Devgan. Phaco Fundamentals. Book

7/31/2019 Devgan. Phaco Fundamentals. Book

1/29phaco fundamentals

Supported by an unrestricted

educational grant from Bausch & Lomb

CME SERIES

phacofundamentalsFor The Beginning Phaco Surgeon


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WoRld RepoRt cme seRIes phaco fundamentals

Phaco Fundamentals 1.0An exploration of the basics of safe,

technically advanced cataract extraction

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Uday Devgan, MD, FACS

Uda Deva, MD, FACS is a caaac ad efacive sueo a he Maloe Visio Isi ue, he

pemie pivae ophhalmic pacice i Los Aeles, Califoia. He pefoms he full specum

of coeal ad leicula efacive ad esoaive sue ad has isuced housads of

sueos i 30 couies. D Deva is Chief of Ophhalmolo a Olive Vie UCLA Medical

Cee ad Associae Cliical Pofesso a he Jules Sei Ee Isiue a he UCLA School of

Medicie i Los Aeles, hee he is he ol facul meme o have eaed he pesiious eachi a ad

ice. D Deva ies mohl colums i muliple ophhalmic jouals oldide ad is a cosula fo

ma majo ophhalmic compaies. He ca e eached a .UdaDeva.com fo fuhe ifomaio.

1. The Basic Phaco Machine

2. Concepts of Fluidics

3. Flo Balance & Tubin Compliance

4. Optimiin Phaco Fluidic Settins

5. Fundamentals of Ultrasonic Phaco Poer

6. Continuous, Pulse, And Burst Phaco Modes

7. Hper Settins

8. Variable Dut Ccle

9. Variable Rise Time And Custom Settins

10. Creatin A Clear-Corneal Cataract Incision

11. Hand Position & Pivotin

12. Bevel Position; Incision Spacin

13. Foot Pedal Control Durin Steps Of Surer

14. Viscoelastics: Dispersive & Cohesive

15. Capsulorhexis Creation

16. Hdrodissection and Hdrodelineation

17. Concepts Of Nucleus Removal

18. Divide-and-Conquer Technique of Nucleus Removal

19. Stop-and-Chop Technique of Nucleus Removal

20. Quick Chop Techniques of Nucleus Removal

21. Cortex Removal

22. IOL Insertion

23. Incision Closure & Dressins

24. Post-op Medications & Follo-up

The causes of cataract are complex and

obscure, ranging from the unrelenting

forces of genetics and aging to the fate-

ful impacts of environment, climate,

diet, disease and trauma. Yet its effect

is simple: the progressive cloud-

ing of the eyes crystalline lens to

the point of opaqueness, robbing

the patient of sight. Medicines ef-

forts to slow or halt this progression

have failed. Yetas was obvious

even to the ancient Indian surgeon

Sushrutathe answer to cataract

lies in removing the obstruction to

restore the passage of light onto the

macula. The history of cataract sur-

gery has been an unremitting quest

to remove the obstaclethe no-

longer-crystalline lens. Sushrutas

genius was simply to nudge the ob-

struction aside, a procedure called

couching that persisted well into modern times. The

machine age saw attempts to extricate the lens via

incision, but it wasnt until the second half of the

20th century that surgeons, empowered by micros-

copy and precision implements, nally succeeded at

cataract extraction.

Intracapsular cataract extraction involved removal

of the lens and capsular bag as one, with the refrac-

tive power of the now-absent lens provided exter-

nally by massive Coke bottle spectacles. Its hard

to believe today that ICCE was the state of the art

as recently as 1980. Sir Harold Ridleys observation

that World War II aviators could tolerate shards of

aircraft canopy glass in their eyes prompted him to

use that materialactually polymethylmethacrylate,

or PMMAto fashion the rst intraocular lenses.

Ridleys innovation inspired surgeons to r emove the

opaque lens while leaving intact the

capsular bag as a receptacle to hold

his IOLs, and extracapsular cata-

ract extraction was born. ECCEs

breakthrough was the capsulotomy,

removal of the anterior capsule to

allow wholesale delivery of the

nucleus, to be replaced by a PMMA

lens with known refractive quali-

ties. Its a nifty trick that remains

in many eye surgeons repertoires,

and a staple of most residency train-

ing programs. Renement of ECCE

technique led to extraction via

smaller incisions that afforded sta-

ble intraocular pressure during sur-

gery and sealed without sutures, a variation called

manual small-incision cataract surgery. With SICS

and low-cost IOLs, cataract surgery now penetrates

even the worlds poorest communities and surgical

volumes have risen into the millions.

Yet the sheer mass of the cataractous lens posed a

physical barrier to smaller, less-traumatic incisions.

Charles Kelman toppled this barrier with his idea of

emulsifying the nucleus inside the eye for removal

via aspiration, a task accomplished with targeted

ultrasound and dubbed phacoemulsication. Inci-

sions have been shrinking ever since, with advances

the machine age saw

attemPts to extricate

the lens via incision,

but it wasnt until

the second halF oF

the 20th century that

surgeons, emPowered

by microscoPy and

Precision imPlements,

Finally succeeded at

cataract extraction.


3/29


in computer control and engineering and successive

generations of foldable IOLs allowing surgeons

to all but replicate the human lens with minimal

trauma to the eye. The incision-size benchmark for

commercially available systems now has dropped

below 2mm, as with Bausch & Lombs 1.8mm Stel-

laris platform and its Akreos MI60 foldable

intraocular lens.

While phacoemulsication has become the prevail-

ing standard in the industrialized world, where cata-

ract usually is treated in its early stages before the

patients vision is dramatically impaired, this is not

the case in much of the world. In India and China,one can still encounter almost the entire history of

cataract surgerya relatively even mix of ECCE,

SICS and phaco punctuated by isolated pockets of

ICCE and, by some experts telling, even linger-

ing instances of couching. See gure 1. The good

news is that advanced surgical skills are spreading in

both countries. Surgeons are moving rapidly toward

phacoemulsication as more and more patients, in-

creasingly aware of the benets of early interven-

tion, are expecting their ophthalmologists to use the

latest technologies.

But what exactly is phacoemulsication? While its

easy to conceptualize, its actually one of the most

complex forms of microsurgeryinvolving simul-

taneous machine-controlled irrigation and aspiration

to maintain anterior chamber stability, even while

the ultrasound tip manipulates and blasts away at

the nucleus. Theres a lot that can go wrong, and top

surgeons say the best defense against complications

is to know the technology as well as the procedure.

The purpose of this book, a compilation of the 24-

part Phaco Fundamentals series that was rst syndi-

cated in Ophthalmology World Report, is to establish

a foundation of knowledge about all aspects of the

phacoemulsication system, its processes and its op-

erations. The author, Dr. Uday Devgan, is a renowned

U.S. surgeon in private practice at the Maloney Vi-

sion Institute in Los Angeles and associate clinical

professor of ophthalmology at the Jules Stein Eye

Institute in the School of Medicine of the University

of California, Los Angeles. Dr. Devgan has dedicat-

ed a large part of his teaching to understanding and

explaining the fundamentals of phaco in ways that

demystify the technology, and empower surgeons to

use it safely and to maximum advantage.

The Phaco Fundamentals series has given our World

Report editorial team a unique glimpse into the state

of cataract surgery in both India, where our circu-

lation exceeds 10,000 ophthalmologists, and China

where we have 17,000 registered readers. This com-

piled edition was requested by more than 3,000 doc-

tors in China and 1,100 in India, and each provided

a snapshot of their current practice. The compiled

data, comprising one of the largest surveys of cata-

ract ever undertaken in either country, revealed a

wide range of surgical skills and experienceand

a strong hunger for knowledge and surgical oppor-

tunity. In India, only about 14% of re spondents de-

scribed their phaco skills as advanced, while 80%

placed themselves in the basic or intermediate cat-

egory. See gure 2. In both countries, doctors over-

whelmingly cited the cost of equipment as the main

barrier to their own adoption of phaco. Nonetheless,

the survey showed that Indian and Chinese ophthal-

mologists hold phaco in high regard, saying it was

attractive for clinical reasonsanterior chamber

stability, low rates of induced astigmatism, lower

rates of infection and other complicationsas well

as practical ones such as patient comfort, reliability

and competitive market advantage. The study cap-

tured data about more than 2,000 phaco machines,

showing that large numbers are 4-5 years old and

likely to be replaced soon. See gure 3. Respon-

dents said their No.1 requirement in a replacement

system was affordability, followed by user friendli-

ness and ability to maintain a stable anterior cham-

ber during surgery.

About 70% of the 4,100-plus respondents said Phaco

Fundamentals was pitched to a comfortable level of

difculty, but they also presented a long list of ideas

for further studysuggestions that editors are using

to design the next cycle, which we are calling Pha-

co Fundamentals 2.0. Were preparing chapters on

many aspects of phaco practice, including the learn-

ing curve when transitioning to phaco from ECCE or

SICS, the different types of phaco systems, various

IOL types and applications, typical complications

and their management and pearls of best practice.

The editors of Ophthalmology World Report wish to

thank Dr. Uday Devgan for his brilliant insights and

clear explanations. And we thank Bausch & Lomb

for the unrestricted educational grant that made

Phaco Fundamentals possible. Finally, we wish to

thank the thousands of World Report readers who

requested the compilation and provided their views

and suggestions.

Jeffrey Parker

Editorial Director

Ophthalmology World Report

PHACO SICS ECCE Other

35%

12%13%

45%55%31%

9%

5%

42%

50%

3%

WHAT IS YOUR PREFERRED

CATARACT TECHNIQUE?Sample size: 1107

1-3 Yrs 4-6 Yrs 7-9 Yrs 10 Yrs& above

HOW OLD IS

YOUR PHACO MACHINE?Sample size: 779

Basic Intermediate Advadced

EVALUATE

YOUR PHACO SKILLSSample size: 1060

F 1 F 2 F 3


4/29


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maazie. yr sr eirial s rai-

ali is reall ell r me i m wr. I e

see mre ariles ab e maaeme

post-cataract complications and difcult cases

as well as e erseies a exeriees

exers rm er sials, wi a irm

m w raie. I als areiae r rer-

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IAM A REguLAR REAdER Wrl

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WIth A popuLAtIon of 1.3 bil-

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a e se r eelme is as. pa

ees be wiel rme a raize...

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d hp, y, J P

ophthALMoLogy Wrl Rer

as eare e amirai ma

reaers r is exelle rers,

see issemiai wlee a qal-

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all areiae i. cmare (is reeessr)

oalml times, oalml Wrl

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blises e laes irmai ab srial

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isi i aal a erais.

h h,

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IM An ophthALMoLogISt a a

lal reaer. Ie se 20 ears a e

rassrs, ieeri a srer

for cataract, and nd the magazine to be very

ell. I sae eer isse Wrl Rer as a

reeree, b m se is imlee s I reall

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fameals....

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part to come out with a very simplied

e mreesie series a

ameals, wi is er sel r resies

lie me

g m,

s r u, c

ophthALMoLogy Wrl Rer

arries a l aara erae

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series is reall . I lie see s se-

rial erae er is . I eseialllike reading your Cover Story proles, which

ire raiiers wr a areer e-

elme. yr reri b srer a

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IAM vERy Much imresse b dr.

ua deas pa fame-

als series. I wis ae e ll se-

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a Bas & Lmb r eri e ble

eri all 24 lesss a are

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phthALMoLogy Wrl Rer

as beme a imra wi-

w r wi I lear ab

ew liial eiqes, aaes a ieas.

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now embracing phacoemulsication. For a rel-

aiel iexeriee r lie me, Im ee

bai a elemear wlee a

r r maazie a e a r-

ie ai/isal iss a er raii ma-

erials. te sa as!

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s e r lies liial raie

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fameals series, rm

which I have proted deeply.

My hospital doesnt yet have phacoemulsica-

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r maazie. tis wa, i iis ermi

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a exe e e series mae i ee mreslei

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5/29


The BasicPhaco MachineALL PHACO PLAtFOrMS SHArE tHE SAME bASIC StrUCtUrE AnD COnCEPtS. tHEPHACO MACHInE AIMS tO bALAnCE FLUIDICS wItHIn tHE EyE, wHILE DELIVErIngULtrASOnIC EnErgy AnD VACUUM In OrDEr tO EMULSIFy AnD ASPIrAtE tHECAtArACt tHrOUgH A SMALL InCISIOn.

ally works by depressing it towards the oor with the

dominant foot (the right foot for most surgeons). Each

foot pedal position is additive to the previous positions,

so that while the pedal is in position 2 (vacuum/aspira-

tion) it is also providing the full function of position 1

(irrigation). Similarly, once the pedal is in foot position

3 (ultrasound energy), it is also providing the function

of position 2 (vacuum/aspiration), as well as position 1

(irrigation). [ F 1 p f. ]

FOOT POSITION 1: IRRIgATION

Its important to realize that during phacoemulsica-

tion, we are working in the very small space of the

anterior and posterior chambers, compromising well

under 1 cubic centimeter of space together. During

the surgery we must always maintain the stability and

structure within the eye, particularly to prevent col-

lapse of the anterior and posterior chambers which can

lead to severe c omplications.

The irrigation function of the phaco machine is meant

to provide a source of uid infusion into the eye during

the surgery. By depressing the foot pedal to position 1,

the infusion is turned on. There is no linear control of the

infusionthe infusion is either turned on or turned off.

The height of the infusion bottle determines the rela-

tive infusion pressure and ow rate during the sur-

gery. To keep the eye inated during surgery, we need

to ensure that the uid inow rate is greater than the

uid outow rate.

[ Figure 2: Irrigation of uid into the eye is the function of phaco foot

p 1. ]

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FOOT POSITION 2:

VACUUM / ASPIRATION OF FLUID

Phaco foot position 2 is the control of the relative aspira-

tion and vacuum level of the uid from the eye. There

is a linear control of vacuum and ow, so that the top

of foot position 2 provides less vacuum or ow than the

middle or bottom range of the same foot position 2. This

is similar to the gas pedal in a car, where the cars throttle

is opened more as the gas pedal is further depressed. To

create the vacuum and the aspiration ow of uid, the

phaco machine must have a uid pump. The most com-

mon types of uid pumps are peristaltic and venturi,

and these will be explained fully in future columns.

The vacuum and aspiration levels that are created draw

the uid out of the eye and into a waste uid collec-

tion via the outow tubing. The regulation of vacuum

and aspiration is controlled by the foot pedal, with more

depression of the pedal resulting in higher levels. There

are two primary sources of uid outow during phaco-

emulsication: the outow from the phaco probe cre-

ated by the uid pump, and the leakage of uid from the

incisions. [ Figure 3: Vacuum and aspiration of uid from the eye is

f f p f p 1. ]

FOOT POSITION 3: ULTRASOUND ENERgy

The bottom-most position of the foot pedal is position

3, which controls the delivery of ultrasound energy into

the cataract. There is linear control of the ultrasound

energy level so that further pedal depression results in

more ultrasound energy, such as would be needed for a

denser cataract. Note that if the pedal is in position 3,

we are already engaging the full function of both posi-

tions 1 and 2. The irrigation is on, and the vacuum and

aspiration level is at its highest preset level. Ultrasound

energy should only be applied once the tip of the phaco

probe is in contact with part of the cataract.

When we look at the phaco probe closely, we see that

there are three lines attached: (1) the infusion tubing

carrying uid into the eye, (2) the outow tubing that

removes the uid via ow that is created by the phaco

machines uid pump, and (3) the line that carries the

electrical signals to control the ultrasound energy at the

tip of the phaco probe. These three lines correspond to

the three phaco foot pedal positions.

[ F 4: F p p 3 f

. ]

The three main functions of the phaco machine

are: (1) to provide irrigation into the eye, (2) to

create vacuum/aspiration to remove the cataract,

and (3) to deliver ultrasound energy in order to emulsi-

fy the nucleus. These three functions correspond to the

three phaco foot-pedal positions. The phaco foot pedal

is the primary instrument used to c ontrol the phaco ma-

chine during cataract surgery. This foot pedal tradition-

F 1


6/29

0 WoRld RepoRt cme seRIes phaco fundamentals

Concepts of FluidicsDUE tO tHE SMALL VOLUME OF tHE AntErIOr AnD POStErIOr CHAMbErS, tHECOntrOL OF FLUIDICS DUrIng PHACOEMULSIFICAtIOn SUrgEry IS IMPOrtAnt tOEnSUrE EFFICIEnt rEMOVAL OF tHE CAtArACt wHILE PrEVEntIng COMPLICA-tIOnS DUE tO tISSUE COLLAPSE.

phaco uidics is to keep the inow greater than the out-ow. [ Figure 1: Keep inow greater than outow to ensure stability

f . ]

MODULATINg PHACO FLUID FLOw:

POISEUILLES EQUATION

The basic equation that governs all uid ow during

phacoemulsication surgery is Poiseuilles Equation:

F = P r / L

In this equation, F = ow, P = pressure gradient, r =

radius of the tube, = viscosity of uid, and L = length

of the tube. We are concerned with the relative relation-

ship and not the exact values, therefore, for simplicity

we can simplify this formula. The viscosity of the uid

is relatively constant, as is the length of the tubing. And

the values of pi and 8 are constant. This leaves us with

a simpler equation: F ~ P r

Flow is proportional to the change in pressure times the

radius of the tubing to the fourth power. Because the

value for tubing size is exponential, a small change to

the radius results in a large change in the relative ow.

This is clearly illustrated in a common sense situation

of drinking with straws. [ F 2: P eq

(a) q

lower ow, as compared to larger bore tubing (B) which can achieve a

high ow with less vacuum required. The change in ow is exponen-

f . ]

MODULATINg FLUID INFLOw

The source of uid inow is the bottle of balanced salt

solution that is hanging on the phaco machine. The

two factors that determine the rate of inow are: the

change in pressure and the radius of the inow tubing.

The change in pressure, can be modulated by raising

or lowering the height of the bottle relative to the pa-

tients eye: the higher the bottle, the higher the infusion

pressure. The inow tubing has a large radius in order

to maximize the ow and make sure that we keep our

inow greater than the outow. Similarly, the size of

the infusion channel within the phaco probe (or other

infusion instrument) is kept as large as possible so as to

not cause a bottleneck effect. [ Figure 3: Fluid inow can be

f p

gradient, as well as changing the radius of the inow tubing. ]

MODULATINg FLUID OUTFLOw

For uid outow, there are two sources of uid leav-

ing the eye: (1) the uid that is removed via the phaco

probe as a result of the vacuum level generated by the

uid pump, and (2) uid leakage from the incisions.

The rate of the uid outow via the phaco needle is

determined by the radius of the needle and tubing, as

well as the change in pressure generated by the phaco

machines uid pump. The rate of the uid outow loss

via the incisions depends on their size and the relativet of the instruments within these incisions.

Some degree of uid leakage from the incisions is help-

ful to allow cooling of the phaco needle and to prevent

thermal injury during surgery, particularly in early in

the learning stages of phacoemulsication. With the

use of advanced phaco power modulations, more ex-

perienced phaco surgeons tend to move towards tighter

incisions which can give more stable uidics.

The composition, nature, and size of the inow and

outow tubing are different.

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8/29


Optimizin PhacoFluidic SettinstHE CHALLEngE OF CAtArACt SUrgEry ArISES In LArgE PArt FrOM tHE SMALLCOnFInES OF tHE wOrkIng SPACE. tHE AntErIOr AnD POStErIOr CHAMbErCOMbInED tyPICALLy COMPrISE LESS tHAn 1 CUbIC CEntIMEtEr OF SPACE AnDPrOVIDE VEry LIttLE rOOM FOr ErrOr. tHE FUnCtIOn OF tHE PHACO FLUIDICS

IS tO bALAnCE tHE InFLOw AnD OUtFLOw OF FLUID In OrDEr tO MAIntAIn tHEwOrkIng SPACE, brIng CAtArACt MAtErIAL tO tHE PHACO tIP, AnD PrEVEntCOLLAPSE OF tHE EyE. OPtIMIzIng tHE PHACO FLUIDIC SEttIngS IS InStrUMEntALtO tHE EFFICIEnCy AnD SAFEty OF PHACOEMULSIFICAtIOn SUrgEry.

With a typical peristaltic phaco machine plat-

form, the most common type in the US mar-

ket, there are only a few parameters that are

adjustable: the bottle height, the ow rate, the maxi-

mum vacuum level, and the phaco needle size.

Perhaps the most important parameter is the selection

of phaco needle size. From our previous lesson, we re-

call that the difference in ow between a larger bore

needle and a small bore needle varies exponentially

due to Poiseuilles Equation. In summary, the smaller

bore phaco needles are suited for high-vacuum, low-

ow uidics, while the larger bore needles are better

suited for high-ow, low-vacuum uidics. The analogy

of drinking a milkshake via a small bore cocktail straw

versus a larger bore drinking straw works well to il-

lustrate this point.

The ow rate for a peristaltic machine is typically giv-

en in cc of uid per minute. This is determined by the

rate at which the peristaltic rollers milk the uid along

the outow tubing. With the phaco needle unobstructed

the maximum ow rate is achieved and in large part,

determines the speed at which things happen in the eye.

Upon occlusion of the phaco needle with cataract ma-

terial the ow rate declines and approaches zero. The

ow rate determines the speed at which things happen

in the eye during phacoemulsication.

The bottle height determines the inow rate of uid into

the eye. Very much like a water-tower in a small town,

the height of the uid above the eye creates a force-

ful infusion of uid via gravity: the higher the infusion

bottle, the greater the inow pressure and inow rate.

With an unobstructed phaco needle, the ow rate is at

the maximum, but the vacuum level is very lowvery

far from the maximum vacuum level that the surgeon

has selected. The vacuum level in a peristaltic-based

system is only achieved upon occlusion of the phaco

tip. (Figure 1) The higher the vacuum, the greater the

holding powerand the holding power is used to xate

the cataract while we mechanically chop it. The effect

of the vacuum level varies with the bore of the phaco

needle due to the effect of surface area. The larger the

cross-sectional surface area of the phaco needle, the

greater the holding power given the same amount of

vacuum. The vacuum level determines the holding

power or grip of the phaco tip onto nuclear pieces.

OPTIMIzINg yOUR SETTINgS

In order to optimize the phaco uidic settings, it is im-

portant to match the parameters to the technique and

the surgeons preference.

The rst decision is the selection of phaco needle size,with the most common sizes being the smaller-bore

0.9mm needle and the larger bore 1.1mm needle size.

If your preference is a quicker procedure with rapid

nucleus removal, the larger 1.1mm needle size is pre-

ferred since it will give a signicantly greater ow rate.

If your preference is a slower but more controlled pro-

cedure, then the smaller-bore 0.9mm needle is more

suited to your technique.

The bottle height determines the inow of uid into the

eye. In order to help prevent surge, it is important to

keep the inow of uid greater than the outow of uid

at all times. The inow of uid comes from only one

source, the bottle of balanced salt solution, while the

outow of uid comes from two sources, the suction

via the phaco needle and the leakage from the incisions.

If, at any time, the outow out-strips in the inow, the

eye will collapse and there is a high likelihood of pos-

terior capsule rupture. It is often advantageous to start

with a high bottle height to ensure a sufcient inow

of uid, and then to taper it downwards to minimize

the posterior displacement of the lens-iris diaphragm

due to the infusion pressure. If you sometimes notice

corneal striae and anterior chamber instability during

your surgery, you may benet from increasing the bot-

tle height.

For phaco chop, holding power of the nucleus is impor-

tant in order to securely xate it while using the chopper

to mechanically disassemble the nucleus. This requires

a relatively high vacuum, such as 200-250 mmHg with

the 1.1mm needle, or 300-400mmHg with the 0.9mm

needle. Once the nucleus has been broken into smaller

fragments, the speed at which the fragments are attract-

ed to the phaco tip is determined by the peristaltic ow

rate, with 20cc/min being very slow and 50cc/min be-

ing very fast. The same vacuum and ow rate settings

can be used for the entire nucleus removal procedure

during phaco chop.

For divide-and-conquer, there are two distinct parts

of nucleus removal: sculpting of the nucleus and then

quadrant removal, and different uidic settings are

required for each. For grooving and sculpting of the

nucleus, the work is being done by the ultrasonic en-

ergy and thus the ow and vacuum settings are quite

low just enough to aspirate the nuclear material re-

moved from each forward stroke of the phaco probe.

A vacuum level of less than 100mmHg and a ow rate

of less than 30cc/min is sufcient for this purpose. For

quadrant removal, a moderate amount of holding pow-

er is required to bring each quadrant into the phaco tip.

Using a higher vacuum level of 200-300mmHg and a

ow rate of 30-50cc/min, depending on the needle size,

is typically sufcient for this purpose.

With knowledge of the concepts behind the variables,

it is easy to tailor the uidic settings to the surgeon

and technique. Understanding the concepts behind the

phaco uidic settings is instrumental in optimizing the

parameters for increasing the efciency and safety of

your phaco technique.

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lesson 04


9/29


Fundamentals ofUltrasonicPhaco PowertHE PHACO ULtrASOUnD PrObE DELIVErS EnErgy IntO tHE EyE tHAt CAn

bE USED tO brEAk UP tHE CAtArACt tO FACILItAtE EMULSIFICAtIOn AnDASPIrAtIOn. It ACCOMPLISHES tHIS by VIbrAtIng At A FIxED FrEqUEnCy wHEntHE FOOt-PEDAL IS DEPrESSED tO POSItIOn tHrEE. wHEn wE tItrAtE tHEAMOUnt OF ULtrASOUnD EnErgy wE PLACE IntO tHE EyE, wE ArE kEEPIngtHE FrEqUEnCy COnStAnt bUt wE ArE InCrEASIng tHE StrOkE LEngtH AnDtHErEFOrE, tHE tOtAL AMOUnt OF EnErgy.

The stroke of the phaco needle creates a mechani-

cal impact as the metal phaco needle hits the cata-

ract material. It also creates cavitation and implo-

sion as a microvoid is created just in front of the phaco

needle. A uid and particle wave is propagated into the

cataract material, and heat is created as a by-product. It

is important to avoid choosing phaco power settings that

cause excessive heat build-up as this can burn the cornea

and damage the delicate ocular structures.

The phaco pinch test is a simple way to determine if

your ultrasound power settings are likely to cause an

incision burn in the eye. During wet lab testing, pro-

gram your selected settings into the phaco machine,

remove the protective silicone sleeve from the phaco

needle, grasp the needle between your ngers, and

push the foot-pedal all the way down. If your settings

cause excessive heat build-up, the needle will get hot

and may even burn your ngers. But its better to singe

your ngertips than fry your patients cornea.

During surgery, the phaco machine keeps track of the

average phaco power, given as a percentage of maxi-

mum, as well as the total time during which phaco ul-

trasonic power was delivered. These are displayed as

U/S AVE, which stands for ultrasound average and

EPT, which is elapsed phaco time.

We can measure and compare the amount of phaco en-

ergy that we use in surgery by calculating the APT: Ab-

solute Phaco Time. This is done by multiplying the U/

S AVE by the EPT, which the phaco machine does

for us automatically, and it displays as the APT.

It makes sense that if you deliver 15 seconds of energy

at 100% power, it is about the same as 30 seconds at

50% power, or 60 seconds at 25% power. This is be-

cause for each of these three examples, the APT (Abso-

lute Phaco Time) is 15 seconds.

It is important to give as little ultrasonic phaco energy

as possible during the cataract surgery. The ultrasonic

energy can easily damage the corneal endothelial cells,

and excessive phaco energy can cause pseudophakic

bullous keratopathy and corneal decompensation. The

most important way to decrease the APT is to use a me-

chanical method of nucleus disassembly such as phaco

chop. This is far more efcient than techniques like di-

vide-and-conquer, resulting in less energy delivery as

well as shorter operative time.

To maximally decrease the APT, we need to decrease

both the average phaco power and the phaco time. The

average phaco power can be decreased by limiting the

foot pedal depression in position three or by decreasing

the maximum phaco power level on the machine.

The phaco time can be decreased by applying the ul-

trasonic power when cataract pieces are at the phaco

tip and are not aspirated by the vacuum forces alone.

Additionally, phaco time can be reduced by deliver-

ing smaller pulses or bursts of phaco energy instead

of continuous ultrasound. This method of breaking up

the ultrasonic energy into smaller packets of pulses and

bursts is called phaco power modulation and it will be

the subject of the next lesson.

With optimized ultrasonic phaco power parameters, it

is possible to remove cataracts with less than 1 second

of absolute phaco time, yielding immediate clear cor-

neas and happy patients.

lesson 05

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F 3 F 4


10/29


Continuous, Pulse,And Burst PhacoModestHE bASIC POwEr SEttIngS ArE COntInUOUS, PULSE, AnD bUrSt. In tHE

COntInUOUS POwEr SEttIng, COntInUOUS EnErgy IS DELIVErED wItH VArIAbLEPOwEr DEPEnDIng On HOw LOng tHE FOOt PEDAL IS DEPrESSED. tHE MAxIMUMPOwEr SEttIng CAn bE PrESEt AnD tHEn OnE HAS COntrOL OF tHE MAxIMUMAMOUnt OF PHACO POwEr DELIVErEDtHE LOngEr tHE FOOt PEDAL ISDEPrESSED, tHE grEAtEr tHE PHACO POwEr.

In the pulse mode, the pulses of energy delivered

have variable power depending on how long the

foot pedal is depressed. The more time it is de-

pressed, the greater the power of each sequential pulse

of energy. The dening feature of pulse mode is that

after each pulse of energy delivered, there is a period

of time in which no energy is delivered between in-

creasing periods of energy, the off period. Alternat-

ing between the on and off pulse, reduces heat and

delivers half the energy into the eye.

Finally, in burst mode, each burst of energy has the same

power but the interval between each burst increases as

the foot pedal is depressed: The further the foot pedal

is depressed, the shorter the off period between each

burst. As a result, at maximum foot pedal depression,

the bursts of energy will become continuous delivery of

energy. When referring to modulations of phaco pow-

er, the terms burst and pulse may seem similar, but

they refer to two entirely different concepts.

Surgeons are familiar with the concept of continuous

phaco energy which is delivered in a linear fashion:

as the phaco foot-pedal is depressed, the energy level

increases. Pulse mode simply gives the same linear

control of phaco energy, however the energy is always

phaco machine to aspirate the cataract and then give

small bursts of phaco energy only when necessary. Be-

cause we can program these bursts of phaco power to

be very short (as quick as a few milliseconds), we can

effectively give hundreds of tiny bursts and still total

less than 1 second of total phaco time.

Because the phaco foot-pedal now controls the rest in-

terval between identical bursts, we do not have linear

control of the phaco power level. For this reason, it is

important to use a lower phaco power setting when

using burst mode as compared to pulse or continuous

modes. When the foot-pedal is maximally depressed,

the rest interval between bursts is zero and the phacoprobe essentially delivers continuous energy.

For surgeons using a divide-and-conquer technique of

surgery, the foot-pedal can be maximally depressed

during grooving, thereby delivering continuous phaco

energy to facilitate sculpting of the nucleus. Then to

remove the quadrants, the foot-pedal is only partially

depressed in position 3 so that only bursts of phaco

power are used for segment removal. Finally, for the

epi-nucleus removal, the foot position 3 is barely en-

tered, and just a few bursts of energy are delivered for

removal of the softer cataract portions.

Most phaco machines have two settings for burst mode:

single burst and multiple burst. Single burst delivers

just one single burst of energy, for burying the phaco

probe into a nucleus for chopping. I do not ever use this

mode, but instead prefer multiple burst mode because I

can still deliver just one single burst by barely entering

foot-position 3, and I still have the ability to deliver

many more bursts and varying intervals with further

foot-pedal depression.

For my technique of quick-chop, I typically use just

one phaco setting: Multiple burst mode, with a burst

time of 20 milliseconds, a power of 10%, and an end-

point duty cycle of 50%. This means that I can give

50 of these identical bursts at 10% power to equal just

one second of continuous phaco at 10% power. Or in

absolute terms, I can give 500 of these identical bursts

at 10% power to equal just one second of continuous

phaco at 100% power. It comes as no surprise that most

cataracts can be removed with an energy equivalent

that is less than 2 seconds of absolute power at 100%.

lesson 06

delivered in pulses. Burst mode denes a specic and

identical burst of phaco energy, then as the foot-pedal

is depressed, these identical bursts of energy are deliv-

ered more rapidly, until the interval of time between

bursts is innitely small.

Burst mode allows a true phaco-assisted aspiration of

the lens nucleus. We use the vacuum and uidics of the

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F 2, 3, 4

F 1


11/29


lesson 07

Hper SettinstHE rAngE OF PrOgrAMMAbILIty OF tHE PULSE AnD bUrSt PHACO SEttIngSHAS ExPAnDED COnSIDErAbLy. wHILE PrEVIOUS gEnErAtIOnS OF PHACOPLAtFOrMS HAD PULSE rAtES OF UP tO 20 PULSES PEr SECOnD, tHE nEwErgEnErAtIOn MACHInES HAVE tHE AbILIty tO DELIVEr UP tO 120 PULSES PErSECOnD. SIMILArLy, tHE OLDEr MACHInES HAD bUrSt wIDtHS AS nArrOw AS 30MILLISECOnDS, wHILE tHE nEw PLAtFOrMS ArE AbLE tO DELIVEr bUrSt wIDtHSAS FInE AS JUSt 4 MILLISECOnDS.

The advantage of this upgraded range of program-

mability is the smoothness and precision of pow-

er delivery. With the standard settings in pulse

mode, where each pulse is as long as each rest period,

the pulse mode can deliver good cutting power with half

the energy of continuous phaco energy. [ F 1 ]

The more pulses per second we can give, the smoother

the power delivery will bevery similar to serrations

on a knife. If we want to harness the sculpting and cut-

ting ability of the phaco hand-piece for grooving of

the cataract nucleus, it makes sense that a knife with a

smooth blade would cut well. A coarsely serrated knife

with large, widely spaced serrations would not cut as

smoothly. However if we use a very nely serrated

knife, it would likely cut the best of all. Using a very

high pulse rate of 100 or more pulses per second results

in the cutting ability of a very nely serrated knife, yet

delivers half of the energy of continuous phaco power.

[ F 2 ]

Hyper settings in burst mode allow ner and more pre-

cise delivery of bursts of phaco power. If we use con-

tinuous phaco energy mode and try to use our foot to

deliver small bursts of phaco power, the best we can

do is about a half-second of energy per pulse, which is

500 milliseconds. Using the newer hyper settings we

can set a burst mode as small as 4 milliseconds, which

is 125 times ner and more precise than using manual

control by the surgeon.

Modern surgery is primarily phaco-assisted aspira-

tion of the nucleus. The majority of the forces that are

used to remove the nucleus from the eye are uidic

forcesthe ow, aspiration, and vacuum forces. The

ultrasonic power delivery is there to assist the uidics

once a denser piece of nucleus is encountered. My pre-

ferred setting for phaco surgery is burst mode, with a

very ne burst width. As the pedal is depressed further

in foot-position 3, the rest interval between bursts de-

creases until the burst width and rest interval are equal,resulting in a 50% duty cycle. The effective number

of bursts per second increases as the rest interval de-

creases and using a burst width of 5 milliseconds and

allowing 5 milliseconds of rest between each burst, the

maximum number of bursts per second is 100. (Math: 1

second / 10 millisecond cycle = 100 bursts per second).

This results in being able to effectively control the duty

cycle and the burst rate per second at the same time via

the foot-pedal.

For surgeons who wish to continue to perform their

standard technique of phaco-emulsication, simply

changing from continuous phaco power to a hyper

pulse rate of 100 pulses per second will allow them

to cut the energy delivery in half. This halving of the

ultrasound energy will result in less endothelial cell

damage, less heat production, and clearer corneas and

sharper vision immediately post-op. For surgeons who

perform the divide-and-conquer method of nucleus dis-

assembly, make the switch to a hyper pulse mode and

you will immediately perform better surgery without a

change in your technique.

Changing the number of pulses per second does NOT

change the amount of power delivered into the eye.

Whether we give 2 pulses per second or 8 pulses per

second, note that the total energy, as represented by the

green blocks, is the same. [ F 3 4 ] The same

applies when we compare 10 pulses per second to 100

pulses per second. The reduction in the amount of en-

ergy delivered is due to the ratio of the on:off pulses,

which is known as the duty cycle. In our next lesson,

we will explain duty cycles and their effect on phaco

power delivery.

F 1

F 2, 3, 4

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12/29


LESSON 08

Variable Dut CclewHEn wE CHOOSE A MODE SUCH AS PULSE MODE, wHICH ALtErnAtES PHACOPOwEr PULSES wItH PErIODS OF rESt, tHE DEFAULt rAtIO IS 50:50.tHIS IS CALLED A 50% DUty CyCLE, AS EACH COMPLEtE CyCLE IS COMPOSED OFEnErgy On FOr 50% OF tHE tIME, tHEn EnErgy OFF FOr 50% OF tHE tIME.tHIS DEFAULt rAtIO CAn bE CHAngED tO ALtEr tHE rAtIO OF ULtrASOUnDEnErgy tO tHE rESt IntErVAL.

Ultrasound energy creates helpful cavitation and

mechanical forces that are used to break up

the cataract nucleus; however, this energy also

can create signicant heat. The jack-hammer effect of

ultrasound energy can cause repulsion of the nuclear

fragments from the phaco tip. It is helpful to alternate

periods of phaco energy with rest periods, as the rest

periods are when we achieve cooling of the phaco

needle and aspiration of the nuclear fragments. If we

change the ratio of the on period, when ultrasound en-

ergy is delivered, to a shorter duration, then we can fa-

vor the aspiration and cooling of the phaco needle over

the heat generation and jack-hammer repulsion effects

of the ultrasound. [ F 1 ]

To program in a change in this ratio, there are two dis-

tinct methods: entering a new duty cycle or direct pulse

programming. For example, if I am using 10 pulses per

second and Id like to slightly reduce the ultrasound

energy, I can decrease it from a 50% duty cycle to a

40% duty cycle. This can be done by dropping the duty

cycle ratio as seen on the control panel of the phaco

platform. Alternatively, I can delineate the specic on

and off periods for each cycle, with an on-time of 40

milliseconds followed by an off-time of 60 millisec-

onds, I will achieve the same resulta total cycle time

of 100 milliseconds, with 10 pulses per second and a

40% duty cycle. [ F 2 ]

In the pulse mode, the default duty cycle is 50%. [ F

3 ] For instance, the pulse is on for 250 msec and off

for 250 msec. The benet of the new power modulation

software is that the duty cycle can be changed. For ex-

ample, we may select a duty cycle of 20%, which results

in 100 msec on and 400 msec off, giving a ratio of

20:80. [ F 4 ] We can then harness the benets of a

lower duty cycle which results in longer cooling time for

the phaco needle, thus decreasing the amount of phaco

energy delivered to the eye. In addition, during the ex-

tended off time, no energy is delivered and nuclear

fragments can be easily aspirated.

When do we want higher or lower duty cycles? The

answer depends on the phase of surgery. For sculpting

the nucleus, such as with the technique of divide-and-

conquer, we need to deliver sufcient energy to be able

to cut the grooves. This requires a duty cycle of about

40-60%. Once we have the grooves placed in the nucle-

us and we have cracked it into quadrants, we can use a

lower duty cycle during the phaco-assisted aspiration of

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the quadrants. For this quadrant removal, a lower duty

cycle of 20-40% can be used since the principal force for

nucleus removal is the uidics and not the ultrasound.

Using the variable duty cycle programming allows the

surgeon to deliver just the right amount of ultrasound

energy during each phase of surgery. The concept to re-

member is that a higher duty cycle results in better cut-

ting power but increased heat generation and more ener-

gy-related damage to the corneal endothelium. Using the

lower duty cycle allows more uidic aspiration of nucle-

ar fragments while minimizing heat and phaco power,

resulting in clear corneas immediately after surgery. And

we all know that clear corneas on post-op day one makefor good visual acuity and very satised patients.

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13/29


lesson 09

Variable Rise TimeAnd Custom SettinskEEP In MInD tHAt tHE ULtrASOnIC PHACO POwEr IS A rEPULSIVE FOrCE:LIkE A JACk-HAMMEr, tHE PHACO nEEDLE MOVES bACk AnD FOrtH IntO tHECAtArACt At A FIxED FrEqUEnCy (bEtwEEn 28,500 tIMES/SECOnDAnD 40,000 tIMES/SECOnD, DEPEnDIng On tHE PLAtFOrM).

wEVE ALL SEEn tHIS DUrIng SUrgEry AnD OFtEn CALL It CHAttErwHEn tHE ULtrASOnIC POwEr MECHAnICALLy PUSHEStHE nUCLEUS OFF tHE PHACO tIP.

or burst width is so short that there is insufcient time

to fully ramp up each packet of phaco energy. For ex-

ample, if it takes 40 milliseconds to ramp-up the power

from zero to the preset level, but the dened burst width

is just 25 milliseconds, the desired phaco power level

will not be achieved.

SUggESTED SETTINgS FOR SURgEONS

First, remember to keep your phaco needle and all

vacuum and ow levels the same as to what you are ac-

customed. Also, no change in your surgical technique is

needed. The only thing that we will be changing is the

way that the phaco power will be delivered.

If you are accustomed to continuous phaco mode, you

will likely have an easy time starting with a hyper-pulse

mode of 60-120 pulses/second, initially at a 50% duty

cycle, and using the same maximum phaco power that

youre used to. This one simple change will likely cut

your total phaco time and energy in half with virtually

no effect on your technique.

If you are accustomed to a pulsed phaco mode, you will

have an easy time staying with about the same number

of pulses per second and keeping your maximum phaco

power the same, while decreasing your duty cycle to

25-45%. You can then implement a variable rise time in

order to further decrease the total phaco time and ener-

gy and enhance purchasing power and follow-ability.

Phaco chop surgeons will have an easier time adapt-

ing to hyper-burst mode. Keeping in mind that you will

be controlling the interval between identical bursts via

the third position, you should keep the maximum phaco

power level relatively low. You will be unable to vary

the percentage power level with your foot pedal, so set-

ting a maximum level of 10-30% is suggested. Keep

the burst width short, between 20 and 80 milliseconds,

and make sure that you use an end-point duty cycle of

50%. Depending on your machine, you may have to en-

ter this as a minimum burst interval which should be

set equal to your burst width in milliseconds to achieve

the effective end-point duty cycle of 50%.

You can further tailor your settings to better suit your

technique and your patient population, without chang-

ing your surgical technique. Transitioning to the new

phaco power modulation software is an easy way to

improve your surgical outcomes and efciency while

decreasing the heat and energy placed into the eye.

To reduce the repulsive force of phaco we can

decrease the phaco power, but this isnt always

the best answer, particularly when a nucleus is

dense and requires more phaco power for emulsica-

tion. Instead, if we initially attack the nucleus with

lower power, then hold on to it with the vacuum uid-

ics of the phaco machine, we can ramp up the power to

a higher level. The new phaco power modulation soft-

ware on most platforms allows this automatically, with

millisecond precision.

Burst and pulse modes deliver square-wave energy by

default, which means the power goes from zero to the

preset level immediately, and the resulting waveform

on the oscilloscope looks like a square. With a variable

rise time, we can have the phaco energy ramp-up over

the course of each individual pulse or burst, resulting in

a ramped wave. [ F 1, 2, 3 ]

This ramping up of the energy allows better follow-

ability of the nuclear pieces and less chatter at the phaco

tip, and it results in less energy and less heat delivered

into the eye. There are situations where it is difcult to

use a variable rise time, such as when the pulse width

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F 1

F 2 F 3

F 4


14/29


lesson 10

CreatinA Clear-CornealCataract IncisionFOr PHACOEMULSIFICAtIOn, tHE USE OF CLEAr-COrnEAL InCISIOnS HAS bECOME

VEry COMMOn FOr MAny rEASOnS: tHEy ArE EASy tO COnStrUCt,tHEy PrOVIDE gOOD ACCESS tO tHE CAtArACt, AnD tHEy SEAL wELL.

In a typical phacoemulsication, two incisions are

created: the main incision and a secondary incision,

the paracentesis. These are typically placed ap-

proximately 60 to 90 degrees apart, with the non-domi-

nant (usually left) hand at the paracentesis, while the

dominant (usually right) hand is at the main incision.

In addition, the main incision can be made at the steep

axis so as to help reduce astigmatism at this meridian.

Incisions can be made stepped or straight: a stepped inci-

sion has 2 or 3 different planes, while the straight inci-

sion has just one plane. There may be advantages with

the stepped incisions, particularly if a hinge is created.[

F 1 ]

However, all of these incisions have one thing on com-

mon: they have long tunnel lengths.[ F 2 ]

The longer tunnel lengths allow better sealing of the

incision and less induction of astigmatism, and for

these reasons, making a more square incision is rec-

ommended. The longer tunnels may have more of an

oar-lock feeling, where maneuverability within the

eye is somewhat limited, however this is usually quite

manageable.[ F 3 ]

The shorter tunnel lengths cause more astigmatic at-

tening at that meridian and they do not seal nearly as

well. While there is less oar-lock effect, the more

posterior entrance into the anterior chamber may be

prone to iris prolapse through the incision.[ F 4 ] If

there is any doubt as to the water-tightness of the inci-

sion, it is better to place a suture to close the incision.

To suture the corneal incision, 10-0 nylon or 10-0 vic-

ryl is typically used, with the knot rotated to bury it

within the corneal stroma. The suture should be placed

about half to two-thirds of corneal depth and well cen-

tered on the incision. The tension should be enough to

seal the incision well, yet not so much as to induce a

large astigmatic effect.[ F 5 ]

For managing astigmatism, keep in mind that longer

tunnels have less effect and are considered astigma-

tism-neutral, while the shorter incision cause attening

and therefore are astigmatism-inducing.[ F 6 ]

Due to the increased surface area created from a longer

tunnel length, the longer incisions tend to seal much

better. [ F 7 ]

The intra-ocular pressure at the end of the surgery ex-

erts an outward force which pushes on the inner part of

the incision and keeps the corneal layers tightly sealed.

Patients may experience some initial post-operative

hypotony, so ensuring a long tunnel length will help

prevent any incisional leakage. Phaco surgery is com-

monly referred to as sutureless, but the prudent sur-

geon knows the value of a well-placed suture when the

situation dictates. [ F 8 ]

Well-constructed clear corneal incisions are an integral

part of modern-day phacoemulsication and a tech-

nique that cataract surgeons should know.

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F 1

F 7, 8

F 2, 3, 4, 5, 6


15/29


lesson 11

If you look closely at the phaco tipat the phaco

needle itselfyou will see that it is cut at an angle,

thus giving a bevel. Most phaco needles that are

used today have a bevel to increase their utility and

usefulness during cataract surgery.

The strength of the grip is inversely related to the ne

motor control: the lighter the grip, the better the control.

If I had a stack of ten sheets of paper inte rspersed with

sheets of carbon paper, and then I asked you to write

forcefully enough so that even the bottom carbon copy

was legible, you would utilize a very strong grip. But

the quality of the writing would be very poor. On the

other hand, if I asked you to write as neatly as possible

on a single sheet of paper with your prettiest calligra-

phy writing, you would use a very ne, light grip. This

ne, light grip is best suited for the phaco probe and

for intra-ocular surgery.

The position of the hands should be at the pat ients eye

level, with both hands resting comfortably with the

shoulders relaxed. The hands can lightly rest on the

patients draped face/head or on a separate wrist-rest.

The control of the phaco probe and intra-ocular instru-

wE SPEnD MAny yEArS wrItIng AnD DEVELOPIng tHE nEUrAL PAtHwAyS FOrFInE HAnD MOtOr COntrOL bEFOrE wE EVEr PICk UP A PHACO PrObE.It IS EASIEr AnD MOrE nAtUrAL FOr MOSt PHACO SUrgEOnS tO HOLD tHE PHACOPrObE LIkE A PEn, PArtICULArLy gIVEn tHE PrObES PEn-LIkE SHAPE.

Hand Position& Pivotin

ments is primarily from the ngers and somewhat from

the wrists; gross movements of the forearms, arms,

elbows, and shoulders are not well suited for ocular

surgery.

PIVOTINg

The instruments, particularly the phaco probe, should

oat within the incision. There should be no forceful

pushing on any a spect or edge of the incision. With

any instrument, distortion of the incision can deform

the cornea and impair the view within the eye. With

the delicate balance of uidics in phacoemulsication,

distortion of the incision can lead to excessive leak-

age and an unstable chamber leading to a high risk of

capsule rupture. Finally, remember that the ultrasonic

energy from the phaco probe can produce a signi cant

amount of heat and that forcefully pushing the phaco

needle against the edge of the incision can burn the

cornea in a matter of seconds. Floating within the inci-

sion is critical.

In order to maneuver within the eye without pushing

on the incision, we need to pivot our instruments. The

action is very similar to the rowing action in a row boat:the paddle is placed within an oarlock (analogous to our

incision), and in order to push water away from us with

the paddle, we pull the handles toward us. [ F 1 ]

In the eye, when you want to move the phaco tip down-

ward, you do not push down on the incision. Rather, you

lift the back end of the phaco probe upward, which will

pivot the probe within the incision, a nd the phaco tip

will move downward. [ F 2, 3 ] This is accomplished

without deforming the incision; thus, the chamber stays

formed and the cornea remains undistorted.[ F 4 ]

KEEPINg THE EyE IN PRIMARy gAzE

With two incisions, the main incision and the para cen-

tesis, and two instruments within the eye, the patient

will not be able to move the eye even under topical

anesthesia. This two-point xation is another advan-

tage of two-handed surgery. One-handed techniques

of phacoemulsication are relatively out-dated, and, as

such, I do not teach them to my residents or students.

The surgeons best view and most maneuverable st ate

is when the eye is in primary gaze while the patient is

in the supine position. By oating in the incision, we

can keep the eye in this primar y position. Any forceful

pushing of the instruments within the eye will cause

the eye to move away from the force vectorusually

towards the medical canthus. This is dangerous since

it limits the surgeons view and maneuverability within

the eye.

Adjust your hand position so that there is no pushing

on any aspect of the incision and you will nd that the

eye will return to primary gaze. In cases of topical an-

esthesia, the patient can assist you further by looking

directly at the microscope light.

In summary, keep the hand position relaxed and com-

fortable, keep the instrument grip ne and delicate,

keep the instruments oating gently within the inci-

sion, and keep the eye in primary gaze by pivoting the

instruments.

Oar lock

Hand Control : Pivot in the incision

Pivot Action with Oars in a Rowboat

Hand Control : do NOT push down!

Lose Viscoelasticand Fluid

Very ShallowAnterior Chamber

Hand Control : PIVOT in the incision

Keeps ViscoelasticAnd Fluid in Eye

Good, DeepAnterior Chamber

Hand Control : PIVOT in the incision

PUSHING

=BAD

PIVOTING

=GOOD

Corneal Distortion

and Wrinkling

Cornea is Clear

and Undistorted

F 2, 3, 4

F 1


16/29


lesson 12

The most common bevel is a 30 degree bevel,

which means that the angle at which it is cut is

30 degrees relative to the long axis of the needle.

There are also 45 and 90 degree tips available, and other

varieties where the shaft itself may be bent or the tip may

have a are. These varieties provide different options

during nucleus removal, but I still recommend starting

with a traditional 30 degree tip during the earlier stages

of the learning.

Bevel Position;Incision SpacinIF yOU LOOk CLOSELy At tHE PHACO tIPAt tHE PHACO nEEDLE ItSELFyOU wILL SEE tHAt IS CUt At An AngLE, tHUS gIVIng A bEVEL. MOSt PHACOnEEDLES tHAt ArE USED tODAy HAVE A bEVEL tO InCrEASE tHEIr UtILIty AnDEFFICIEnCy DUrIng CAtArACt SUrgEry.

The beveled phaco needle can be positioned in a bevel-

up, bevel-sideways, or bevel-down orientation. The

bevel-up position is best suited to grooving techniques,

where the phaco needles action is similar to that of an

ice cream scoop. The goal is to only partial ly ll the tip

of the needle with nuclear material as the groove is made.

The bevel-sideways position is effective for quadrant

removal, with the opening directed towards the la rgest

part of the quadrant so that the energy is applied into the

cataractous material which would then tend to carousel

into the phaco tip. The bevel-down position is best suited

to achieving maximum grip of the nucleus.

To use a household vacuum cleaner to pick up a piece

of paper, you know that it is helpful to fully occlude the

tip in order to achieve maximum holding power. The

same is true for phacoemulsication with a peristaltic

pumpocclusion is required i n order to ach ieve the

preset maximum vacuum level and effectively hold the

nucleus. Once the nucleus is held rmly, it becomes

relatively easy to perform phaco chop or other methods

of nucleus disassembly.

The approach from a typical clear corneal incision down

towards the cataract nucleus is an angle of 30 degrees

perfectly suited for our 30 degree phaco needle in the

bevel-down position. As soon as the phaco nee dle ap-

proaches the cataract, it is very easy to achieve occlusion,

and rmly hold the nucleus in preparation for chopping.

The bevel-up position would not achieve occlusion a nd,

thus, the holding power would be weak as the vacuum

level would never reach the preset maximum with our

peristaltic pump.

By holding the phaco probe like a pen, with a light and

delicate grip, you should be able to maneuver it easily

from the bevel-down to the bevel-up position by simply

rolling the tip between your ngers.

INCISION SPACINg

In a previous lesson we explained the method of making

a proper clear corneal incision for our phaco probe. Keep

in mind that we need to act ually create two incision in

the eye: a small paracentesis of approximately 1.0mm (or

less) in width, and a main incision with a width of about

2.5-2.8mm. For ease of hand position and maximum

maneuverability within the eye, I prefer to have these

incisions about 60 degrees apart, with the main incision

for my dominant right hand and the paracentesis incision

for my left hand.

Hand Control : Bevel Up & Down

Pivot Tip with Bevel UP

Good for Sculpting / Grooving


Bevel UPOcclusion NOT AchievedPOOR grip for chopping

Bevel DOWNOcclusion IS Achieved

GOOD grip for chopping

Bevel UP - Regular

Bevel DOWN - Upside Down


30

30

Make

Paracentesis

Make

Corneal Incision

Cataract SurgeryIncisions

60

About 60 Between Incisions

ParacentesisAIM *FLAT*(plane of iris) Main Incision

AIM *UP*(plane of cornea)

The paracentesis can be made at and parallel to the iris

since it is such a small incision. While we could certainly

make it in the corneal plane to achieve a longer tunnel

length, this could limit movement of our second instru-

ment within the eye. Because the main clear corneal

incision is much wider, it becomes more important to

have a longer tunnel length, therefore it is made while

aiming up in the plane of the cornea.

Having the correct placement of the incisions and the

correct bevel positioning of the phaco probe within the

eye, can make our surgery safer and more efcient.

F 1

F 2

F 3

F 4

F 5

F 6


17/29


lesson 13

Foot Pedal ControlDurin Steps OfSurerDUrIng SUrgEry wE CLEArLy nEED PrECISE COntrOL OF bOtH HAnDS tO HOLD

InStrUMEntS AnD OPErAtE wItHIn tHE COnFInES OF tHE AntErIOr SEgMEnt.wE ALSO nEED tO COOrDInAtE FInE COntrOL OF bOtH FEEt, AS tHEy PLAy ACrUCIAL rOLE In COntrOLLIng tHE FOOt PEDALS.tHE trADItIOnAL PLACEMEnt IS tO HAVE tHE LEFt FOOt COntrOLtHE MICrOSCOPE FOOt PEDAL wHILE tHE rIgHt FOOt COntrOLStHE PHACO FOOt PEDAL.

The primary microscope controls are focus,

zoom, and centration. Additional functions in-

clude the ability to turn the microscope light

on/off as well as to adjust the brightness. The micro-

scope should be reset and centered at the beginning of

the case in order to provide a full range of adjustability.

Avoid high magnication for routine cases as this will

unnecessarily limit your eld of view.

The more important pedal during phacoemulsication

is the phaco foot-pedal as it controls the irrigation, as-

piration, as well as ultrasonic power delivery. Fine con-

trol of uidics and power can be achieved with prac-

tice. The three positions of the phaco foot-pedal are:

1-irrigation, 2-aspiration, and 3-ultrasound. Each step

is additive, so when we are in position 2, we have irri-

gation plus aspiration, and in position 3, we have irriga-

tion, aspiration, and ultrasound power delivery.

The irrigation in position 1 is either on or offthere

is no ability to titrate the amount of irrigation via the

foot-pedal. You will recall that the irrigation inow is

determined by the bottle height and the size of the inow

tubing. Taking the foot off the pedal completely is called

position zero since the phaco probe is doing nothing.

The aspiration in position 2 can be controlled in a linear

manner: the beginning of position 2 gives lower aspira-

tion and as you depress the pedal further into position

2, you get more and more aspiration. This is quite simi-

lar to the gas pedal on cars, where the acceleration is

proportional to the amount of pedal depression.

Position 3 also has the ability for linear control, where-

by progressively greater depression of the pedal gives

more phaco energy. Depending on the type of phaco

power modulation used, the foot pedal depression in

position 3 will give more ultrasound energy. In both

phaco continuous and phaco pulse mode, further de-

pression increases stroke length of the phaco needle.In phaco burst mode, further depression increases the

number of bursts per second by limiting the rest inter-

val between bursts.

FOOT-PEDAL POSITION

DURINg STEPS OF SURgERy

Before entering the eye with the phaco probe, the foot-

pedal should be in position 1 so that the irrigation uid

will prevent the eye from collapsing as the main inci-

sion is opened and the phaco needle is introduced into

the eye. A soft nucleus may be removed with simple

aspiration in position 2; however, any cataract with

signicant nuclear density will require ultrasound en-

ergy. To emulsify the cataract, the phaco probe should

deliver energy during the forward stroke. Then when

retracting the phaco probe, there is no need to deliver

energy, so we can go back to position 2 for aspiration,

or even position 1 for simple irrigation only.

Once we have a nuclear fragment or piece, we can use

aspiration in foot position 2 to bring the piece to the

tip in preparation for emulsication. Once the cataract

piece is right at the phaco tip, application of ultrasound

energy in position 3 will emulsify it.

The goal of modern cataract surgery is ultrasound-as-

sisted aspiration of the lens, where the primary means

of lens removal is aspiration, and ultrasound phaco en-

ergy is only given to assist. This will allow us to mini-

mize the amount of energy that is placed into the eye

and will result in better outcomes. Accurate foot pedal

control requires patience to master, but once learned,

it allows an increased margin of safety and efciency

during phacoemulsication.

Phaco Foot Pedal Function

Irrigation = 1

Aspiration = 2

Ultrasound = 3

Ultrasound on Forward Stroke

Ultrasound = 3

Before Entering the Eye

Irrigation = 1

Only Aspiration on Backstroke

Aspiration = 2

Aspiration to bring cataract to phaco tip

Aspiration = 2

Ultrasound when cataract is at phaco tip

Ultrasound = 3

F 1

F 2, 3, 4, 5, 6


18/29


19/29


lesson 15

CapsulorhexisCreationDECADES AgO, tHE MEtHOD FOr CAtArACt SUrgEry wAS IntrA-CAPSULArExtrACtIOn, wHErE tHE EntIrE CAtArACt AnD ItS CAPSULE wHErE rEMOVEDFrOM tHE EyE. OUr tECHnIqUE HAS ADVAnCED DrAMAtICALLy, AnD nOw MOrEtHAn 99% OF tHE tIME wE rEMOVE JUSt tHE CAtArACtOUS MAtErIAL,

wHILE LEAVIng tHE CAPSULE AnD zOnULAr StrUCtUrES IntACt.HEnCE tHE nAME ExtrA-CAPSULAr ExtrACtIOn.

The evolution of capsulorhexis began with the

use of a needle to make multiple punctures in

the anterior lens capsule to create an opening

through which to access the cataract nucleus. While

this works, it makes for an unstable capsular bag and

predisposes to a higher complication rate. Today, our

preferred method is creation of the continuous curvilin-

ear capsulorhexis (CCC).

For most cases, our ideal capsulorhexis is a well-cen-

tered, round opening of the anterior capsule with a di-

ameter of about 5mm. This allows sufcient access to

the nuclear material, and at the end of the case it al-

lows secure placement of a standard posterior chamber

IOL within the capsular bag. The typical IOL has an

optic diameter of 6mm and our 5mm capsulorhexis is

therefore able to cover the edge of the optic and hold it

securely in position after the completion of surgery.

It is important to keep the anterior chamber well

formed and the anterior lens capsule attened during

the creation of capsulorhexis. This allows for greater

control and prevents run-off and radicalization of the

capsulorhexis and allows for more control. The two

keys to achieving this stable AC and at capsule are:

use a good cohesive viscoelastic and oat within the

incision. These measures prevents collapse of the an-

terior chamber. You will remember from previous les-

sons the importance of oating within the incision, not

distorting the eye, and pivoting the instruments.

STEP 1 To start the capsulorhexis, a single puncture

is made in the central part of the anterior lens capsule.

This can be done using a bent needle, called a cysto-

tome, or by using the tips of the capsulorhexis forceps.

My capsulorhexis forceps are marked with two lines, at

2.5mm and at 5mm, to facilitate creation of a capsu-

lorhexis with an exact 5mm diameter every time. When

the sharp tips of the forceps are poked into the center

of the anterior lens capsule, the 2.5mm mark delineates

the radius of our intended capsulorhexis.

STEP 2 To propagate the tearing of the capsulorhex-

is, it is important to keep the torn capsule folded over

as this allows the tear to proceed in a more controlled

manner. I recommend understanding the force vectors

required for capsulorhexis creation by practicing using

your ngers to tear large 10cm circles in newspaper.

This will highlight the importance of keeping the torn

capsule folded over.

STEP 3 As we proceed to tear the circular capsu-

lorhexis, we will notice that half way through the

rhexis, the 2.5mm hash mark of the forceps tip should

be in the exact center of the anterior capsule, and the

5mm hash mark should be at the outer edge of the cap-

sulorhexis. This ensures that we are tearing the proper

size capsulorhexis.

STEP 4 We complete the capsulorhexis using the same

technique, and the torn central remnant is removed

from the eye and discarded. If capsulorhexis radializes,

it is important to stop, inject more cohesive viscoelas-

tic, and try to bring it centrally once again. If it extends

too far radial and out to the zonules, you may not be

able to retrieve it, and in this case you can nish by go-

ing in the opposite direction with the capsulorhexis, or

by using the bent needle cystotome to place a series of

punctures in the intended areas.

Because it is a complete circle, the capsulorhexis pro-

vides a high degree of strength and stability to the cap-

sular bag and keeps the IOL secured centrally. This

assures a consistent post-operative refractive outcome

and happy patients.

Float within the Incision

Do not allow the anterior chamber

to shallow or collapse.

Step 1Dashed line isthe intendedCapsulohexisSize of 5.0 mm

Poke sharp tips of forceps

into the center of the

anterior lens capsule.The

first hash mark (2.5mm)

represents the radius of your

intended 5.0mm

capsulorhexis.

Step 2

Start the capsulorhexis,

keeping in mind the intial

position of the first (2.5mm)

hash mark as a guide.

Step 3

Half way through the

rhexis,the 2.5mm hash

mark should be in the

exact center,and the

5.0mm hash mark should

be at the outer edge ofyour capsulorhexis.

Step 4

End of the procedure - now

the capsulohexis has the

ideal 5.0mm diameter for

cataract surgery.

F 2, 3, 4, 5

F 1


20/29


lesson 16

Hdrodissection andHdrodelineationOnCE tHE CAPSULOrHExIS HAS bEEn CrEAtED, It IS HELPFUL tO USE bALAnCEDSALt SOLUtIOn tO LOOSEn AnD SEPArAtE tHE CAtArACt In OrDEr tO FACILItAtEItS rEMOVAL. tHE twO PrIMAry tECHnIqUES ArE HyDrODISSECtIOn AnDHyDrODELInEAtIOn, bOtH OF wHICH ArE PErFOrMED USIng A bLUnt 27 gAUgE

CAnnULA On A 3CC SyrIngE FILLED wItH bALAnCED SALt SOLUtIOn.

Hydrodissection is performed between the cap-

sule and the cataract cortex in order to free

the adhesions of the cataract from the cap-

sular bag and allow it to rotate fully. Care is taken to

place the blunt ca nnula under the edge of the anterior

capsulorhexis and directed toward the lens equator.

You should stop shy of the lens equator as you do not

want to puncture the lens capsule or damage the zon-

ules. Keep the cannula steady so that it forms a tight

seal between the capsule edge and the cataract. If you

move too much and loosen this seal, the uid will re-

ux back along the path of the cannula rather than dis-

secting forward.

Next, gently press on the plunger of the syringe in order

to send the balanced salt solution around the posterior

aspect of the cataract. You want to see at least one uid

wave propagated around the cataract, and more waves

are better. As the waves propagate, they will loosen the

cataract from the capsular bag and some uid may be-

come trapped between the lens and the posterior cap-

sule. To release this uid, use the cannula to gently tap

on the center of the nucleus and the uid will be pushed

anteriorly. The key here is to be gentle so that no undue

force is used as this could cause the capsule to rupture

and the nucleus to sublux into the vitreous.

How much force is used? Very little, since the key is

slow and steady. To give you an idea of the force re-

quired, if you take the 3cc syringe with the 27-gauge

cannula and inject it outside of the eye, it would form

a gentle arc of uid that would extend only a few

inches. If your application of force causes the uid to

shoot across the room, you are being much too force-

ful. This requires a steady hand and a good sense of

uid control.

Hydrodelineation is employed by some surgeons to

separate the endo-nucleus from the epi-nucleus. The

central endo-nucleus is of a higher density and re-

quires more ultrasound energy to remove, while the

epi-nuclear shell is softer and easier to remove. This

is an optional step that is performed with the idea that

the epi-nuclear shell can act to protect the posterior

capsule during phacoemulsication of the endo-nu-

cleus. Many surgeons do not perform this step, and

instead prefer to remove the entire nucleus without

separating it into these layers.

To prevent the uid from the cannula from going be-

tween the capsule and the nucleus during hydrodelin-

eation (which was already accomplished during hy-

drodissection), the tip of the cannula should be placed

central relative to the edge of the capsulorhexis and

not beyond it. Dig the tip of the cannula into the nu-

clear material while keeping it within the connes of

the 5mm capsulorhexis. This will allow proper hydro-

delineation, and a successful uid wave will result in

the golden ring appearance at the area of separation

between the epi-nucleus and the endo-nucl eus.

Once the cataract has been freed from the capsule

with hydrodissection and split into endo-nuclear and

epi-nuclear sections with hydrodelineation, we are

ready to perform nucleus removal using aspiration

and ultrasound energy from the phaco probe.

Create a tight seal

With a tight seal,

the fluid should create

a forward fluid wave.

Hydro - dissectionBetween the Capsule

and the Cortex

Hydro - delineationBetween the Nucleus

and the Epi-nucleus / Cortex

F 1

F 2 F 3


21/29


lesson 17

Concepts OfNucleus RemovaltHE ULtrASOnIC PHACO PrObE IS USED FOr JUSt A SIngLE PArt OF tHE SUrgEry:rEMOVAL OF tHE CAtArACt nUCLEUS. tHE rESt OF tHE PrOCEDUrE CAn bEPErFOrMED wItH MUCH SIMPLEr InStrUMEntAtIOn.bUt tHESE OtHEr StEPS OF tHE SUrgEry ArE CrItICAL,

AnD wItHOUt PErFOrMIng tHEM COrrECtLy, tHE tASk OF nUCLEUSrEMOVAL bECOMES qUItE DIFFICULt.

Cataract surgery is a delicate pyramid, where

each previous step provides the foundation

upon which the next step is performed. When

everything goes well, the result is a beautiful surgery,

an excellent visual outcome, and a very happy patient.

The cataract surgery success pyramid starts with good

patient selection, good anesthesia, good exposure and

draping of the eye, and good preparation by the sur-

geon. Our next level is making proper incisions of the

right size in order to keep the anterior chamber deep

and inated during surgery. With a well-formed ante-

rior chamber, a round, well-centered capsulorhexis can

be created with minimal stress to the zonules. This al-

lows for efcient nucleus and cortex removal and IOL

insertion. These incisions will then seal very well and

will be astigmatically neutral. With all of this together,

we end up with good vision and a happy patient.

The cataract surgery complication pyramid is not so

pretty and not so happy. If we st art with poor patient

selection, ineffective anesthesia, and inadequate ex-

posure of the surgical eld, we will run into problems.

These can be issues such as an improperly constructed

incision that leaks during surgery and causes anterior

chamber instability and attening. This makes the

capsulorhexis difcult and irregular with stress placed

on the zonules. We are then at much higher risk of a

broken capsule and vitreous loss. Then vitreous gets

trapped in the patients leaky incision. The patient de-

velops cystoid macular edema and a vision of 20/200

or worse. Both the patient and the surgeon are disap-

pointed.

Clearly, its important to make sure we are building

a cataract surgery success pyramid. Since most sur-

geons who read this lesson will already have signi-

cant experience with patient selection, anesthesia, and

draping of the surgical eld, we can focus our teach-

ings on concepts of nucleus removal.

The primary concept to remember is that we are per-

forming ultrasound-assisted aspiration of the cataract.

The phaco energy

Documents

Devgan. Phaco Fundamentals. Book