Eye Ctaract

7/27/2019 Eye Ctaract

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Overview of Phaco

Dr. Anil Kulkarni, M.S.

Miraj


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Phacodynamics

Common Terms

USG power

Irrigation

Aspiration/ Flow

Vacuum


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ACOUSTIC VIBRATOR

Two Types

Magneto-restrictive-

Piezoelectricelectrical energy is used to

reorient piezoelectric crystal which in turnis translated in to linear movement.


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ULTRASONIC POWER

Vibration of tipEnergy release

Jackhammer effect

Cavitation :

when tip retreats fluid cannot follow,

void created produce tiny bubbles

Bubbles implode amongst themselves creatingshock waves.

Heat (By product)


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ULTRASONIC POWER

Phaco Power : Power depends onAmplitude (stroke length) of phaco tip

Continuous Power

Pulse Power

Burst Power


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ULTRASONIC POWER

LinearOn pressing the foot pedal there is gradual

rise of parameters from O to preset values with a

linear relation to foot pedal control.

PanelOn pressing foot pedal, the parameters

reach to the preset panel values.


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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 oftip movement.

ULTRASONIC POWER


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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.


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Irrigation

Gravity driven

IOP > 10 mm Hg

wound leak reducespressure spikes

Bottle height 30-75 cm

double irrigation for

high vacuum


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ASPIRATION SYSTEM

AspirationEvacuation of fluid through a closedsystem.

Flow RateQuantity of fluid pulled from the eye perminute through the instrument tip

Measured in CC/Min.


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PERISTALTIC PUMP

PrincipleA pressure differential is created bycompression of the aspiration tubing in a rotatingmotion.

Aspiration tube passes over the knobs.

When the drum rotates aspiration tube is successivelycompressed by the knobs over the drum to producevacuum in the tubing.


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VENTURI PUMP

This uses compressed gas

to create inverse pressure.

Vacuum generated isrelated to gas flow which is

regulated by a valve.

The vacuum build up isalmost instantaneous on

pressing the foot pedal.


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Surge

Sudden increase in

outflow

uncompensated =

A/C collapse

High IOP and

negative pressure in

aspiration tubing


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Surge Prevention Decrease vacuum

decrease flow rate

non compliant tubes

tighter wound

raise bottle height

microprocessor

venting


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Venting

Safety mechanism to limitthe vacuum topredetermined maximumlevel

bleeding air or fluid inaspiration line.

Balance IOP and negativepressure in aspiration line


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Rise time


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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


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TEMPORAL INCISION

BETWEEN 8 & 10 O Clock.

Advantages :

a. Easy to make/manipulate in deep seated eyes

b. Good tissue visibilityc. Maximum red glow

d. All types of cases

e. Less foreign body sensation

Disadvantages :

a. More chances of infection

b. Sitting position difficult.


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CLEAR CORNEAL INCISION

SIMPLE & FAST

Diamond Blades

Single plane incision - single blade

(No groove/No cautery/ No scleraltunnel)

Easy for topical anesthesia

DISADVANTAGES :

a. More chances of Infection

b. More endothelial damage

c. Increased astigmatism (if >5 mm)


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ASTIGMATIC CONSIDERATIONS

Incision funnel : Bonded by two curved lines.

Incisions made with in the funnel :

Curvi l inear incis ion - Maximum ATR

Straight l ine incis ion - Less ATRFrown /Cheveron incis ion - Least ATR

SITE OF INCISION

Superior incision - More ATR

Supero-temporal Incision - Moderate ATR

Temporal Incision - Least ATR


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Methods To Enlarge Pupil

A) Sphincter sparing

1. Synechiolysis

Old uveitis,

Prior surgery,prolonged miotics

2. Membranectomy

3. Visco elasticCohesive

eg. Na,Hyaluronate


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B) Involving the sphincter

1. Pupil Stretching

: By two instruments

: By Prongs


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2. Mini sphincterotomies

3. Grieshaber Iris hooks

4. Pupil ring expanders

5. Iridotomy


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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)


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Undesirable effects

Large sphincter tears

Atonic pupil,

photophobia

Deformed pupil /

Aesthetic change

Iris haematoma

Iris damage

Mechanical,

-- Thermal

Cost involvement

Post operativeinflammation


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Posterior Zonular Fibres are inserted 1 to 1.5mm. 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.

Capsulorhexis


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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 thecutting edge.


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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.


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Shrinkage of anterior capsular opening.

Capsular bag hyperdistension.

Epithelial cell hyperproliferation on theposterior capsule.

Complications


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Hydrodissection

Through side port :

No escape of fluid & hence

post capsular rupture(Always use main incision)

Large Volume Fluid Trapped[ to avoid ml. at a time,at 2-3 places, after lifting theanterior capsule]


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Soft cataract/ posterior subcapsular cataract

SPRING Technique

Hard Cataract : Cracking operations.

1. Divide & Conquer

2. Stop & Chop

3. Quick Chop.

Nucleus Management


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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.


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SPRING


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CRATER, DIVIDE & CONQUER

Deep Central Sculpting to produce

large crater leaving denseperipheral rim, for fracturing.

Harder the nucleussmaller the wedge shaped sections.

All sections are left in the bag:To keep it distended ;

To keep ultrasonic turbulence in

bag.


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PHACO QUICK CHOP (PFIFER)

near vertical chopping.

Chopper pushed down, phaco tip moves

up and then both are laterally separated.

Prepare all fragments before emulsifyingto enable endo capsular phaco.

2mm exposure of phaco tip.


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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


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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..!!

RENT CONTROL ACTS !!!


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RENT CONTROL ACTS..!!!

The 10 commandments..1. FREEZE movements,reduce bottle height

2. inject visco from side port

3. stop irrigation

4. press reflux

5. withdraw phaco tip from AC

Assess damage-site , extent of rent.


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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

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