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Principles of Phacoemulsification

David A. Wilkie, DVM, MS, DiplomateACVO

ProfessorDepartment Chair

The Ohio State UniversityWilkie.1@osu.edu

Charles D Kelman MD 1930-2004

n �Father of Phacoemulsification�n 1962 - invented cryoproben 1966 - first animal phacon 1967 - first human phaco

- 76 minute phaco time- Inspired by dental unit

Phacoemulsificationn Technology and techniques are rapidly

evolving

This is a technology driven procedure

This is a technology driven procedure

You get what you pay for

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Phacoemulsificationn Handle

n Ultrasonic energy n Fluidics

n Irrigation n Bottle height

n Aspirationn Flow raten Vacuum

n Foot Pedaln Controls device

Phacoemulsification

n Ultrasonic phacon Electrical energy converted into

mechanical energyn Tip vibrationn Generates friction which creates

heat - thermal damage

Phacoemulsification

Phacoemulsificationn Older generation machines

n More energy n Increased thermal damage

Phacoemulsificationn Reuseable tips & tubing

n Cost effective?n How do you clean and sterilize???

n Disposablesn $/patient

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Should you re-use your materials?

Sterilization n Do Not gas your tubing or handpiecesn Gas does not sterilize areas that are

wet or have trapped liquidn Clean after each use

n Distilled watern Steam autoclave

n Routinen Flash

Phacoemulsificationn Power controlled by

frequency and stroke length

n Frequencyn 35,000 - 45,000

cycles/sec (Hz)n Lower frequency = less

efficientn Higher frequency =

excess heat

Phacoemulsificationn Stroke length

n 2-6 mil (thousands of an inch)

n Most operate at 2-4 miln (0.1-0.12mm)

n Longer the stroke lengthn Increased heatn Increased cavitationn Increased physical impact on

lens

Phacoemulsificationn Emulsification of lens

n Jackhammern Physically striking the lens

n Cavitationn “The formation and immediate implosion of

bubbles in a liquid”n High and low pressuresn Microbubblesn Implosion of microbubblesn Temperature at implosion of 13000o Fn Shockwave at implosion 75,000 PSI

Phacoemulsification

Cavitation

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Phacoemulsificationn Transducer

n 40,000 cycles per secondn Power related to stroke lengthn Destructive events

n Cavitationn Fluid and lens particles at tip reach velocities of 72 km/hrn Shock of the acoustical waven Mechanical impact of tip against lens

Phacoemulsificationn 15,30,45 degree cutting tips

n 45 degree - improved cutting efficiency, more difficult to occlude

n Flare tipsn Angled tips - Kelman

Phacoemulsificationn Various needle designs

KelmanFlare

Holding Strength

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Angle of the tip can be varied to facilitate occlusion

Phacoemulsificationn Minimal phaco energy is desired

n Stroke lengthn Presetn Foot pedal

n Durationn Efficient surgeonn Pulse or burst mode

n Emmisionn Tip selection

n Kelmann Flaredn 0, 15, 30, 45 degree

Preset

100%

50%

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Phacoemulsificationn Kelman tip

n Hard nuclein Flare tip

n Direct cavitation into tip

Phacoemulsificationn Fluidics

n Inflown Bottle height

n Outflown Incisionn Aspiration raten Vacuum preset and

demanded

Phacoemulsification

n Fluidicsn Irrigation

n Cooling at incisionn Maintain the anterior chamber

n Aspirationn Aspiration flow in ml/minuten Vacuum in mmHg

PhacoemulsificationInfusion bottle height-every 15cm above the eye = 11mmHg

Active fluidics

Phacoemulsification

n Fluidicsn Peristaltic

n Wheel with rotating bearings

n Venturin Compressed gas

n Diaphragmn Piston and valve

n Hybrid

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Phacoemulsification

n Irrigation/Aspirationn Peristaltic

n Wheel with rotating bearings

n Diaphragmn Piston and valve

n Venturin Compressed gas

Diaphragm

Phacoemulsificationn Peristaltic pumps �safer� as they take

several seconds to build to preset vacuumn More forgiving

n Diaphragm and Venturi pumps give preset vacuum immediatelyn More responsiven Better for posterior segment work

Irrigation Irrigation/Aspiration

Know where the aspiration reversal switch is

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Phacoemulsificationn Aspiration reversal

Phacoemulsificationn How to �Set the Dials�?n Goal is a �stable� eye. Not too soft, not

too hardn Just Right

Vacuum Settingsn Standard Phaco

n 20 mmHg minn 70 mmHg max

n Phaco Pulsen 28 mmHg minn 220-300 mmHg max

n I/An 26 mmHg minn 300 mmHg max

Vacuumn Do not need high vacuum when

sculpting as lens is stablen Higher vacuum for cracking, chopping

and fragments to �hold� will allow lower phaco energy

Phaco

Vacuum

Tip occlusion

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Phacoemulsificationn Surge

n Tip occlusion followed by fragmentation and immediate aspiration

n Shallowing of the chambern Newer technology addresses this

n Microprocessors sample vacuum/flow 50 times/sec

Higher the vacuum the greater the surge effect

Group L- 50 mm bottle height- Vacuum 80 mmHg- US time 117 +/-12s- Volume 165 +/- 54ml

Group H- 120 mm bottle height- Vacuum 150 mmHg- US time 96 +/-31s- Volume 255 +/- 33ml

Fluid in vitreous and anterior hyaloiddetachment

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n Fluid in the vitreousn Worse opposite entry siten > with longer irrigation timen > with increased fluidics

n Bottle heightn Vacuum

n Would stage of cataract and state of vitreous affect this?n Could be associated with:

n Retinal detachmentn Vitreous contamination and endophthalmitis

Phacoemulsificationn Pulse setting

Phacoemulsificationn Pulse/Burst Mode

n Decrease overall power deliveryn Provides deeper more stable A/Cn I choose to increase vacuum

setting to 300-350 mmHg max setting

n Think of increased vacuum as an extra hand in the eye to hold and pull the sculpted lens apart

Phacoemulsificationn Pulse/Burst Mode

n Pulse - Alcon Legacyn 50-150 msec of power followed by variable

period of aspiration only

n Burst - Allergan Sovereignn 80-120 msec of power followed by fixed short

period of aspiration

Phacoemulsificationn Whitestar®, Hyperpulse® technology

n �Cold Phaco�n Instead of 2-6 pulse/sec get 50

microbursts/secn No time to create thermal effectn Minimal cavitation

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Pulse PhacoK9 unstable lens

Coaxial standard phacovs.

High vacuum pulse phaco (350 mmHg)

Watch the lens movement decrease when switched to high vacuum pulse

Hydrodissectionn Inject BSS between capsule and cortexn Separates posterior cortex/nucleus from the

posterior capsule

Hydrodissectionn Better for 2-handed technique

n Divide & conquern Chip & flipn Phaco chopn CTR placement in unstable lens

n Lens free to rotate in the capsule bagn Less desireable for one-handed

coaxial phaco

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Hydrodissection + CTR Hydrodissection

Hydrodelineationn Injection of BSS into nucleus n Separates nucleus from the epinucleus

n Used for hard nucleus so epinucleus protects capsule

Phacoemulsificationn Trauma

n Time n Surgery time - 10-17 minutes/eyen Phaco time - 0-120 seconds/eye

n Fluid Volumen 50-200 ml/eye

n Turbulencen Phaco Energyn Chamber bounce

Intraocular Surgeryn �The enemy of GOOD is BETTER�

Phacoemulsificationn Surgeon must be adaptable

n Know more than 1 techniquen No one single method works on all

cataracts

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Phacoemulsificationn Divide and conquern Chip and Flipn Croissantn Phaco Chopn Stop and Chopn Other

Phacoemulsificationn One handed vs two handed technique

Zonules are like corn silk. They entwine and extend far posterior

Pull on the lens….You pull on the zonules

Pull on the zonules….You pull on the ora

Pull on the ora….You pull on the retina

And it may lead to…

Retinal tears, detachment

Phacoemulsificationn One-handed technique

n Sculpt a large, deep bowln Rotate lens and divide & conquer

n Crack the bowln Increase suction, use pulse

n Flip bowl over to phaco posterior aspectn Pressure at near side, push down and awayn Use suction to pull bowl over as it flips

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One-handed technique Coaxial forces

One-handed phaco

One-handed techniquePulse setting, Vacuum 300 mmHg One-handed technique

One-handed technique One-handed technique

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6 Year – old Diabetic DogPhaco -37 sec, 120ml Phacoemulsification

n Two-handedn Hard nuclein Unstable lensn Shorten surgical

time and decrease phaco power

n Zonular dehisence <120 degreesn 2-handed phacoemulsificationn Hydro-dissection + CTR and IOL in

the bag IOL or Sutured IOLn Zonular dehiscence >120 degrees

n 2-handed phacoemulsification or ICLEn Sutured IOL

THIS IS OFTEN AN INTRAOP DECISION

Lens Subluxation/Luxation n 2-handed phacon Hydro-dissection + CTR

and IOL in the bag IOL or Sutured IOL

n Zonular dehiscence >120 degreesn 2-handed phaco or ICLEn Sutured IOL

nZonular dehiscence <120 degrees

Phacoemulsificationn Two-handed

n Side-port incision 45o- 90o

from coaxial phacon 1mm keratomen When to perform?

n I choose to enter after phaconeedle in the eyen Can choose to switch mid-surgery

n Insert rotator, manipulator, choppern Retract into A/C when not in use

Two-handed conversion

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Choppers, manipulators

Warren C: Veterinary Ophthalmology 7:348-351, 2004Maggio F, et al: ACVO 2008

Phaco Chop

Divide & Conquer

Two-hand phaco for unstable lens

XX

Divide & Conquer

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Incorrect Divide & Conquer Incorrect Divide & Conquer

FDA Approved

n Stabilize the lens capsule when zonular weakness, degeneration, dehiscence is present

n Prevent capsular phimosisn When to implant?

n Pre or Post phacon Size selection

Capsule Tension Ring

n Size of CTR matches size of IOLn 12mm IOL = 12.5 mm CTRn 13mm IOL = 13.5 mm CTRn 14mm IOL = 14.5 mm CTR

Capsule Tension Ring

n Risks of CTR implantation?n 47 dogs, 94 eyesn One receives CTR, other is controln 1 yr follow upn No signif diff CTR vs no-CTR

Capsule Tension Ring

Hoy S, Wilkie DA, et al: CTR safety and complication rates in stable & unstable lenses. Veterinary Ophthalmology 11:426, 2008

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CTR Pre-phacoZonular dehiscence >120 degrees

240 degree instability-2 handed

300 degree Anterior luxationTwo Handed with vitrectomy and ECP

Pre-op IOP 32 mmHg

Complete Lens Luxation- anterior/posterior

Personally – I always try to remove by phaco. I NEVER use a cryo-technique

Medical vs Surgicaln Posterior entrapment plus a miotic

n No significant mean time to glaucoma or vision loss

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Phaco vs ICLEn Better vision preservation with surgery

vs. medical for subluxation vs luxationn Better success for Phaco vs ICLEn Retinal detachment

n 28% with ICLEn 6% with Phaco

n Glaucoman 60% have IOP concerns longterm -ECP

Manning S, Renwick P, Heinrich C, Cripps P: Lens instability in the dog: A retrospective study of surgical results in 102 cases (155 eyes). Vet Ophth 12:63, 2009

K9 Anterior lens luxation 2-hand phaco, vitrectomy, ECP

O�Malley Lens

Courtesy of Dr. Brian Gilger

K9 Posterior lens luxation 2-hand phaco

Want a high viscosity visco like 2% Acri-Syn

n Sabet® Lenticular Safety Net

Sabet® lenticular safety net

Cortical Aspiration

n ≥0.5 mm port required for canine cortex

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Cortical Aspiration Cortical I/A0.5mm curved

Bi-Manual Cortical I/ABi-Manual Cortical I/A

Capsule Vacuum

Value of this step??

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Capsule vacuum Capsule polish

Whitman Shepherd Capsule Polisher

n Removal of Viscoelastic

AcriVet 60V IOL Forceps fold acrylic IOL

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Modified ab-externo IOL

Wilkie DA, et al: A modified ab-externo approach for suture fixation of an intraocular IOL in the dog. Veterinary Ophthalmology 11:43-48, 2008

Modified ab-externo IOL

Wilkie DA, et al: A modified ab-externo approach for suture fixation of an intraocular IOL in the dog. Veterinary Ophthalmology 11:43-48, 2008

Ventral suture placement

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Dorsal suture placement -PMMA IOL

Dorsal suture placement -Duet® Forceps

IOL Placement Suture Fixation

Modified ab-externoCow Hitch Technique

Acrivet Acrylic IOL for Modified ab-externocow-hitch technique

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Acrivet Acrylic IOL for Modified ab-externocow-hitch technique

Ozil® torsional phaco

Active fluidics

Phacoemulsificationn Change is difficult, but not always badn We are now the �conventional

surgeons� and newer technologies are challenging us Dr Wilkie Dr Allgoewer

My new residents!!

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