PHACODYNAMICS
Phacoemulsification for Residents Unpad - Cicendo Eye Hospital 2020
Andrew M.H. Knoch, MD
Two Basic Elements of Phaco Dynamics
Ultrasound Power:
• emulsify the crystalline lens Fluidics:
• remove the emulsate via the aspiration port
• counteract the potential heat buildup and repulsive action of the phaco tip
• maintaining adequate depth and pressure in the anterior chamber
Phaco Machine
Consist of :
• Console
• Foot pedal
• Handpiece
Console
Control panel
Mainframe (Phaco driver)
Fluid management system
Hand piece Foot pedal
BSS Lift Rod
Console.
Phaco driver (Computer)
Handpiece
Electrical
energy Phaco tip
mechanical
energy cataract
Phaco cataract surgery requires the use of complex phaco machines
Foot Pedal
• Three major function, controlled with foot pedal :
• Irrigation
• Aspiration
• Fragmentation
Foot Pedal.
Foot pedal position 2 and 3 :
Linear / Fixed /
Surgeon Control Panel
Handpiece
Irrigation
Aspiration
Phaco tip
Phaco Handpiece
I/A Handpiece.
Main Phaco Parameter
Flow Rate
Vacuum
Power
Aspiration Flow Rate (cc/min)
• Primary force that attracts material to the phaco tip
• Determines how fast material is drawn to the tip = Followability
High Flow
Low Flow
Vacuum –Occlusion (mmHg)
Ultrasound Power = Stroke Length (%)
• Frequency (kHz) – fixed How OFTEN
• Stroke length (%) – variable How FAR
This length is generally 2 to 4 mils (50 – 100um）
Stoke length
Stroke Length
• The setting phaco power is the percentage of stroke length Such as :
The maximum stroke length = 100um
30%(phaco power) = 100um(stroke length ) X 30%
= 30um
The actual stroke length is determined by :
• phaco machine setting
• foot pedal excursion in position 3
Phaco Parameters
Aspiration Flow Rate
• cc/min
• Followability
Vacuum
• mmHg
• Holding Forces
Ultrasound Power
• %
• Emulsifying forces
Others
• Bottle height
• U/S Power Modulation
Bottle Height
Every 15cm (6 inches) bottle height above the eye
=
Approximately 11mmHg pressure is produced intraocularly
Surge
Surge
Surge
Surge
Bottle Height and Vacuum.
Vacuum Bottle Height
150 65
200 – 250 85
250 - 300 110
U/S Power Modulation
Continous
Pulse
Burst
Continuous mode
START FOOTSWITCH
POSITION 3
FINISH FOOTSWITCH
POSITION 3
The power(stoke length) is determined by foot pedal
Pulse mode
START FOOTSWITCH
POSITION 3
FINISH FOOTSWITCH
POSITION 3
The power is determined by foot pedal
Linear power
Pre-selected Duty Cycle (on-off time)
Burst mode
START FOOTSWITCH
POSITION 3
FINISH FOOTSWITCH
POSITION 3
The duration is determined by foot pedal
Variable duration(Duty Cycle) Fix power
Burst and Pulse
burst
pulse
Finish FP3 Start FP3
Finish FP3 Start FP3
Continous, Pulse, Burst ?
Sculpting : Linear, Continuous mode or pulse
mode
Chopping:
Burst mode then to have the vacuum on
fixed so that it will build
quickly
Quadrant removal:
Pulse mode
TAKE HOME MESSAGE
Understanding Phacodynamics :
• Allows surgeon to optimize machine settings
• Safely trouble shoot problems during surgery
THANK YOU
Phaco Setting
Bottle Height
• 30 cm = 1 feet = 22 mmHg
• 60 cm = 2 feet = 44 mmHg
• 90 cm = 3 feet = 66 mmHg Flow Rate
• Peristaltic : 20 - 30 cc/min optimum Vacuum
• + 10 times of Flow Rate
Phaco Setting
Power for Sculpting :
• Power = (grade of nucleus x 15) + 25
• Grade 1 = 15 + 25 = 40%
• Grade 2 = 30 + 25 = 55%
• Grade 3 = 45 + 25 = 70%
• Grade 4 = 60 + 25 = 85%
• Grade 5 = 75 + 25 = 100%
Power for Quadrant Removal
• 30% less than Sculpting
Two Types of Pump
Venturi Pump: Pressure Type – Active Control of Pressure, Passive Change of Flow
Peristaltic Pump: Flow type – Active Control of Flow, Passive Change of Pressure
Venturi vs Peristaltic
Vacuum –Rise Time
• The faster the flow rate, the shorter the vacuum rise time
• Aspiration flow rate decreased by half, the vacuum rise time is doubled
