Phacomachine and its dynamics

1. Sujay Chauhan

2. Charles Kelman - visit to the dentist - ultrasonic device being
used to remove plaque and debris
Concept took almost two decades to make itself accepted

3. CAVITRON - KELMAN PHACOEMULSIFIER MARK I
- the original phaco machine
Kelman
Anterior chamber phacoemulsification
Sinskey (1970)
Posterior chamber phacoemulsification

4. Console
Handpiece
Foot pedal

5. Controls all the functions of machine:
 Phaco power delivery
 Irrigation and aspiration
Manipulation of parameters - power, vacuum, flow rate, etc.

6.  Phaco handpiece
 Irrigation - Aspiration (I & A) handpiece
PHACO HANDPIECE
Functions-
 Power delivery
 Irrigation
 Aspiration

7. PHACO POWER
Piezoelectric crystals in handpiece convert electrical energy
into mechanical vibrations - transmitted to phaco tip

8.  Hollow titanium needle
 Silicone sleeve - 2 ports, 180° apart
Types-
• Standard tip • Aspiration bypass system (ABS) tip
• Kelman tip • Micro flow tip
• Micro tip • Cobra tip
• Mackool tip • Diaphragm tip
• Flared tip • Turbosonics tip

9.  Straight shaft
 19 G
 Outer diameter = 1.1 mm
 Inner diameter = 0.9 mm
Tip can be bevelled at various angles-
Angle Cutting
power
Holding
power
Key point
0° * ***** Phaco chop
15° ** ****
30° *** *** Beginners
45° **** ** Sculpting
60° ***** * Sparingly used now

10.  Bent distal end - adds a non-axial vibration to the primary
longitudinal vibration - elliptical motion at the cutting tip -
increases total cavitation at the tip
 More effective in cutting hard nuclei
 Downward curve - lesser stress on the wound

11.  Straight shaft
 21G
 Outer diameter = 0.8 mm
 Inner diameter = 0.6 mm
Advantages-
 Needs smaller incision
 Precise cutting
 Enhanced surge protection because of smaller internal lumen

12.  Thin polyamide insulation tubing separates metallic shaft of
the tip from infusion sleeve
 Reduces heat transmission

13.  Proximal part- Internal diameter = 0.6 mm (20 G)
 Distal end- Inner diameter = 0.9 mm (19 G)
Outer diameter = 1.1 mm
 Better holding power when occluded
 Smaller diameter of proximal shaft - fluidic resistance
 Bigger diameter of distal end - more volume of nuclear material
engaged and aspirated per unit time of ultrasound power
application

14.  0.18 mm diameter hole at distal end
 Continuous outflow throughout nucleus emulsification,
even during occlusion
Advantages-
 Cools down the phaco needle, incision site, and entire
anterior chamber by replacing the fluid continuously
 Less chances of surge

15. External longitudinal grooves, smaller inner diameter
Advantages-
 Continuous irrigation, even when silicone sleeve is compressed
against the needle by incision pressure
 Smaller inner diameter - fluidic benefit of surge resistance

16.  Increased width at distal extremity
 More tendency of getting heated up
Constriction of the internal lumen at
distal end - acts like a diaphragm -
less surge
Hydrodynamically tapered hub

17. CO-AXIAL IRRIGATION ASPIRATION HANDPIECE
 Smooth rounded tip, 2 ports for irrigation, 1 for aspiration
 Irrigation ports - placed most commonly 90° away from
aspirating port
 Size of aspiration port = 0.2 - 0.7 mm (most commonly used =
0.3 mm)
 Smaller port - better vacuum seal, prolonged aspiration time
 Tip - straight or angulated (45°-90°)

18. Aspiration handpiece
 Usually curved, rounded tip
 Port 1 mm away from the tip
Infusion/irrigation handpiece
 Straight or curved
 Port at the tip or away from the tip

19. 4 positions-
Position 0
Resting position
Position 1 (Irrigation mode)
No gradient. Irrigation is either switched fully on or off

20. Position 2 (Irrigation Aspiration mode)
Irrigation is fully on
Amount of aspiration keeps on increasing with excursion till the
full preset value is achieved
Position 3 (Irrigation Aspiration Phaco mode)
Irrigation is fully on
Aspiration is at the maximum preset
Phaco power keeps on increasing with excursion
FOOT GRADIENT
Excursion of foot pedal in mm to produce unit power of phaco

21. SIDE KICK MOVEMENT FUNCTIONS OF FOOT PEDAL
Foot pedal reflux control
Aspiration flow is inverted
Pushes back the engaged iris or capsule
Continuous infusion mode (CIM)
Infusion remains ‘on’ in all the four positions of foot pedal

22.  Fluidics
 Phaco power
 Surge

23. Components-
 Irrigation system
 Aspiration system

24. CONVENTIONAL PHACO
 80 - 85 cc fluid/minute
 Height of irrigation bottle:
 AC is maintained with no collapse in case of surge
 Safe IOP level - without stress on zonules and lens-iris
diaphragm
 11 mm Hg IOP / 15 cm (6”) bottle height above the eye
 Ideally kept at 3 ± 1 ft
(theoretical IOP = 66 mm Hg, however, since wound and side
port are leaking, a safe IOP is maintained)

25. MICRO-PHACO
 Aspiration occurs through phaco tip and irrigation through
an irrigating chopper
 40 - 45 cc of fluid/min - not enough, so need to increase
irrigation through irrigating chopper
Methods to increase irrigation through irrigating chopper
 Increase bottle height
 Atmospheric pressure pump
 AC maintainer
 Pressurised bottle (by injecting air)
 Mechanised pressure infusion
 Pressurised plastic bottle (using BP cuff)

26. Functions:
 Anterior chamber lavage (outflow) - governed by flow
rate
 Creation of hold for emulsification of nucleus -
controlled by vacuum

27. Aspiration flow rate (AFR)
Volume of fluid in ml/min removed from eye
 Determined by pump speed, compliance, venting and tubing
 High AFR - swifter removal of lens matter with less power
 Low AFR - when working near the capsule

28. Rise time (RT)
Time taken from occlusion of phaco tip to reach maximum
preset vacuum
 Venturi pump - RT is fast, linear and dependent on highest
preset vacuum
 Peristaltic pump - RT depends on AFR
 Inversely proportional to bore size of phaco tip

29. Central safe zone (CSZ) - central area within the
capsulorhexis margin
Peripheral unsafe zone (PUSZ) - capsular fornices and angle
of anterior chamber
Smaller CSZ Larger CSZ
Hypermetropia Myopes
Narrow pupil Zonular stress syndromes
Small capsulorrhexis Vitrectomized eyes

30.  Ability of the fluidic system to attract and hold nuclear or
cortical material on the distal end of hand-piece until the
material is evacuated by the vacuum forces
 Created by pressure gradient of the tip (positive pressure
due to infusion and negative pressure due to vacuum)
 Venturi pump is more efficient than peristaltic pump in
creating negative pressure, so followability is good

31. A. Zone of good followability - area around the phaco tip
B. Zone of poor followability - near angle of AC and capsular
fornices
C. Zone of no followability - area around main and sideport
incisions and near dome of cornea

32. Flow pumps
AFR and vacuum limit are set by surgeon
AFR is maintained while vacuum varies with fluidic
resistance (occlusion of tip) up to the maximum set limit
 Peristaltic pumps
 Scroll pumps
Vacuum pumps
Surgeon controls the vacuum
 Venturi pumps
 Diaphragmatic pumps
 Rotary vane pumps

33. Peristaltic pumps
 Series of rollers on rotating cylinder compresses a soft
silicon tube against rigid wall of the pump
 Peristaltic wave pushes column of liquid in direction of
rotation

34. Advantages
 Slow vacuum build up
 AFR and vacuum can be set independently
 Higher safety margin
Disadvantages (due to high compliance tubing)
 Surge
 Pump leakage

35. Scroll pump
Rigid, orbitally rotating pump element placed directly
within the fluidic circuit
e.g. Bausch and Lomb Millennium Concentrix
Advantages (due to less compliance tubing)
 Less surge
 Less pump leakage

36.  Preset vacuum level is instantaneously achieved
 AFR is governed by:
• Level of preset vacuum
• Aspiration port size
• Degree of occlusion of aspiration port
• Viscosity of aspiration fluid
 Rigid drainage cassette (does not collapse)
 Good followability
Disadvantage
Increased risk of posterior capsular rupture and iris trauma

37. Venturi pump
 Compressed gas (nitrogen or air) generates vacuum
 Vacuum regulated by varying the
size of opening by a valve
Diaphragmatic pump
 Vacuum generated by in and out movements of a flexible
diaphragm caused by a rod connected to rotating electric
motor
 Amount of vacuum created directly
proportional to the pump motor speed

38. Rotary vane pump
 Vacuum created by the motor driven movements of a rotor
containing freely sliding flat vanes, mounted eccentrically
in the pump housing
 Amount of vacuum created directly proportional to the
pump motor speed

39. PERISTALTIC VENTURI
 Vacuum rise time slow
 Flow rate & vacuum can
be dissociated
 Less followability
 Better for a beginner or a
slow surgeon
 Easily portable
 Vacuum rise time quick
 Flow rate & vacuum
cannot be dissociated
 More followability
 Better for a faster
surgeon
 Not easily portable

40. MECHANISM OF ACTION
 Direct impact (Jackhammer effect) - depends upon stroke
length and frequency of vibration
 Chatter - repulsion of nuclear fragments from the tip
 Cavitation - formation of gas bubbles from the fluid in
response to pressure changes at the phaco tip. Implosion of
these bubbles produce brief instances of intense heat and
pressure
 Acoustic wave effect - sonic wave propagation through the
fluid

41.  Continuous mode
 Pulse mode
 Burst mode
 HyperPulse mode

42.  Constant delivery of phaco power
 For sculpting deep grooves in the nucleus
Fixed panel control mode
 Power can be set from 0–100%
 Set level of power is delivered and there is no variation in
power when foot pedal is depressed
 Preferred in very hard cataracts

43. Surgeon/linear control mode
 Allows variable power delivery from ‘0’ to maximum
 Amount of phaco power delivered can be controlled by
varying the excursion of the foot pedal in position 3

44.  Linear power delivery but at fixed intervals
 Upto 20 pulses/second are delivered
Advantages
 Phaco-power delivery is reduced by 50%
 Stable anterior chamber is maintained
 Decreased chatter at the tip
 Allows more followability

45.  Maximum preset power is delivered with each burst, but
the interval between each burst decreases as the foot pedal
is depressed
 At the end of position 3 excursion, the power delivery
becomes continuous
Advantages
 Uses much less ultrasound energy than pulse mode
 Helpful for hard cataracts

46.  Linear power delivery with ‘off’ time more than ‘on’ time
 Up to 100 pps are delivered
Advantages
 Low energy delivered due to brief duration pulses
 Thermal protection against corneal burns
due to increased ‘off’ time (cold phaco)
 Increased followability
 Decreased chatter

47. Duty cycle =
 Continuous mode = 100%
 Pulse mode = 50%
 Burst mode < 50%
 HyperPulse mode < 50%
On time
On time + Off time

48. Occurs due to extra fluid aspiration when occluded phaco tip
with built up vacuum is suddenly dis-occluded
Effects of surge
 Anterior chamber collapse
 Damage to iris and cornea
 Posterior capsular rupture

49.  Compliance of tube
 High vacuum level
 High AFR
Critical limit
Upper limit of AFR at which AC remains stable for a fixed
bottle height and fluid leakage
At critical limit,
AFR + Wound leakage = Infusion

50.  Improvisation in the phaco machine
 Surgeon’s measures to control surge

51. Improvisation in the phaco machine
Reduce compliance
 Biocompliant tubing - more compliant tubing at point of
pump rollers and less compliant tubing between pump and
handpiece (Alcon Legacy)
 Sealed rigid cassettes with stiff polymer membrane (Fluid
Management System, Alcon Infiniti)
 Software control algorithms to compensate for leakage
(Advanced Flow System, Bausch and Lomb)
Increase inflow
 High infusion phaco sleeve (provides more inflow potential to
keep AC formed)
 Second irrigation bottle

52. Pressure transducer and logarithmically control of pump
Logarithmically decrease the pump speed as vacuum
approaches maximum preset
When pressure transducer senses an occlusion break, there is
delay in starting the pump by a second or so
Speed is increased again logarithmically rather than abruptly
Smaller diameter tubings and phaco tips
Micro-flow and proximal end of flared phaco tips
ABS tip

53. Venting

54. Fluid-venting is superior to air-venting - air is compressible,
increases compliance of tubing

55. Cruise control
 Disposable flow restrictor - attached between phaco
handpiece and aspiration tubing
 Internal diameter = 0.3 mm
 Placed behind a mesh filter that
traps emulsified nucleus to
prevent the flow restrictor from
getting clogged
 Allows use of higher flow rates
and vacuums

56. Differential AFR and vacuum settings before and after
occlusion
 Immediately after the occlusion breaks, the AFR and vacuum
are decreased for a short period to prevent the surge
 After the nuclear piece has been aspirated, the settings revert
back to higher values to allow a better grip of the next
nuclear piece

57. Surgeon’s measures to control surge
 More resistive phaco needle (Micro-flow or Flare tip)
 More resistive tubing set (Alcon Max Vac)
 Augment inflow by using high infusion sleeves (Alcon) or
anterior chamber maintainer (ACM)
 Proper wound construction
Leaky wound disturbs equilibrium of AC - even small
amount of fluid withdrawn on break of occlusion can cause
surge
Tight wound or long tunnel reduces inflow & disturbs
equilibrium of inflow vs. outflow - surge

58.  Increase bottle height
 Lower vacuum setting
 Decrease AFR
 Partial occlusion of tip with another nuclear fragment before
the occlusion breaks and the occluding piece is aspirated
 Good foot control
 Viscoelastic substances - decrease effective flow rate, as
viscous fluid increases resistance and does not flow out
easily

59. Surge in peristaltic pump
▼ Independent control of vacuum and AFR
▲ More compliant tubing

60. Surge in venturi pump
Machine off - walls of tubing in normal position
Foot pedal pressed to position 2 - maximum vacuum built
 Tip not occluded - some amount of collapse of tubing
 Tip occluded - increased collapse of tubing
 Occlusion breaks - tubing expands, but still remains
collapsed by some amount as negative pressure still persists
in the system
Thus, only a small amount of fluid is aspirated and AFR
remains below critical limit

61. NeoSonix technology
Rotational oscillations up to 2° at 120 Hz
Ozil torsional technology
Rotatory movements of phaco needle at 32 kHz and longitudinal
movements at 44 kHz

62. Dual linear pedal -
2 planes of pedal movement:
 Pitch (up and down)
 Yaw (side to side)
Advantage - Simultaneous & independent control of
parameters
 High vacuum, High ultrasound – initial impaling nucleus
 High vacuum, No ultrasound – gripping & centrally displacing
heminucleus
 Moderate vacuum, No ultrasound – horizontal chop
 Moderate vacuum, Moderate ultrasound – phacoaspiration of
chopped fragment

63. Custom control software (CCS)
 5 modes - continuous, pulse, single-burst, fixed-burst,
multiple-burst
 Pulse mode - up to 120 pps possible (conventionally up to
20 pps)
 Multiple burst - microburst (4 msec), duty cycle limit can
be set to prevent continuous power even at full depression
of the foot pedal

64. Sonic frequency: 40 - 400 Hz (standard ultrasonic frequency:
27 - 60 kHz). Less heat & tip does not produce cavitation effect
SuperVac tubing: high vacuum (up to 650 mm Hg)
Being coiled, it provides surge control
Continuous change in direction of flow increases resistance at
high flow rates such as upon clearance of occlusion of tip. Un-
occluded flow is not restricted
Auto-correlation mode - adjusts vacuum as a function of
power
Cruise control chamber

65. WhiteStar ICE (increased control and efficiency)
 Eliminates heat production
 Higher phaco energy in the initial part of pulse separates
nuclear material from the phaco tip and creates a ‘microvoid’
between occluded tip and nuclear material
 Microvoid allows fresh BSS to get between phaco tip and
nuclear material - accelerates cavitational emulsification

66. Digital ultrapulsing of ultrasound energy
 Allows surgeon to select a duty cycle that sensitively controls
delivery of phaco power
 Micropulsing reduces total expanded energy
WhiteStar CASE (chamber stabilization environment)
 Adjusts vacuum before occlusion break by reversing the
pump to actively step down vacuum
 Reacts in as little as 26 msec & significantly reduces anterior
chamber shallowing

67. Thank you !