History, machine, mechanisms and terminologies in phacoemulsification

1. PHACOEMULSIFICATION
PART -1
BY- PRIYANKA RAJ

2. INTRODUCTION
• Introduced by Dr. Charles Kelman in 1962,
phacoemulsification machines have undergone constant
improvement, ever increasing both their complexity and
safety.
• All phaco machines consist of a computer to generate
electrical signals and a transducer to turn these electronic
signals into mechanical energy.
• The energy thus produced is passed through a hollow needle
and is controlled within the eye to overcome the inertia of
the lens and emulsify it.
• Once turned into emulsate, fluidic systems remove the
emulsate, replacing it with balanced salt solution (BSS).

3. PHACOMACHINE
• The machine consists of the
• Console,
• Handpiece
• Foot pedal,

4. CONSOLE
• The console consists of a computer which
controls all the functions of the machine.
• The computer generates ultrasonic waveform
and sends it to the transducer in the form of
electronic signals.
• The setting for the various parameters, i.e.
power, vacuum and flow rate are fed in here.
• These settings represent the maximum level
of the parameter that will be achievable
• Settings for different types of cataract can
also be fed into the memory.

5. HANDPIECE
• There are two types of handpieces
• 1. Irrigation aspiration handpiece
• 2. Phaco handpiece

6. IRRIGATION-ASPIRATION (I-A)
HANDPIECE
• The I-A tip differs from the phaco tip in being
smooth and rounded with a single aspiration
port on the side of the tip and not at the end.
• The aspirating port at one side usually 0.75 mm
to 1.5 mm away from the tip.
• The opening can be in a diameter of 0.2, 0.3,
0.4, or 0.5 mm.
• The angulations of the I-A handpiece can be
straight, 45° bent, or has a 90° bend.

7. PHACO HANDPIECE
• The phaco handpiece contains the
piezoelectric crystal, which is in contact with
the tip.
• The tip is covered by a silicon sleeve.
• The infusion fluid flows between the tip and
the sleeve cooling the former.
• There are two openings on the sleeve for the
exit of this fluid, which should be kept
perpendicular to the tip bevel.
• There are two more connections: one each
for the irrigation tubing and for connecting
the aspiration system.

8. PIEZOELECTRIC TRANSDUCERS
• They are based on the reversal of the piezoelectric phenomenon.
• Certain crystals, on compression, produce electric current.
• In reverse, electric current causes the crystal to contract.
• The crystal is mounted on a piece of tubing of narrowing diameter eventually
ending with the attachment of the phaco needle.
• The decreasing diameter tube acts as an amplifier to generate adequate power
for emulsification.
• There may be 2–6 crystals, 6 giving more stroke length and more power.

9. PHACO TIP
• Titanium
• hollow with the distal opening
functioning as the aspiration port.
• The acoustic energy produced along
the ultrasonic handpiece is then
transmitted onto the phaco tip.
• Usual Frequency 40 KHz
• Usual Amplitude 3/1000 of an inch
• Diameter (19 G-0.9mm,20G-0.6mm)

10. • The angulation of the tips may vary from 0–
60°. Tips with 60°, 45°, 30°, 15° and 0°
angulation are available.
• The commonly used tips are 30° and 45° phaco
tips.
• More the angulation, the lesser the holding
power but the cutting power is more.
• e.g. 60° tip is a sharper tapered tip making
occlusion difficult. But is useful for grooving
hard cataracts.
• Entering into the anterior chamber is easy with
the 60° tip and progressively harder with a 15°
or a 0° tip.

11. FOOT PEDAL
• Foot pedal control is the most
important aspect of phaco.
• Though the foot pedal of each
machine may have a different
design, it essentially consists of main
central part and side kicks.
• The main part of the foot pedal
controls infusion, aspiration and
phaco power.

12. • The entire distance that the foot pedal
traverses is divided by 2 dentations into 3
excursions-
1. I (irrigation only),
2. IA (infusion and aspiration) and
3. IAP (infusion, aspiration and phaco).
• In the I excursion, the pinch valve opens and
irrigation is switched on.
• There is no gradient in this step and the
irrigation is either switched fully on or off.

13. • The function of this dentation is to dissociate
infusion from irrigation-aspiration.
• As foot is brought back from IA/IAP excursion,
stopping at this dentation will keep the
on preventing the collapse of anterior chamber.
• Many steps like nuclear rotation, manipulation of
nuclear fragments, epinuclear plate etc. require a
formed AC without any aspiration.
• From dentation 2 to full depression is the phaco
or the ‘IAP’ excursion.
• At IAP0 phaco energy delivered will be zero and
at IAPmax the energy will be maximum preset.
• The delivery of phaco energy is linear both in the
surgeon and the pulse mode.
• However, in panel or burst mode, as soon as
foot clears IAP0, maximum preset energy is
delivered.

14. FOOT GRADIENT
• Foot gradient is the excursion of foot
pedal in mm to produce unit power of
phaco energy.
• If the total foot excursion, from IAP0 to
IAPmax is 10 cm i.e. 100mm and the
maximum preset phaco energy is 100%,
then the foot gradient (FG) becomes:
• Decreasing the maximum preset power
on console increases the foot gradient
and hence the foot control.
• Therefore, phaco maximum should be
set at the minimum power which is
required for a particular step in that
grade of cataract.

15. SIDE KICK FUNCTIONS OF FOOT
PEDAL
• The most important sidekick function of foot pedal is reflux.
• On kicking the side switch, aspiration flow rate is inverted and the material
aspirated is expelled into the AC.
• Since it is not a continuous function, for further reflux, the switch needs to be
kicked again.
• Inadvertent aspiration of wrong tissue (iris, capsule) can be released by this
function especially by beginners.

16. PHACODYNAMICS
• The various functions of the phaco machine and their inter relationship is called
phacodynamics.
• The basic functions of the machine are two, which include
1. ultrasonic power for emulsification
2. irrigation-aspiration for safe suction of the emulsified material.
• Irrigation-aspiration system and the parameters on which it depends together
are called fluidics.

17. POWER
• Ability to destroy lens nucleus.
Depends on:
1. Amplitude
2. Frequency
3.Coupling force

18. AMPLITUDE
• Stroke length: penetration of the tip into
nuclear mass with each oscillation
• Most machines operate in the 2 to 4 mil
range. (1 mil = 25μ) Therefore, most phaco
needles travel a distance of 50 to 100 μs.
• The longer the stroke length, the greater the
generation of cavitation energy.
• Longer stroke lengths tend to generate extra
heat.
• Stroke length is determined by foot pedal
excursion in position 3 during linear control
of phaco.

19. FREQUENCY
• Determines how much of amplitude will be transformed productively
into penetration
• The frequency is variable from 29–60 kHz in different machines.
• Higher frequency ensures a better cutting action but more heat is
generated.
• However, in each machine, the frequency remains fixed and power is
varied by varying the stroke length

20. COUPLING FORCE
• This can be achieved by:
• Pressing against the nucleus
• Aspirating
• Pressing the nuclear fragment with the second instrument

21. MECHANISM OF EMULSIFICATION
• The actual mechanism of emulsification is a
combination of
• Jack-hammer and
• Cavitation phenomenon
• Acoustic waves
• The jackhammer effect is the physical
striking of the needle against the nucleus.
The Jack-hammer action requires that the
nucleus should be fixed as for the
bombarding action to be effective. This is
the action that is primarily used during
trenching.

22. CAVITATION
• The phaco needle, moving through a liquid
medium at ultrasonic speeds, gives rise to
intense zones of high and low pressure.
• Low pressure, created with backward movement
of the tip, pulls dissolved gases out of solution,
thus producing micro bubbles.
• Forward tip movement then creates an equally
intense zone of high pressure.
• This initiates compression of the micro bubbles
until they implode.

23. • At the moment of implosion, the
bubbles create a temperature of 7204˚C
degrees and a shock wave of 5,171,100
mbar.
• Of the micro bubbles created, 75%
implode, amassing to create a powerful
shock wave radiating from the phaco tip
in the direction of the bevel with
annular spread.
• The energy created by cavitation exists
for no more than 4 milliseconds and is
present only in the immediate vicinity of
the phaco tip and within its lumen.

24. • Additionally, cavitation is instrumental in clearing nuclear fragments within the
phaco needle, preventing repetitive needle clogging.
• The angle of the bevel of the phaco needle governs the direction of the
generation of the shock wave and micro bubbles.
• The disadvantage of this wave is that it may push nuclear pieces away if the hold is
not good and thus decrease the Jack-hammer effect.

25. • Phacoemulsification is most efficient when both the jackhammer effect and
cavitation energy are combined.
• To accomplish this, the bevel of the needle should be turned toward the nucleus
or nuclear fragment.
• This simple maneuver will cause the broad bevel of the needle to strike the
nucleus.
• In addition, the cavitation force is then concentrated into the nucleus rather than
away from it.
• Also, in this configuration, the vacuum force can be maximally exploited as
occlusion is encouraged.

26. TORTIONAL ULTRASOUND
• Produces a side-to-side motion of the phaco tip
• Reduces the repulsion of nuclear material from the phaco tip.

27. CONTROL & DELIVERY OF POWER
• There are various modes
1. Surgeon/linear mode
2. Panel mode
3. Pulse mode
4. Burst mode

28. SURGEON/LINEAR MODE
• The power delivery varies from 0 to the maximum that one sets on the panel, by
varying the foot pedal in phaco mode.
• At pedal position 2, i.e. at the start of phaco mode (P0) the power will be 0 and
at full depression (Pmax) power will be the maximum that has been pre-set.
• Thus the excursion of the foot in phaco mode will determine the amount of
power being delivered.

29. PANEL MODE
• As soon as surgeon depress the foot pedal into the phaco mode (P0), he will
immediately reach the maximum power that has been set on the panel.
• Here, there is no variation and full power is delivered.
• The only probable indication for the use of panel mode is in a very hard cataract
where the nucleus is uniformly hard requiring more or less uniformly high power
for emulsification.

30. PULSE MODE
• In pulse mode each pulse of energy is
followed by a gap of equal duration.
• For effective power delivery, the nuclear
fragment has to be held, so the interval
between the pulses of phaco allow the
vacuum to build up and thus a good
hold is developed.
• Pulse mode is a variant of linear phaco
mode where the frequency of the pulses
is fixed and the phaco energy delivered
in each pulse will depend on the amount
the pedal is pressed.
• Most machines have from 0–12 pulses.
• The use of the pulse mode in phaco
aspiration almost halves the power use,
as the vacuum build up between the
pulses ensures efficient emulsification and
aspiration.

31. • Newer machines have softwares
which can have pulses in hundreds
and thousands, called the
hyperpulse mode.

32. BURST MODE
• Burst mode is where maximum power is
delivered at intervals which vary with the
amount you depress the foot pedal.
• Burst mode is a variant of panel mode
where the energy is fixed and the
frequency of phaco bursts will increase
with increasing depression of the foot
pedal in phaco mode.
• At P0 there will be one burst per second
and at full depression (Pmax) the power
delivery is continuous.
• The duration of the burst can be selected
and is usually 100 msec.

33. • Maximum phaco power
• Maximum obtainable ultrasonic energy when foot pedal control is fully
• Actual phaco power
• Power actually delivered at a given time proportional to foot pedal position.
• Effective phaco time
• Total phaco time at 100% phaco power.
• Less EPT: Less energy delivered to the eye thus reducing side effects

34. THANK YOU
To be contd.. In part 2