protein
fibers, with the consequent impairment of visual acu-
ity. The most effective and common treatment is to
surgically remove the cloudy lens. In this process the
crystalline lens are removed and the eye’s refraction
power is restored by inserting an artificial lens. Pha-
coemulsification refers to modern cataract surgery in
which the eye’s internal lens is emulsified with an
ultrasonic hand piece, and aspirated from the eye.
Aspirated fluids are replaced with irrigation of bal-
anced salt solution, thus maintaining the anterior
chamber, as well as cooling the hand piece. The pa-
tient can be released soon after the operation. The
problem of this procedure in some cases is thermal
damage. This research addresses the aforementioned
problem through an important parameter, different
operating modes of the system. The proposed in-vitro
approach has been investigated in details.
Keywords: Cataract Surgery; Phacoemulsification;
Thermal Damages; In Vitro Measurement; Thermocouples
1. INTRODUCTION
When the natural lens of eye becomes cloudy, usually
because of the aging process, it keeps light rays from
passing through or diffuses the light in such a way that
vision becomes fuzzy or hazy. This cloudy lens is called
a cataract. The object of cataract surgery is to remove
this hazy lens and to replace it with a plastic prescription
lens that is permanently implanted in the eye.
At present, the most widely used surgical technique is
phacoemulsification, developed by Kelman (1967), in
which ultrasonic emissions are utilized to fragment the
crystalline lens inside the eye, the fragments then being
drawn out through a very small incision – about 2.8-3
mm – at the zone where the cornea meets the sclera. This
technique has several advantages such as faster surgical
times, smaller incisions which make healing times
quicker and increased surgeon control [2,3].
Three components constitute the heart of all phaco
systems which are irrigation, aspiration and ultrasound
[4].
The ultrasonic hand piece (Figure 1) incorporates a
transducer for converting high-frequency, alternating
current in to mechanical vibrations. By piezoelectric cry-
stals electrical energy converts to mechanical energy and
causes the hollow cylindrical tip attached to oscillate at
frequency around 40 KHz to break up (emulsify) the
cataract into tiny pieces [1,2].
The emulsified material is simultaneously suctioned
from the eye by the tip. The front (anterior) section of
the lens capsule is removed along with the fragments of
the natural lens. The back (posterior) portion of the cap-
sule is left in place to hold and maintain the correct posi-
tion for the implanted intraocular lenses.
2. DISCUSSION
2.1. Lead-In
With an increase in the use of phacoemulsification con-
cern about potential for thermal wound injuries during
surgery has increased [9]. Phacoemulsification requires
more attention to detail than any other ophthalmic sur-
gical procedure. The success of each step of the proce-
dure is critically dependent upon how well each previous
Figure 1. Phacoemusification hand piece.

R. Tahvildari et al. / J. Biomedical Science and Engineering 3 (2010) 727-734 728
step was performed. Errors early in the procedure will
almost inevitably result in subsequent problems.
The small incision is what gives phaco most its ad-
vantages but, as with all steps in phacoemulsification, it
must be fashioned very exactly [5].
The location, the size, the depth and configuration of
the incision are all very critical factors in determining
the final outcome in phaco.
In some cases burns can result in fusion of the cornea
or the sclera, damage the corneal endothelium, wound
gape and delayed wound healing.
It is important to note that the aim of this study is to
compare and analyze the changes of temperature around
the different tips for three operating modes of Sina
Phacoemulsification System (Figure 2) which is one of
the products of an Iranian medical engineering company
(Aali-Payam Corporation) [9,10].
2.2. Instruments and Methodology
In this study, for the purpose of monitoring in vitro the
changes of temperature values are based on the utiliza-
tion of two different types of thermocouples;
1) Digital Thermocouple
2) Thin wires Thermocouple
In all of experimental tests the tip is in the chamber with
dimension of 10 cm × 18 cm × 23 cm which is full of se-
rum solution (Sodium Chloride 0.9%). The size of cham-
ber is big enough so it acts as a thermal bath. Power of
system is on its pre-set value, 50% and intensity of waves
for this power are about 155 W/cm2 [10,11].
2.2.1. Digital Thermocouple
Digital thermocouple has a probe and can measure tem-
peratures near the phaco tip with sensitivity of 0.01℃. In
measurement with digital thermocouple, each experi-
mental test is repeated 5 times for every mode and the
averages of temperature changes in a period of 60 sec-
onds are plotted.
2.2.2. Thin Wires Thermocouple
Thin wires thermocouple which is made of two different
metal wires (Ni-NiCr) with sealing wax on them for
prevention of RF (radio frequency) waves [6]. With four
thin wires thermocouple temperatures are measured in
four different areas (Figure 3) near the tip indirectly by
the changes of voltage with sensitivity of 1 V and si-
multaneously are drawn by an X-Y recorder.
On the next stage temperature changes are measured
by thin wires thermocouple for the same tip in a period
of 60 seconds with the same initial conditions.
Because voltage changes are in the order of V, then
the numbers of peaks in a specific period of time are
greater so in these graphs four points are important for
us in comparison; starting point, maximum, minimum
Figure 2. Sina phacoemulsification system (Aali-Payam Co.).
Figure 3. Four different thin wires thermocouples monitor the
temperature changes of the tip.
and ending.
According to the position of operator’s foot on the
pedal of system, four positions are defined [7].
Position 0: Foot is off the pedal, no action.
Position 1: Initial depression of foot pedal. Fluid
flows from the bottle, no aspiration or emulsification.
Position 2: Pedal pushed to the detent. Aspiration
now accompanies irrigation.
Position 3: Pedal pressed to the next detent. With
phaco hand piece, emulsification now is added to irriga-
tion and aspiration.
Three operating modes were analyzed;
1) Linear mode, in this mode the power of ultrasound
waves are increased gradually from zero to the preset
power of the system and it directly depends on how far
down the pedal is pushed
2) Constant mode, in this mode the power of ultra-
sound emissions are equal to the preset power of system
immediately in the stages in which waves were used
3) Pulse mode, in this mode the ultrasonic stream is
not continuous but pulsed [8]
Phacoemulsifier tips come in a number of variations;

R. Tahvildari et al. / J. Biomedical Science and Engineering 3 (2010) 727-734 729
the three common ones are named for the angle of the
cutting area. They are 0 degree, the 15 degree, the 30
degree and the 45 degree.
The 45 degree tip has the longest bevel and therefore
the sharpest tip, so it cuts most easily. Because of the
large bevel of the aspiration port it occludes less easily.
The 30 degree tip has smaller bevel. Therefore the
port is smaller and occludes more easily so it is more
efficient for the aspiration.
Some surgeons like to vary the tip depending on the
density of the cataract: using a 45 degree tip for a hard
cataract and a 30 degree tip for softer cataracts and they
are the most popular so we have done all of the meas-
urements and comparisons for these two tips.
3. ANALYSIS OF RESULTS
In this study, for the purpose of monitoring in vitro the
temperature values around two tips with the angle of 30
and 45 degree, first the measurements are done by digital
thermocouple for different operating modes of phaco
system. On the next stage, same measurements are done
but with thin wires thermocouples.
3.1. 30 Degree Tip – Digital Thermocouple
Shown in Figure 4 and Table 1 are the temperature val-
ues monitored by digital thermocouple during system is
operating in linear and constant modes for the 30 Degree
tip. In linear mode maximum temperature increase is 0.5
℃ but in constant mode it is 0.47℃.
Shown in Figure 5 and Table 2, in pulse mode, when
the system is set to emit 10 pulses per second (pps), ma-
ximum temperature increase for linear – pulse mode
around the tip is 0.2℃ but for constant – pulse mode
this value is 0.23℃.
3.2. 30 Degree Tip – Thin Wires Thermocouples
In Table 3, the temperature values reached in linear and
constant modes around the tip which are measured by
thin wires thermocouples in four different areas around
the 30 Degree tip is shown.
Figure 6 are the temperature changes that are plotted
according to the voltage changes of each thermocouple
versus time in linear mode.
The maximum temperature increase in this mode for
thermocouples No.1 is 48, No.2 is 15, No.3 is 112 and
No.4 is 69 V.
Figure 7 are the temperature changes that are plotted
according to the voltage changes of each thermocouple
versus time in constant mode.
The maximum increase in this mode for thermocou-
ples No.1 is 56, No.2 is 19, No.3 is 97 and No.4 is 83
V.
In Table 4, the temperature values reached in linear –
21.5
21.6
21.7
21.8
21.9
22
22.1
22.2
22.3
22.4
0 10203040506070
Time (sec)
Temperature (C)
21.5
21.6
21.7
21.8
21.9
22
22.1
22.2
22.3
0 10203040506070
Time (sec)
Tem
p
erature
(
C
)
Figure 4. Linear mode – temperature values versus time [left];
constant mode – temperature values versus time [right].
Table 1. Temperature values for linear and constant modes
measured by digital thermocouple.
Average of
Endings
Average of
Minimums
Average of
Maximums
Average o
f
Starting
22.1 21.87 22.12 21.62
LINEAR
MODE
22.12 21.87 22.12 21.65
CONSTANT
MODE
Table 2. Temperature values for linear – pulse and constant –
pulse modes measured by digital thermocouple.
Average of
Endings
Average of
Minimums
Average of
Maximums
Average of
Starting
22.27 22.1 22.25 22.05
LINEAR
PULSE MODE
21.82 21.72 21.85 21.62
CONSTANT
PULSE MODE
pulse and constant – pulse modes around the tip which
are measured by thin wires thermocouples in four dif-
ferent areas around the tip is shown.

R. Tahvildari et al. / J. Biomedical Science and Engineering 3 (2010) 727-734 730
21.95
22
22.05
22.1
22.15
22.2
22.25
22.3
22.35
0 10203040506070
Time (sec)
Tem
p
erature
(
C
)
21.3
21.4
21.5
21.6
21.7
21.8
21.9
22
22.1
22.2
0 10203040506070
Time (sec)
Tem perature(C)
Figure 5. Linear-pulse mode (10 pps) – temperature values
versus time [left]; constant-pulse mode (10 pps) – temperature
values versus time [right].
Table 3. Temperature values for linear and constant modes
measured by thin wire thermocouples.
Starting Maximum Minimum Ending
THERMO
NO.1 -10 38 8 22
THERMO
NO.2 -3 12 -1 -2
THERMO
NO.3 -10 102 35 80
LINEAR
MODE
THERMO
NO.4 -4 65 41 50
THERMO
NO.1 -2 54 12 31
THERMO
NO.2 -2 17 1 2
THERMO
NO.3 3 100 59 89
CON-
STANT
MODE
THERMO
NO.4 1 84 21 67
Thermocouple No.1 Thermocouple No.2
Thermocouple No.3 Thermocouple No.4
Figure 6. Linear mode – voltage changes (V) versus time
(sec.) for each thermocouple.
Thermocouple No.1 Thermocouple No.2
Thermocouple No.3 Thermocouple No.4
Figure 7. Constant mode – voltage changes (V) versus time
(sec.) for each thermocouple
Table 4. Temperature values for linear – pulse and constant –
pulse modes measured by thin wire thermocouples.
StartingMaximum Minimum Ending
THERMO
NO.1 2 31 18 27
THERMO
NO.2 -8 8 1 2
THERMO
NO.3 -3 57 38 37
LINEAR
PULSE
MODE
THERMO
NO.4 -5 61 53 52
THERMO
NO.1 -11 21 8 10
THERMO
NO.2 -2 17 9 11
THERMO
NO.3 12 63 48 57
CONSTANT
PULSE
MODE
THERMO
NO.4 6 90 78 9

R. Tahvildari et al. / J. Biomedical Science and Engineering 3 (2010) 727-734 731
Figure 8 are the temperature changes that are plotted
according to the voltage changes of each thermocouple
versus time in linear – pulse mode when the system is
set to emit 10 pulses per second (10 pps). The maximum
increase in this mode for thermocouples No.1 is 29, No.2
is 16, No.3 is 60 and No.4 is 66 V.
Figure 9 are the temperature changes that are plotted
according to the voltage changes of each thermocouple
versus time in constant – pulse mode when again the
system is set to emit 10 pulses per second (10 pps).
The maximum increase in this mode for thermocou-
ples No.1 is 32, No.2 is 19, No.3 is 51 and No.4 is 84
V.
3.3. 45 Degree Tip – Digital Thermocouple
Shown in Figure 10 and Table 5 are the temperature
value monitored by digital thermocouple during the sys-
tem is operating in linear and constant modes for the 45
Degree tip.
In linear mode maximum increase is 0.72℃ but in
Thermocouple No.1 Thermocouple No.2
Thermocouple No.3 Thermocouple No.4
Figure 8. Linear – pulse mode (10 pps) – voltage changes (V)
versus time (sec.) for each thermocouple.
Thermocouple No.1 Thermocouple No.2
Thermocouple No.3 Thermocouple No.4
Figure 9. Constant – pulse mode (10 pps) – voltage changes
(V) versus time (sec.) for each thermocouple.
constant mode it is 0.67℃.
Shown in Figure 11 and Table 6, in pulse mode, when
the system is set to emit 10 pulses per second (10 pps),
maximum increase for linear – pulse mode around the
tip is 0.17℃ but for constant – pulse mode this value is
0.13℃.
3.4. 45 Degree Tip – Thin Wires Thermocouples
In Table 7, the temperature values reached in linear and
constant modes around the tip which are measured by
thin wires thermocouples in four different areas around
the tip is shown.
Figure 12 are the temperature changes that are plotted
according to the voltage changes of each thermocouple
20.2
20.3
20.4
20.5
20.6
20.7
20.8
20.9
21
21.1
21.2
21.3
0 10203040506070
Time (sec)
Temperature
(
C
)
20.2
20.3
20.4
20.5
20.6
20.7
20.8
20.9
21
21.1
21.2
21.3
0 10203040506070
Time (sec)
Tem
p
erature
(
C
)
Figure 10. Linear mode – temperature values versus time [left];
constant mode – temperature values versus time [right].
Table 5. Temperature values for linear and constant modes
measured by digital thermocouple.
Average of
Endings
Average of
Minimums
Average of
Maximums
Average of
Starting
20.97 20.92 21.07 20.35
LINEAR
MODE
21.12 20.85 21.02 20.35
CONSTANT
MODE

R. Tahvildari et al. / J. Biomedical Science and Engineering 3 (2010) 727-734 732
21.35
21.4
21.45
21.5
21.55
21.6
21.65
21.7
21.75
0 10203040506070
Time (sec)
Tem
p
erature
(
C
)
20.45
20.5
20.55
20.6
20.65
20.7
20.75
20.8
20.85
0 10203040506070
Time (sec)
Tem
p
erature
(
C
)
Figure 11. Linear -pulse mode (10 pps) – temperature values
versus time [left]; constant -pulse mode (10pps) – temperature
values versus time [right].
Table 6. Temperature values for linear – pulse and constant –
pulse modes measured by digital thermocouple.
Average of
Endings
Average of
Minimums
Average of
Maximums
Average of
Starting
21.62 22.55 21.57 21.40
LINEAR
PULSE MODE
20.72 20.65 20.70 20.57
CONSTANT
PULSE MODE
versus time in linear mode.
The maximum increase in this mode for thermocou-
ples No.1 is 40, No.2 is 32, No.3 is 47 and No.4 is 13
V.
Figure 13 are the temperature changes that are plotted
according to the voltage changes of each thermocouple
versus time in constant mode.
The maximum increase in this mode for thermocou-
ples No.1 is 9, No.2 is 19, No.3 is 64 and No.4 is 67 V.
In Table 8, the temperature values reached in linear –
pulse and constant – pulse modes around the tip which
are measured by thin wires thermocouples in four dif-
ferent areas around the tip is shown.
Table 7. Temperature values for linear and constant modes
measured by thin wire thermocouples.
StartingMaximum MinimumEnding
THERMO
NO.1 0 40 -2 9
THERMO
NO.2 -9 23 7 18
THERMO
NO.3 -7 40 0 8
LINEAR
MODE
THERMO
NO.4 -7 6 0 2
THERMO
NO.1 -5 4 -10 2
THERMO
NO.2 -8 11 -2 2
THERMO
NO.3 -14 50 10 15
CONSTANT
MODE
THERMO
NO.4 -5 62 32 56
Thermocouple No.1 Thermocouple No.2
Thermocouple No.3 Thermocouple No.4
Figure 12. Linear mode – voltage changes (V) versus time
(sec.) for each thermocouple.
Thermocouple No.1 Thermocouple No.2
Thermocouple No.3 Thermocouple No.4
Figure 13. Constant mode – voltage changes (V) versus time
(sec.) for each thermocouple.

R. Tahvildari et al. / J. Biomedical Science and Engineering 3 (2010) 727-734 733
Table 8. Temperature values for linear – pulse and constant –
pulse modes measured by thin wire thermocouples.
Starting Maximum Minimum Ending
THERMO
NO.1 0 12 -4 6
THERMO
NO.2 0 26 16 23
THERMO
NO.3 -2 12 -1 0
LINEAR
PULSE
MODE
THERMO
NO.4 4 58 33 54
THERMO
NO.1 -12 4 -8 2
THERMO
NO.2 6 30 8 21
THERMO
NO.3 -5 18 -7 -3
CONSTANT
PULSE
MODE
THERMO
NO.4 9 40 16 33
Figure 14 are the temperature changes that are plotted
according to the voltage changes of each thermocouple
versus time in linear – pulse mode when the system is
set to emit 10 pulses per second (10 pps). The maximum
increase in this mode for thermocouples No.1 is 12, No.2
is 26, No.3 is 14 and No.4 is 54 V.
Figure 15 are the temperature changes that are plotted
according to the voltage changes of each thermocouple
versus time in constant – pulse mode when the system is
set to emit 10 pulses per second (10 pps).
The maximum increase in this mode for thermocou-
ples No.1 is 16, No.2 is 24, No.3 is 23 and No.4 is 31
V.
4. CONCLUSION
In this study thermocouples have been used as an in-
strument for measuring the temperature changes of dif-
ferent tips to monitor and compare three operating mode
of phacoemulsification system.
All in vitro measurements are done with the same ini-
tial conditions. In evaluating the maximum temperature
reach in each operating mode, it has been found that for
both tips temperature changes in pulse mode (linear –
pulse and constant – pulse) has fewer and lower peaks.
The main reason is the periods of short time between
each pulsed wave allow the tip to get cool between two
successive emissions. Moreover, in these modes, the
system produces a lower thermal increase with respect to
the linear and constant modes.
It is strongly recommend that in cataract surgery with
Sina phaco system only linear – pulse and constant –
Thermocouple No.1 Thermocouple No.2
Thermocouple No.3 Thermocouple No.4
Figure 14. Linear – pulse mode (10 pps) – voltage changes
(V) versus time (sec.) for each thermocouple.
Thermocouple No.1 Thermocouple No.2
Thermocouple No.3 Thermocouple No.4
Figure 15. Constant – pulse mode (10 pps) – voltage changes
(V) versus Time (sec.) for each thermocouple.
pulse modes should be used, so to reduce any possible
surgical complications caused by the excessive release of
heat.
At the end it should be mentioned that although all the
experimental tests were performed in vitro and thermal
increasing of tip during surgical operation is higher than
these data, the results suggest this modern procedure can
be performed at a safe temperature with the knowledge-
able selection of surgeon-controlled parameters.
5. ACKNOWLEDGEMENTS
This research based on a collaboration research between Applied
Physics Center at Sharif University of Technology and an Iranian
medical engineering company (Aali-Payam Corporation).
We would like to thank Dr. M. Hashemi, Department of Ophthal-
mology at Iran University of Medical Sciences, for his guidance, help-
ful comments and support throughout this research.
Special thanks to all the members of Aali-Payam Co. for giving us
the opportunity to do this research on Sina phacoemulsification system

R. Tahvildari et al. / J. Biomedical Science and Engineering 3 (2010) 727-734 734
which is one of their products. We also thank the anonymous paper
reviewers for providing insightful comments.
REFERENCES
[1] Bond, L.J., Flake, M.D. and Tucker, B.J. (2003) Physics
of phacoemulsification. World Conference on Ultrasound,
Paris .
[2] Packer, M., Fishkind, W.J., Howard Fine, I. and Hoffman,
R.S. (2005) The physics of phaco: A review. Journal of
Cataract & Refractive Surgery, 31(2), 424-431.
[3] Corvi, A., Innocenti, B. and Mencucci, R., (2006) Ther-
mography used for analysis and comparison of different
cataract surgery procedures based on phacoemulsifica-
tion. Physiological Measurements, 27(4), 371-384.
[4] Yow, L. and Basti, S. (1997) Physical and mechanical
principles of phacoemulsification and their cilinical rele-
vance. Indian Journal of Ophthalmology, 45(4), 241-249.
[5] Osher, R.H. and Injev, V.P. (2006) Thermal study of bare
tips with various system parameters and incision. Journal
of Cataract & Refractive Surgery, 32(5), 867-872.
[6] Jones, L.D. and Chin, A.F. (1991) Electronic instruments
and measurements, Prentice-Hall, New Jersey, 300-303.
[7] Maloney, W.F., Grindle, L. and Fallbrook (1988) Text-
book of phacoemulsification. Lasenda Publishers, Cali-
fornia.
[8] Aali-Payam Co., (2006) Instruction manual of phaco
system. Sina Model, Tehran, 23-24.
[9] Ernest, P., Rhem, M., McDermott, M. and Lavery, K.
(2001) Phacoemulsification conditions resulting in ther-
mal wound injury,” Journal of Cataract & Refractive
Surgery, 27(11), 1829-1839.
[10] Tahvildari, R., Fattahi, H. and Amjadi, A. (2008) An in-
vitro Measurement of Temperature Changes in Phacoe-
mulsification System during Different modes. Proceed-
ings of the 2nd International Conference on Bioinforma-
tics and Biomedical Engineering, Shanghai, 1569-1574.
[11] Tahvildari, R., Fattahi, H. and Amjadi, A. (2007) Ther-
mal damage invesigation on Cataract surgery by Ultra-
sound waves. Proceedings of the 15th Annual Physics
Conference of Iran, Yasuj, 433-436.