Ophthalmology, Phacodynamics in phacoemulsification

2. Phacodynamic
Microscope
and pedal
Phaco Probe

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4. • Study of the fundamental principles of
inflow rates, outflow rates,
vacuum, phaco power modulation
• along with microsurgical maneuvers with
different types and grade of cataract

5. BASIC
TERMINOLOGY
• The initial process to make sure
that the microsurgical system is
optimum for the operation
• to remove air bubbles and check
leakage of the system.
• Air bubbles are removed by
infusing BSS to the system. This is
because air bubbles in the system
can expand under vacuum and
thus reducing pump efficacy.
Priming

6. BASIC
TERMINOLOGY
• Term used to describe the balance of inflow and
outflow fluid during phaco.
Fluidics
• Fluid that comes from irrigation bottle (BSS)
• Irrigation bottle > plastic tube > phaco needle >
anterior chamber
• Can be based on gravity or forced infusion pumps
Inflow
• Fluid that leaves the anterior chamber
• Either through aspiration flow or via wound leak
Outflow

7. BASIC
TERMINOLOGY
• The fluid flow leaving the eye through the
phaco tip during surgery
• Whenever either a venturi or peristaltic
aspiration system is running with the phaco
tip unoccluded, both perform aspiration
Aspiration
• Volume of fluid flowing through the tubing
at any given time.
• Measured in cc/min
• Increasing the flow rate improves the
attraction of particulate material to phaco
tip and increase the speed of events
Aspiration flow rate

8. BASIC
TERMINOLOGY
• Part of the phaco machine that
moves fluid through the
aspiration tubing
• Types are
• Flow pumps (Peristaltic)
• Vacuum pumps (Venturi)
• Hybrid pumps (Combination of
both)
Pump

11. • It controls the outflow of fluid through movement
of series of rollers over flexible tubing.
• The compression of tubing moves fluid through
the tube and creates a vacuum.
• Vacuum is controlled by amount of time the rollers
run over the tubing when occluded. This holds the
material at the phaco tip
• Direct control of aspiration rate
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13. • It applies principle of Venturi effect
• The flow of liquid or compressed gas across an opening
creates vacuum proportional to the rate of flow
• Consists of rigid collection cassette which connects the
pump to the aspiration line tubing
• Rigid walls allow it to maintain a preset vacuum level
without collapse
• Direct control of vacuum level
• Flow rate varies according to aspiration port size, vacuum
level and degree of occlusion
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14. 14
No Occlusion Occlusion Break
Vacuum = Low
Flow = Preset +
tubing rebounds
(surge)
Vacuum = Vac limit (high)
Flow = 0
Occlusion
Vacuum = Low
Flow = Preset

15. 15
No Occlusion
Vacuum = Preset level
Flow = 0
Occlusion
Vacuum = Preset level
Flow = Preset level
Occlusion Break
Vacuum = Preset level
Flow = Preset level

17. BASIC
TERMINOLOGY
• Negative pressure measure in mmHg
• It determines holding power.
Vacuum
• Change in volume of tubing when
subjected to negative pressure
• High compliant tubing – tendency to
collapse on itself when subjected to
–ve pressure
• Low compliant tubing – do not have
tendency to collapse on –ve pressure
Compliance

18. BASIC
TERMINOLOGY
• Event that occur during phaco
when there is a sudden
withdrawal of fluid from anterior
chamber when occlusion breaks
Surge

20. BASIC
TERMINOLOGY
• How quickly material comes to the
phaco tip. Expressed in cc/min
Followability
• How well material is held at the tip
once occluded. Expressed in
mmHg.
Holdability

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24. • POSITION 1: IRRIGATION
• POSITION 2: IRRIGATION AND ASPIRATION
• POSITION 3: IRRIGATION + ASPIRATION + PHACO

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28. • Longitudinal (Jack hammer)
• This can cause repulsion of nuclear fragment
• Torsional
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• Cavitation
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• each burst of energy has the same power but the
interval between each burst increases as the foot pedal
is depressed.
• The longer the foot pedal is depressed, the shorter the
“off” period between each burst will be.
• As a result, at maximum foot pedal depression, the bursts
of energy will become continuous delivery of energy.
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30. Sculpt Chop Epinucleus​ I/A​
Vacuum​ 50mmHg 380mmHg​ 240mmHg​ 500mmHg​
Flow rate​ 27cc/min​ 36cc/min​ 30cc/min​ 35cc/min​
Bottle
Height​
75cm​ 100cm​ 90cm​ 90cm​
Power​ 30%​ 30%​ 25%​ -