Overview of Phaco

1
Overview of Phaco

• Dr. Anil Kulkarni, M.S.
• Miraj

2
Phacodynamics

• Common Terms
• USG power
• Irrigation
• Aspiration/ Flow
• Vacuum

3
ACOUSTIC VIBRATOR

• Two Types
• Magneto-restrictive-
• Piezoelectric electrical energy is used to
  reorient piezoelectric crystal which in turn is
  translated in to linear movement.

4
ULTRASONIC POWER

• Vibration of tip Energy release
• Jackhammer effect
• Cavitation
• when tip retreats fluid cannot follow,
• void created produce tiny bubbles
• Bubbles implode amongst themselves creating
  shock waves.
• Heat (By product)

5
ULTRASONIC POWER

• Phaco Power Power depends on Amplitude
  (stroke length) of phaco tip
• Continuous Power
• Pulse Power
• Burst Power

6
ULTRASONIC POWER

• Linear On pressing the foot pedal there is
  gradual rise of parameters from O to preset
  values with a linear relation to foot pedal
  control.
• Panel On pressing foot pedal, the parameters
  reach to the preset panel values.

7

ULTRASONIC POWER

• Constant Mode
• Power is delivered continuously.
• It can be linear or panel controlled.
• Pulse mode
• Phaco power is delivered at preset intervals.
• It can be varied.
• It gives relative intervals, where there is
  absence of tip movement.

8
ULTRASONIC POWER

• Effective Phaco time
• It is the total phaco time at 100 phaco power.
• It can be less than total foot pedal time.
• Less EPT indicates less energy delivered to the
  eye.

9
Irrigation

• Gravity driven
• IOP gt 10 mm Hg
• wound leak reduces pressure spikes
• Bottle height 30-75 cm
• double irrigation for high vacuum

10
ASPIRATION SYSTEM

• Aspiration Evacuation of fluid through a closed
  system.
• Flow Rate Quantity of fluid pulled from the eye
  per minute through the instrument tip
• Measured in CC/Min.

11
PERISTALTIC PUMP

• Principle A pressure differential is created by
  compression of the aspiration tubing in a
  rotating motion.
• Aspiration tube passes over the knobs.
• When the drum rotates aspiration tube is
  successively compressed by the knobs over the
  drum to produce vacuum in the tubing.

12
VENTURI PUMP

• This uses compressed gas to create inverse
  pressure.
• Vacuum generated is related to gas flow which is
  regulated by a valve.
• The vacuum build up is almost instantaneous on
  pressing the foot pedal.

13
Surge

• Sudden increase in outflow uncompensated A/C
  collapse
• High IOP and negative pressure in aspiration
  tubing

14
Surge Prevention

• Decrease vacuum
• decrease flow rate
• non compliant tubes
• tighter wound
• raise bottle height
• microprocessor
• venting

15
Venting

• Safety mechanism to limit the vacuum to
  predetermined maximum level
• bleeding air or fluid in aspiration line.
• Balance IOP and negative pressure in aspiration
  line

16
Rise time
17
SUPERIOR INCISION

• BETWEEN 11 1 OCLOCK
• Advantages
• a. Maximum protection against infection
• b. Easy for beginners
• Disadvantages
• a. Difficult to construct work in deep
  seated eyes
• b. Poor visibility - corneal folds
• c. Less Red Glow
• d. Difficult in cases of filtering surgery
• e. Maximum ATR

18
TEMPORAL INCISION

• BETWEEN 8 10 O Clock.
• Advantages
• a. Easy to make/manipulate in deep seated
  eyes
• b. Good tissue visibility
• c. Maximum red glow
• d. All types of cases
• e. Less foreign body sensation
• Disadvantages
• a. More chances of infection
• b. Sitting position difficult.

19
CLEAR CORNEAL INCISION

• SIMPLE FAST
• Diamond Blades
• Single plane incision - single blade
• (No groove/No cautery/ No scleral tunnel)
• Easy for topical anesthesia
• DISADVANTAGES
• a. More chances of Infection
• b. More endothelial damage
• c. Increased astigmatism (if gt5 mm)

20
ASTIGMATIC CONSIDERATIONS

• Incision funnel Bonded by two curved lines.
  Incisions made with in the funnel
• Curvilinear incision - Maximum ATR
• Straight line incision - Less ATR
• Frown /Cheveron incision - Least ATR
• SITE OF INCISION
• Superior incision - More ATR
• Supero-temporal Incision - Moderate ATR
• Temporal Incision - Least ATR

21
(No Transcript)
22
Methods To Enlarge Pupil

• Sphincter sparing
• 1. Synechiolysis
• Old uveitis,
• Prior surgery,
• prolonged miotics
• 2. Membranectomy
• 3. Visco elastic Cohesive
• eg. Na,Hyaluronate

23
Methods To Enlarge Pupil

• B) Involving the sphincter
• Pupil Stretching
• By two instruments
• By Prongs

24
Methods To Enlarge Pupil

• Mini sphincterotomies
• Grieshaber Iris hooks
• Pupil ring expanders
• Iridotomy

25

• Gradual Enlargement of the Pupil is preferred
  over rapid, sudden tugging.
• Stretching always performed under visco elastic
• Intra cameral Lidocaine may be necessary
• Aim for adequate pupil (Not very large)

26
Undesirable effects

• Large sphincter tears
• Atonic pupil, photophobia
• Deformed pupil / Aesthetic change
• Iris haematoma

• Iris damage
• Mechanical,
• -- Thermal
• Cost involvement
• Post operative inflammation

27
Capsulorhexis

• Posterior Zonular Fibres are inserted 1 to 1.5
  mm. and Anterior Zonular Fibres about 2 mm. From
  Equator.
• Central 6 mm. is Zonule free area of the anterior
  Capsule.
• Krag by computer simulation showed that C.C.C.
  diameter needs only to be 1/2 to 2/3 diameter of
  IOL Optic diameter.

28

• Anterior chamber maintained
• 
  Visco elastic
• Air
• A/C maintainer.
• Bent needle of 26 No.
• Or Forceps can be used.
• Shearing
• Ripping
• While tearing, always catch the cutting edge.

29
CCC Advantages

• In the Bag Phaco emulsification is possible.
• Centering of IOL is possible.
• In case of PCR, IOL can be implanted over the
  capsular rim.
• Chances of posterior synechiae are reduced.

30
Complications

• Shrinkage of anterior capsular opening.
• Capsular bag hyperdistension.
• Epithelial cell hyperproliferation on the
  posterior capsule.

31
Hydrodissection

• Through side port
• No escape of fluid hence post capsular rupture
  
• (Always use main incision)
• Large Volume Fluid Trapped
• to avoid ½ ml. at a time, at 2-3 places,
  after lifting the anterior capsule

32
Nucleus Management

• Soft cataract/ posterior subcapsular cataract
• SPRING Technique
• Hard Cataract Cracking operations.
• 1. Divide Conquer
• 2. Stop Chop
• 3. Quick Chop.

33
SPRING TECHNIQUE

• Sequential Pulsed Removal of Inner Nuclear
  Girdle.
• Central Sculpting - Broad Deep
• Relaxing Nucleotomies 7.30, 4.30, Center.
• Aspiration of the collapsed wings.
• Spring with crack hybrid technique.

34
SPRING
35
DIVIDE CONQUER

• 4 Basic steps
• 1. Sculpting to a very thin posterior nuclear
  Plate.
• 2. Fracturing nuclear rim and posterior plate.
• 3. Fracturing again to break wedge shaped
  Section.
• 4. Rotating the nucleus, further fracturing
  followed by emulsification.

36
TRENCH, DIVIDE CONQUER

• Trench should be small, central vertical to
  leave enough firm nucleus for applying force of
  two instruments.
• More nuclear density - fuller
  length of trenching.
• Crack starts at the posterior pole
• and then extends to 6 12 oclock.
• Hemisections are then further divided.

37
CRATER, DIVIDE CONQUER

• Deep Central Sculpting to produce large crater
  leaving dense peripheral rim, for fracturing.
• Harder the nucleus
• smaller the wedge shaped sections.
• All sections are left in the bag
• To keep it distended
• To keep ultrasonic turbulence in bag.

38
Nagahara Chop

• Advantage Least phaco time.
• Disadvantage
• Pieces rejoin and prevent their removal
• Threat to the integrity of anterior capsule by
  chopper

39
Stop chop

• Kochs modification
• Trench sculpted nucleus is halved,
• then stop and start chop.

40
PHACO QUICK CHOP (PFIFER)

• Main difference is placement of chopper.
• It is placed on top of the buried phaco tip near
  centre of lens- away from anterior capsular rim.

41
PHACO QUICK CHOP (PFIFER)

• near vertical chopping.
• Chopper pushed down, phaco tip moves up and then
  both are laterally separated.
• Prepare all fragments before emulsifying to
  enable endo capsular phaco.
• 2mm exposure of phaco tip.

42
Coaxial MICS

• Use of micro tip
• Nano sleeves
• Incision 2 2.2 mm
• No change in surgeons technique
• IOLs available for insertion
• High vacuum and phaco aspiration possible

43
P.C. Rent (INTRA-OP FACTORS)

• Peripheral escape of rhexis
• forceful hydrodissection
• high vacuum and high power settings
• one handed technique-chasing the fragments
• sculpting too deep / too peripheral

44
POSTERIOR CAPSULAR RENT
signs

• Sudden deepening of the AC.
• New found difficulty in emulsifying the nucleus
• mydriasis / pupil distortion
• Visible vitreous in AC!!..
• STOP!! EVALUATEPLAN..!!

45
RENT CONTROL ACTS..!!! The 10 commandments..

• FREEZE movements,reduce bottle height
• inject visco from side port
• stop irrigation
• press reflux
• withdraw phaco tip from AC
• Assess damage-site , extent of rent.

46
Rent control acts..!! Contd..

• 6. Mechanized bimanual vitrectomy
• 7. Removal of residual nuclear fragments
• 8. Dry cortex aspiration
• 9. Re-assess capsular support
• and insert IOL PC / AC
• 10.Secure wound closure
• Post op care-antibiotics, steroids, NSAIDs