Devgan Phaco Fundamentals B.-1

phaco fundamentals • �

Supported by an unrestricted educational grant from Bausch & Lomb

CME SERIES

phaco fundamentalsFor The Beginning Phaco Surgeon

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� • WoRld RepoRt cme seRIes phaco fundamentals • �

Phaco Fundamentals 1.0 An exploration of the basics of safe, technically advanced cataract extraction

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Uday Devgan, MD, FACSUday Devgan, MD, FACS is a cataract and refractive surgeon at the Maloney Vision Institute, the premier private ophthalmic practice in Los Angeles, California. He performs the full spectrum of corneal and lenticular refractive and restorative surgery and has instructed thousands of surgeons in 30 countries. Dr Devgan is Chief of Ophthalmology at Olive View UCLA Medical Center and Associate Clinical Professor at the Jules Stein Eye Institute at the UCLA School of

Medicine in Los Angeles, where he is the only faculty member to have earned the prestigious teaching award twice. Dr Devgan writes monthly columns in multiple ophthalmic journals worldwide and is a consultant for many major ophthalmic companies. He can be reached at www.UdayDevgan.com for further information.

1. The Basic Phaco Machine

2. Concepts of Fluidics

3. Flow Balance & Tubing Compliance

4. Optimizing Phaco Fluidic Settings

5. Fundamentals of Ultrasonic Phaco Power

6. Continuous, Pulse, And Burst Phaco Modes

7. Hyper Settings

8. Variable Duty Cycle

9. Variable Rise Time And Custom Settings

10. Creating A Clear-Corneal Cataract Incision

11. Hand Position & Pivoting

12. Bevel Position; Incision Spacing

13. Foot Pedal Control During Steps Of Surgery

14. Viscoelastics: Dispersive & Cohesive

15. Capsulorhexis Creation

16. Hydrodissection and Hydrodelineation

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 & Dressings

24. Post-op Medications & Follow-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 eye’s crystalline lens to the point of opaqueness, robbing the patient of sight. Medicine’s ef-forts to slow or halt this progression have failed. Yet—as was obvious even to the ancient Indian surgeon Sushruta—the 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 obstacle—the no-longer-crystalline lens. Sushruta’s 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 wasn’t until the second half of the 20th century that surgeons, empowered by micros-copy and precision implements, finally 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. It’s hard to believe today that ICCE was the state of the art as recently as 1980. Sir Harold Ridley’s observation

that World War II aviators could tolerate shards of aircraft canopy glass in their eyes prompted him to use that material—actually polymethylmethacrylate, or PMMA—to fashion the first intraocular lenses. Ridley’s innovation inspired surgeons to remove the

opaque lens while leaving intact the capsular bag as a receptacle to hold his IOLs, and extracapsular cata-ract extraction was born. ECCE’s 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. It’s a nifty trick that remains in many eye surgeons’ repertoires, and a staple of most residency train-ing programs. Refinement 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 world’s 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 phacoemulsification. Inci-sions have been shrinking ever since, with advances

the machine age saw attemPts to extricate the lens via incision, but it wasn’t until the second halF oF

the 20th century that surgeons, emPowered

by microscoPy and Precision imPlements, Finally succeeded at cataract extraction.

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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 & Lomb’s 1.8mm Stel-laris™ platform and its Akreos™ MI60 foldable intraocular lens.

While phacoemulsification has become the prevail-ing standard in the industrialized world, where cata-ract usually is treated in its early stages before the patient’s 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 surgery—a 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 figure 1. The good news is that advanced surgical skills are spreading in both countries. Surgeons are moving rapidly toward phacoemulsification as more and more patients, in-creasingly aware of the benefits of early interven-tion, are expecting their ophthalmologists to use the latest technologies.

But what exactly is phacoemulsification? While it’s easy to conceptualize, it’s actually one of the most complex forms of microsurgery—involving simul-taneous machine-controlled irrigation and aspiration to maintain anterior chamber stability, even while the ultrasound tip manipulates and blasts away at the nucleus. There’s 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 first syndi-cated in Ophthalmology World Report, is to establish a foundation of knowledge about all aspects of the phacoemulsification 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 experience—and a strong hunger for knowledge and surgical oppor-tunity. In India, only about 14% of respondents de-scribed their phaco skills as advanced, while 80% placed themselves in the basic or intermediate cat-egory. See figure 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 reasons—anterior chamber stability, low rates of induced astigmatism, lower rates of infection and other complications—as 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 figure 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 difficulty, but they also presented a long list of ideas for further study—suggestions that editors are using

to design the next cycle, which we are calling Pha-co Fundamentals 2.0. We’re 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 ParkerEditorial 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 SKILLS

Sample size: 1060

Figure 1 Figure 2 Figure 3

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My hoSpItAL focuSES on cat-aract, so I’m particularly excited about receiving the consolidat-

ed edition of “phaco fundamentals”. I really appreciate the cataract-related content of your magazine. your strong editorial focus on practi-cality is really helpful for me in my work. I hope to see more articles about the management of post-cataract complications and difficult cases as well as the perspectives and experiences of experts from other hospitals, which can inform my own practice. I also appreciate your report-ing about various hospital management mod-els and approaches, and hope to see more…

wang Peng, xian central hospital, xian First railway bureau, shaanxi province

I AM A REguLAR REAdER of World Report and find it very informative in all aspects. the series by dr.uday

devgan has been a wonderful guide for a bud-ding surgeon like me. I would like to have the booklet of the complete series of the “phaco fundamentals” so that I can preseve it for a lifetime…

maithili Kulkarni, gandhinagar, nagpur, maharashtra

WIth A popuLAtIon of 1.3 bil-lion, china has millions of peo-ple with cataract. phacoemulsi-

fication is reaching just the tip of the iceberg, and the scope for development is vast. phaco needs to be widely promoted and organized...

Zhang xinkang, dawn hospital, yancheng, Jiangsu Province

ophthALMoLogy World Report has earned the admiration of many readers for its excellent reports,

speedy dissemination of knowledge and qual-ity printing. It’s essential ready for me, and I re-ally appreciate it. compared to (its predecessor) ophthalmology times, ophthalmology World Report is even more useful and authoritative. It publishes the latest information about surgical technique as well as the latest medical equip-ment. Surgery requires both technical skills and advanced equipment, and the “phaco funda-mentals” series integrates both, giving valuable insight into actual phaco operations….

he haining, yan’an city hospital, shaanxi province

I’M An ophthALMoLogISt and a loyal reader. I’ve spent 20 years at the grassroots, pioneering phaco surgery

for cataract, and find the magazine to be very helpful. I save every issue of World Report as a reference, but my set is incomplete so I really hope to receive the collected issue of “phaco fundamentals”....

lü Jinyu, miyun county central hospital, beijing

It’S IndEEd a fantastic effort on your part to come out with a very simplified yet comprehensive series on phaco

fundamentals, which is very useful for residents like me…

geetha madhavan, sri ramachandra university, chennai

ophthALMoLogy World Report carries a lot of cataract coverage and the “phaco fundamentals”

series is really good. I’d like to see such se-rial coverage of other topics too. I especially like reading your Cover Story profiles, which introduce practitioners’ work and career de-velopment. your reporting on both surgery and therapies is so useful that I can put it directly into practice, which is excellent…

Zhang ximei, shanxi Provincial eye hospital

I AM vERy Much impressed by dr. uday devgan’s “phaco fundamen-tals” series. I wish to have the full se-

ries in the collected form. I wish to thank you and Bausch & Lomb for offering the booklet covering all 24 lessons at no charge…

s. muthuramalingam, madurai, tamil nadu

ophthALMoLogy World Report has become an important win-dow through which I learn about

new clinical techniques, advances and ideas. It is extremely helpful. My department is only now embracing phacoemulsification. For a rel-atively inexperienced doctor like me, I’m keen to obtain an elementary knowledge of phaco through your magazine and hope you can pro-vide audio/visual discs and other training ma-terials. ten thousand thanks!

Zhou Jian, yicheng hospital, anqing city, anhui Province

I’M ARdEntLy AWAItIng my copy of “phaco fundamentals” I hope your magazine can organize more of this

type of training, which is extremely useful for us on the front lines of clinical practice…

xie lianyong, mentougou district hospital, beijing

MAny thAnkS for the phaco fundamentals series, from which I have profited deeply.

My hospital doesn’t yet have phacoemulsifica-tion, but I can learn all about phaco through your magazine. this way, if conditions permit we’ll definitely purchase a system. I hope you can extend the the series to make it even more splendid…

chen yanli, weian sight restoration hospital, hebei Province

phAcoEMuLSIfIcAtIon has yet to penetrate most county level hopsitals, so grassroots practitio-

ners like me really need resources like phaco fundamentals to shore up our learning. please continue to publish this kind of series….

niu lihe, she county First People’s hospital, handan, hebei Province

pLEASE AcknoWLEdgE my re-quest for the complete series of “phaco fundamentals”. It is a fan-

tastic series for phacoemulsification beginners like me…

Junaid s wani, smhs and associated hospitals of government medical college, srinagar

I hAvE gonE thRough the “phaco fundamentals” lesson series and found it very useful…

Jalpa vashi, bw lions eye hospital, bangalore

readers’ lettersmore than 4,100 world report readers requested this Phaco Fundamentals compilation, and many told us why. here is a sampling of reader views about the 24-part series.

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The Basic Phaco MachineALL PHACO PLAtFOrMS SHArE tHE SAME bASIC StrUCtUrE AnD COnCEPtS. tHE PHACO MACHInE AIMS tO bALAnCE FLUIDICS wItHIn tHE EyE, wHILE DELIVErIng ULtrASOnIC EnErgy AnD VACUUM In OrDEr tO EMULSIFy AnD ASPIrAtE tHE CAtArACt tHrOUgH A SMALL InCISIOn.

ally works by depressing it towards the floor 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). [ Figure 1 illustrates additive pedal functions. ]

FOOT POSITION 1: IRRIgATIONIt’s important to realize that during phacoemulsifica-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 complications.

The irrigation function of the phaco machine is meant to provide a source of fluid 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 infusion—the infusion is either turned on or turned off.

The height of the infusion bottle determines the rela-tive infusion pressure and flow rate during the sur-gery. To keep the eye inflated during surgery, we need to ensure that the fluid inflow rate is greater than the fluid outflow rate. [ Figure 2: Irrigation of fluid into the eye is the function of phaco foot

position 1. ]

lesson 01Figures 2,3,4

FOOT POSITION 2: VACUUM / ASPIRATION OF FLUIDPhaco foot position 2 is the control of the relative aspira-tion and vacuum level of the fluid from the eye. There is a linear control of vacuum and flow, so that the top of foot position 2 provides less vacuum or flow than the middle or bottom range of the same foot position 2. This is similar to the gas pedal in a car, where the car’s throttle is opened more as the gas pedal is further depressed. To create the vacuum and the aspiration flow of fluid, the phaco machine must have a fluid pump. The most com-mon types of fluid pumps are peristaltic and venturi, and these will be explained fully in future columns.

The vacuum and aspiration levels that are created draw the fluid out of the eye and into a waste fluid collec-tion via the outflow 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 fluid outflow during phaco-emulsification: the outflow from the phaco probe cre-ated by the fluid pump, and the leakage of fluid from the incisions. [ Figure 3: Vacuum and aspiration of fluid from the eye is

the function of phaco foot position 1. ]

FOOT POSITION 3: ULTRASOUND ENERgyThe 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 fluid into the eye, (2) the outflow tubing that removes the fluid via flow that is created by the phaco machine’s fluid 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. [ Figure 4: Foot pedal position 3 controls the delivery of the ultrasound

energy into the eye. ]

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 control the phaco ma-chine during cataract surgery. This foot pedal tradition-

Figure 1

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

phaco fluidics is to keep the inflow greater than the out-flow. [ Figure 1: Keep inflow greater than outflow to ensure stability

of the eye during surgery. ]

MODULATINg PHACO FLUID FLOw: POISEUILLE’S EQUATIONThe basic equation that governs all fluid flow during phacoemulsification surgery is Poiseuille’s Equation:F = ΔP π r � / � η L

In this equation, F = flow, ΔP = pressure gradient, r = radius of the tube, η = viscosity of fluid, 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 fluid 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 ~ ΔP 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 flow. This is clearly illustrated in a common sense situation of drinking with straws. [ Figure 2: Poiseuille’s equation shows

that smaller bore tubing (a) requires higher vacuum and results in a

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

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

tially related to the radius of the tubing. ]

MODULATINg FLUID INFLOwThe source of fluid inflow is the bottle of balanced salt solution that is hanging on the phaco machine. The two factors that determine the rate of inflow are: the change in pressure and the radius of the inflow tubing.

The change in pressure, can be modulated by raising or lowering the height of the bottle relative to the pa-tient’s eye: the higher the bottle, the higher the infusion pressure. The inflow tubing has a large radius in order to maximize the flow and make sure that we keep our inflow greater than the outflow. 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 inflow can be

modulated by changing the bottle height and therefore the pressure

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

MODULATINg FLUID OUTFLOwFor fluid outflow, there are two sources of fluid leav-ing the eye: (1) the fluid that is removed via the phaco probe as a result of the vacuum level generated by the fluid pump, and (2) fluid leakage from the incisions.

The rate of the fluid outflow 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 machine’s fluid pump. The rate of the fluid outflow loss via the incisions depends on their size and the relative fit of the instruments within these incisions.

Some degree of fluid 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 phacoemulsification. With the use of advanced phaco power modulations, more ex-perienced phaco surgeons tend to move towards tighter incisions which can give more stable fluidics.

The composition, nature, and size of the inflow and outflow tubing are different.

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Figure 3

Figure 1

Figure 2

The basic concept of fluidics is that the inflow of fluid must be greater than the outflow of fluid. By keep a constant infusion pressure and limit-

ing the outflow, we can ensure that the eye stays in-flated and stable during surgery. If we allow the outflow to exceed the fluid inflow, even for just a fraction of a second, we experience surge within the eye and this can cause chamber instability, collapse of the eye, and aspiration of the posterior capsule. The primary rule for

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lesson 03

Flow Balance & Tubing ComplianceSUrgE IS tHE SItUAtIOn wHEn tHE OUtFLOw OF FLUID FrOM tHE EyE ExCEEDS tHE InFLOw, EVEn FOr JUSt A FrACtIOn OF A SECOnD. wHEn tHIS OCCUrS, tHE CHAMbEr tEnDS tO COLLAPSE AnD tHE POStErIOr CAPSULE CAn bE SUCkED IntO tHE PHACO PrObE In An InStAnt, rESULtIng In A rUPtUrED POStErIOr CAPSULE AnD VItrEOUS LOSS.

In order to maintain this flow balance, where the inflow is always greater than the outflow, we can use different sized tubing. If we look at the inflow

tubing we notice that it is significantly different than the outflow tubing.

Figure 1: Comparison of Inflow and Outflow Phaco Tubing.Figure 2: compliant tubing can collapse and cause surge during cataract surgery.Figure 3: Flow rate varies exponentially with the size of the phaco needle radius/diameter.Figure 4: a small change in the needle size can result in a large decrease in the flow rate.

INFLOw VS. OUTFLOw TUBINgThe inflow tubing is large bore with walls that are thin, and the tubing is very flexible. The purpose of this tub-ing is to provide a high flow of fluid under low pressure situations. The maximum pressure achieved within this inflow tubing is determined by the height of the infu-sion bottle, and this level is not very high.

The outflow tubing is smaller bore with thick walls, and the tubing is very rigid and relatively non-compliant. Because the flow varies exponentially with the radius of the tubing, the smaller bore outflow tubing can help ensure that the outflow is less than the inflow. The out-flow tubing has rigid, thick walls in order for it to have a low compliance which helps to prevent surge. The maximum pressure achieved within the outflow tubing is determined by the fluid pump of the phaco machine and can easily exceed 500 millimeters of mercury.

This high vacuum level can cause collapse of the out-flow tubing if its walls are too thin and of high com-pliance. When the outflow tubing collapses, and then rebounds back to its normal state after the vacuum lev-el drops, this energy release causes an immediate and dangerous surge of fluid out of the eye. This collapse

of tubing due to high vacuum levels occurs most com-monly during occlusion of the phaco probe, and then once the occlusion breaks, the tubing rebounds and the surge occurs. This is called post-occlusion surge and is one of the main causes of posterior capsule rupture during cataract surgery.

PHACO NEEDLE SIzINgThe size of the phaco needle is important for phaco fluidics because it affects the outflow rate. The impor-tant thing to remember from Poiseuille’s Equation is that the flow is proportional to the radius of the tube to the fourth power. This means that a small change in the size of the phaco needle can result in a very large change in the flow. Comparing two common size pha-co needles, 0.9mm versus 1.1mm, with all other fac-tors equal it is surprising to see that the flow through the larger 1.1mm needle is more than twice that of the 0.9mm needle. As the needle size decreases, the flow drops exponentially.

If we switch from a 1.1mm phaco needle to a 0.9mm needle, with all other phaco parameters unchanged, the relative flow will decrease by more than half—to 45% of the relative flow through the 1.1mm needle. In order to achieve the same flow while decreasing the needle size, a very substantial increase in the pressure gradient is required.

Once we determine the proper tubing size and phaco needle size for our needs, we can then select the other parameters of the phaco machine. Remember that the tubing size and phaco needle size are explicit variables that play an important role in the fluidics.

In our next lesson we will explain the variables that are adjustable on the phaco machine: bottle height, vacuum level, and aspiration flow rate. We’ll also examine the two primary types of fluid pumps that are used in phaco machines: peristaltic and venturi.

Figure 1

Figures 2, 3, 4

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Optimizing Phaco Fluidic SettingstHE CHALLEngE OF CAtArACt SUrgEry ArISES In LArgE PArt FrOM tHE SMALL COnFInES OF tHE wOrkIng SPACE. tHE AntErIOr AnD POStErIOr CHAMbEr COMbInED tyPICALLy COMPrISE LESS tHAn 1 CUbIC CEntIMEtEr OF SPACE AnD PrOVIDE VEry LIttLE rOOM FOr ErrOr. tHE FUnCtIOn OF tHE PHACO FLUIDICS IS tO bALAnCE tHE InFLOw AnD OUtFLOw OF FLUID In OrDEr tO MAIntAIn tHE wOrkIng SPACE, brIng CAtArACt MAtErIAL tO tHE PHACO tIP, AnD PrEVEnt COLLAPSE OF tHE EyE. OPtIMIzIng tHE PHACO FLUIDIC SEttIngS IS InStrUMEntAL tO 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 flow 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 flow between a larger bore needle and a small bore needle varies exponentially due to Poiseuille’s Equation. In summary, the smaller bore phaco needles are suited for high-vacuum, low-flow fluidics, while the larger bore needles are better suited for high-flow, low-vacuum fluidics. 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 flow rate for a peristaltic machine is typically giv-en in cc of fluid per minute. This is determined by the rate at which the peristaltic rollers milk the fluid along

the outflow tubing. With the phaco needle unobstructed the maximum flow 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 flow rate declines and approaches zero. The flow rate determines the speed at which things happen in the eye during phacoemulsification.

The bottle height determines the inflow rate of fluid into the eye. Very much like a water-tower in a small town, the height of the fluid above the eye creates a force-ful infusion of fluid via gravity: the higher the infusion bottle, the greater the inflow pressure and inflow rate.

With an unobstructed phaco needle, the flow rate is at the maximum, but the vacuum level is very low—very 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 power—and the holding power is used to fixate

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 SETTINgSIn order to optimize the phaco fluidic settings, it is im-portant to match the parameters to the technique and the surgeon’s preference.

The first 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 significantly greater flow 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 inflow of fluid into the eye. In order to help prevent surge, it is important to keep the inflow of fluid greater than the outflow of fluid at all times. The inflow of fluid comes from only one source, the bottle of balanced salt solution, while the outflow of fluid comes from two sources, the suction via the phaco needle and the leakage from the incisions. If, at any time, the outflow out-strips in the inflow, 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 sufficient inflow of fluid, 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 benefit from increasing the bot-tle height.

For phaco chop, holding power of the nucleus is impor-tant in order to securely fixate 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 flow rate, with 20cc/min being very slow and 50cc/min be-ing very fast. The same vacuum and flow 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 fluidic 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 flow 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 flow rate of less than 30cc/min is sufficient 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 flow rate of 30-50cc/min, depending on the needle size, is typically sufficient for this purpose.

With knowledge of the concepts behind the variables, it is easy to tailor the fluidic settings to the surgeon and technique. Understanding the concepts behind the phaco fluidic settings is instrumental in optimizing the parameters for increasing the efficiency and safety of your phaco technique.

> occlusion of the phaco tip is required to achieve the preset maximum vacuum level with peristaltic systems.

lesson 04

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Fundamentals of Ultrasonic Phaco PowertHE PHACO ULtrASOUnD PrObE DELIVErS EnErgy IntO tHE EyE tHAt CAn bE USED tO brEAk UP tHE CAtArACt tO FACILItAtE EMULSIFICAtIOn AnD ASPIrAtIOn. It ACCOMPLISHES tHIS by VIbrAtIng At A FIxED FrEqUEnCy wHEn tHE FOOt-PEDAL IS DEPrESSED tO POSItIOn tHrEE. wHEn wE tItrAtE tHE AMOUnt OF ULtrASOUnD EnErgy wE PLACE IntO tHE EyE, wE ArE kEEPIng tHE FrEqUEnCy COnStAnt bUt wE ArE InCrEASIng tHE StrOkE LEngtH AnD tHErEFOrE, 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 fluid 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 fingers, 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 fingers. But it’s better to singe your fingertips than fry your patient’s 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 efficient 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 05Figure 1 Figure 2

Figure 3 Figure 4

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Continuous, Pulse, And Burst Phaco ModestHE bASIC POwEr SEttIngS ArE COntInUOUS, PULSE, AnD bUrSt. In tHE COntInUOUS POwEr SEttIng, COntInUOUS EnErgy IS DELIVErED wItH VArIAbLE POwEr DEPEnDIng On HOw LOng tHE FOOt PEDAL IS DEPrESSED. tHE MAxIMUM POwEr SEttIng CAn bE PrESEt AnD tHEn OnE HAS COntrOL OF tHE MAxIMUM AMOUnt OF PHACO POwEr DELIVErED—tHE LOngEr tHE FOOt PEDAL IS DEPrESSED, 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 defining 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 phaco probe 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 defines a specific 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 infinitely small.

Burst mode allows a true phaco-assisted aspiration of the lens nucleus. We use the vacuum and fluidics of the

Figures 2, 3, 4

Figure 1

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lesson 07

Hyper SettingstHE rAngE OF PrOgrAMMAbILIty OF tHE PULSE AnD bUrSt PHACO SEttIngS HAS ExPAnDED COnSIDErAbLy. wHILE PrEVIOUS gEnErAtIOnS OF PHACO PLAtFOrMS HAD PULSE rAtES OF UP tO 20 PULSES PEr SECOnD, tHE nEwEr gEnErAtIOn MACHInES HAVE tHE AbILIty tO DELIVEr UP tO 120 PULSES PEr SECOnD. SIMILArLy, tHE OLDEr MACHInES HAD bUrSt wIDtHS AS nArrOw AS 30 MILLISECOnDS, wHILE tHE nEw PLAtFOrMS ArE AbLE tO DELIVEr bUrSt wIDtHS AS 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. [ Figure 1 ]

The more pulses per second we can give, the smoother the power delivery will be—very 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 finely 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 finely serrated knife, yet delivers half of the energy of continuous phaco power. [ Figure 2 ]

Hyper settings in burst mode allow finer 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 finer 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 fluidic forces—the flow, aspiration, and vacuum forces. The ultrasonic power delivery is there to assist the fluidics once a denser piece of nucleus is encountered. My pre-ferred setting for phaco surgery is burst mode, with a very fine 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-emulsification, 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. [ Figures 3 and 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.

Figure 1

Figures 2, 3, 4

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LESSON 08

Variable Duty CyclewHEn wE CHOOSE A MODE SUCH AS PULSE MODE, wHICH ALtErnAtES PHACO POwEr PULSES wItH PErIODS OF rESt, tHE DEFAULt rAtIO IS 50:50. tHIS IS CALLED A 50% DUty CyCLE, AS EACH COMPLEtE CyCLE IS COMPOSED OF EnErgy 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 ULtrASOUnD EnErgy 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 significant 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. [ Figure 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 I’d 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 specific 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 result—a total cycle time of 100 milliseconds, with 10 pulses per second and a 40% duty cycle. [ Figure 2 ]

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

3 ] For instance, the pulse is “on” for 250 msec and “off” for 250 msec. The benefit 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. [ Figure 4 ] We can then harness the benefits 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 sufficient 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

Figure 2

Figures 3, 4

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 fluidics 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 fluidic 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 make for good visual acuity and very satisfied patients.

Figure 1

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lesson 09

Variable Rise Time And Custom SettingskEEP In MInD tHAt tHE ULtrASOnIC PHACO POwEr IS A rEPULSIVE FOrCE: LIkE A JACk-HAMMEr, tHE PHACO nEEDLE MOVES bACk AnD FOrtH IntO tHE CAtArACt At A FIxED FrEqUEnCy (bEtwEEn 28,500 tIMES/SECOnD AnD 40,000 tIMES/SECOnD, DEPEnDIng On tHE PLAtFOrM). wE’VE ALL SEEn tHIS DUrIng SUrgEry AnD OFtEn CALL It “CHAttEr”—wHEn tHE ULtrASOnIC POwEr MECHAnICALLy PUSHES tHE nUCLEUS OFF tHE PHACO tIP.

or burst width is so short that there is insufficient 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 defined burst width is just 25 milliseconds, the desired phaco power level will not be achieved.

SUggESTED SETTINgS FOR SURgEONSFirst, remember to keep your phaco needle and all vacuum and flow 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 you’re 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 efficiency 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 isn’t always the best answer, particularly when a nucleus is

dense and requires more phaco power for emulsifica-tion. Instead, if we initially attack the nucleus with lower power, then hold on to it with the vacuum fluid-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. [ Figures 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 difficult to use a variable rise time, such as when the pulse width

Figure 1

Figure 2 Figure 3

Figure 4

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lesson 10

Creating A Clear-Corneal Cataract 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 phacoemulsification, 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. [ Figure 1 ]

However, all of these incisions have one thing on com-mon: they have long tunnel lengths. [ Figure 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. [ Figure 3 ]

The shorter tunnel lengths cause more astigmatic flat-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. [ Figure 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. [ Figure 5 ]

For managing astigmatism, keep in mind that longer tunnels have less effect and are considered astigma-tism-neutral, while the shorter incision cause flattening and therefore are astigmatism-inducing. [ Figure 6 ]

Due to the increased surface area created from a longer tunnel length, the longer incisions tend to seal much better. [ Figure 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. [ Figure 8 ]

Well-constructed clear corneal incisions are an integral part of modern-day phacoemulsification and a tech-nique that cataract surgeons should know.

Figure 1

Figures 7, 8

Figures 2, 3, 4, 5, 6

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lesson 11

If you look closely at the phaco tip—at the phaco needle itself—you 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 fine motor control: the lighter the grip, the better the control. If I had a stack of ten sheets of paper interspersed 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 fine, light grip. This fine, light grip is best suited for the phaco probe and for intra-ocular surgery.

The position of the hands should be at the patient’s eye level, with both hands resting comfortably with the shoulders relaxed. The hands can lightly rest on the patient’s 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 FOr FInE HAnD MOtOr COntrOL bEFOrE wE EVEr PICk UP A PHACO PrObE. It IS EASIEr AnD MOrE nAtUrAL FOr MOSt PHACO SUrgEOnS tO HOLD tHE PHACO PrObE LIkE A PEn, PArtICULArLy gIVEn tHE PrObE’S PEn-LIkE SHAPE.

Hand Position & Pivoting

ments is primarily from the fingers and somewhat from the wrists; gross movements of the forearms, arms, elbows, and shoulders are not well suited for ocular surgery.

PIVOTINgThe instruments, particularly the phaco probe, should float within the incision. There should be no forceful pushing on any aspect 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 fluidics in phacoemulsification, 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 significant 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. [ Figure 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, and the phaco tip will move downward. [ Figures 2, 3 ] This is accomplished without deforming the incision; thus, the chamber stays formed and the cornea remains undistorted. [ Figure 4 ]

KEEPINg THE EyE IN PRIMARy gAzEWith two incisions, the main incision and the paracen-tesis, and two instruments within the eye, the patient will not be able to move the eye even under topical anesthesia. This two-point fixation is another advan-tage of two-handed surgery. One-handed techniques of phacoemulsification are relatively out-dated, and, as such, I do not teach them to my residents or students.

The surgeon’s best view and most maneuverable state is when the eye is in primary gaze while the patient is in the supine position. By floating in the incision, we can keep the eye in this primary position. Any forceful pushing of the instruments within the eye will cause the eye to move away from the force vector—usually towards the medical canthus. This is dangerous since it limits the surgeon’s 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 find 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 fine and delicate, keep the instruments floating gently within the inci-sion, and keep the eye in primary gaze by pivoting the instruments.

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


PUSHING=BAD

PIVOTING=GOOD

Corneal Distortionand Wrinkling

Cornea is Clearand Undistorted

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


Keeps ViscoelasticAnd Fluid in Eye

Good, DeepAnterior Chamber


PUSHING=BAD

PIVOTING=GOOD

Corneal Distortionand Wrinkling

Cornea is Clearand Undistorted

Oar lock

Hand Control : Pivot in the incision

Pivot Action with Oars in a Rowboat

Figures 2, 3, 4

Figure 1

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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 flare. 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 SpacingIF yOU LOOk CLOSELy At tHE PHACO tIP—At tHE PHACO nEEDLE ItSELF—yOU wILL SEE tHAt IS CUt At An AngLE, tHUS gIVIng A bEVEL. MOSt PHACO nEEDLES tHAt ArE USED tODAy HAVE A bEVEL tO InCrEASE tHEIr UtILIty AnD EFFICIEnCy 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 needle’s action is similar to that of an ice cream scoop. The goal is to only partially fill 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 largest 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 phacoemulsification with a peristaltic pump—occlusion is required in order to achieve the preset maximum vacuum level and effectively hold the nucleus. Once the nucleus is held firmly, 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 needle ap-proaches the cataract, it is very easy to achieve occlusion, and firmly hold the nucleus in preparation for chopping. The bevel-up position would not achieve occlusion and, 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 fingers.

INCISION SPACINgIn 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 actually 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.

Bevel UP - “Regular”

Bevel DOWN - “Upside Down”

Hand Control : Bevel Up & Down

30

30

Hand Control : Bevel Up & DownPivot Tip with Bevel UPGood for Sculpting / Grooving

Hand Control : Bevel Up & DownBevel UPOcclusion NOT AchievedPOOR grip for chopping

Bevel DOWNOcclusion IS Achieved

GOOD grip for chopping

MakeParacentesis

MakeCorneal Incision

Cataract SurgeryIncisions

60

About 60º Between Incisions

ParacentesisAIM *FLAT*(plane of iris) Main Incision

AIM *UP*(plane of cornea)




30

30





MakeParacentesis



60







30

30





MakeParacentesis



60




The paracentesis can be made flat 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 efficient.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

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lesson 13

Foot Pedal Control During Steps Of SurgeryDUrIng 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 A CrUCIAL rOLE In COntrOLLIng tHE FOOt PEDALS. tHE trADItIOnAL PLACEMEnt IS tO HAVE tHE LEFt FOOt COntrOL tHE MICrOSCOPE FOOt PEDAL wHILE tHE rIgHt FOOt COntrOLS tHE 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 magnification for routine cases as this will unnecessarily limit your field of view.

The more important pedal during phacoemulsification is the phaco foot-pedal as it controls the irrigation, as-piration, as well as ultrasonic power delivery. Fine con-trol of fluidics 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 off—there is no ability to titrate the amount of irrigation via the foot-pedal. You will recall that the irrigation inflow is determined by the bottle height and the size of the inflow 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 SURgERyBefore entering the eye with the phaco probe, the foot-pedal should be in position 1 so that the irrigation fluid 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 significant 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 emulsification. 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 efficiency during phacoemulsification.

Phaco Foot Pedal Function

Irrigation = 1

Aspiration = 2

Ultrasound = 3Ultrasound 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

Phaco Foot Pedal Function

Irrigation = 1

Aspiration = 2

Ultrasound = 3Ultrasound 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

Figure 1

Figures 2, 3, 4, 5, 6

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lesson 14

Viscoelastics: Dispersive & CohesiveVISCOELAStICS, ALSO rEFErrED tO AS OPHtHALMIC VISCOSUrgICAL DEVICES (OVDS), ArE VISCOUS SUbStAnCES tHAt ALLOw US tO MAkE PHACOEMULSIFICAtIOn EASIEr AnD SAFEr. OnCE tHE VEry FIrSt InCISIOn IS MADE, tHE EyE HAS A tEnDEnCy tO COLLAPSE AS tHE AqUEOUS LEAkS OUt. tHE LArgEr tHE InCISIOn, tHE grEAtEr tHE PrOPEnSIty FOr tHE EyE tO COLLAPSE, AnD tHE grEAtEr tHE rISk tO tHE PAtIEnt. by rEPLACIng tHE AqUEOUS wItH A tHICkEr VISCOELAStIC, wE CAn PrEVEnt tHE EyE’S COLLAPSE.

There are two main classes of viscoelastics: dis-persive and cohesive, and they behave differ-ently. Dispersive OVDs have the consistency of

syrup or molasses and they are able to flow like very thick liquids. This gives dispersive OVDs the ability to coat ocular structures quite well, and this coating is not easily washed away by the flow of balanced salt so-lution during surgery. This coating of dispersive OVD is helpful to protect the corneal endothelium from the ultrasonic waves during surgery.

Cohesive OVDs are more solid than liquid and they have the consistency of gelatin, which means that they cannot coat or flow very well. However, because they are much thicker, they are able to maintain space and pressurize the eye quite well. This is very useful to keep the anterior chamber formed, to keep the anterior

capsule flat during capsulorhexis creation, to move and manipulate iris or other tissues, and to keep the empty capsular bag open for IOL insertion. It’s important to understand that there is a spectrum of viscoelastics and that a moderate OVD may have some dispersive prop-erties as well as some cohesive properties. For many surgeons, using a moderate OVD has the best of both, and they are able to use it as their exclusive viscoelastic for the entire surgery. Other surgeons may prefer hav-ing two viscoelastics, one cohesive and one dispersive, for different stages during a single surgery.

At the beginning of surgery, when the viscoelastic is placed into the eye, the goal is to perform an exchange: inject the OVD while the aqueous is forced out of the eye. This is accomplished by placing the cannula across the anterior chamber and injecting distally, thereby

forcing the aqueous to exit from the anterior chamber through the same incision. [ Figure 1 ]

IDEAL VISCOELASTIC CHARACTERISTICS DURINg SURgERy:• Maintain AC depth during capsulorhexis creation: cohesiveTo maintain space and keep the anterior lens capsule flat, the cohesive viscoelastics are the most helpful during this step.

• Corneal endothelial protection during phacoemulsification: dispersiveBecause they have the ability to coat, the dispersive viscoelastics work very well to keep the corneal endothelium protected during phaco.

• Prevent iris prolapse during surgery: cohesiveThe ability to pressurize and maintain space is best accomplished with a cohesive. Therefore, prolapse of iris tissue usually may be prevented or treated with a cohesive viscoelastic.

• Lubricate the IOL injector system: dispersiveThe thinner dispersive OVDs can lightly coat the

IOL injector system and allow lubrication that will facilitate IOL delivery.

• Expand the empty capsular bag for IOL insertion: cohesiveAgain, to maintain space and keep the empty capsular bag open, the cohesive OVDs work very well. Avoid the super-cohesive OVDs here as they may be so solid that they can deflect the IOL as it is inserted.

At the end of surgery it is important to thoroughly re-move the viscoelastic from the eye, otherwise it can block the trabecular meshwork and the patient will ex-perience very high intra-ocular pressures after surgery. The dispersive viscoelastics can be harder to remove since they have a tendency to spread out and coat the ocular structures. The cohesive viscoelastics tend to stick together as a single mass and are therefore usually easier to fully remove.

Use of a viscoelastic can make phacoemulsification easier for the surgeon as well as safer for the patient. It is for this reason that is has become an integral part of our surgeries.

Filling The AC With Viscoelastic

Spectrum of Viscoelastics

Ability to Maintain Space & Pressure

Ability to Coat & Protect

Dispersive Moderate Cohesive Super Cohesive

More Liquid More Solid

Figure 1 Figure 2

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lesson 15

Capsulorhexis CreationDECADES AgO, tHE MEtHOD FOr CAtArACt SUrgEry wAS IntrA-CAPSULAr ExtrACtIOn, wHErE tHE EntIrE CAtArACt AnD ItS CAPSULE wHErE rEMOVED FrOM tHE EyE. OUr tECHnIqUE HAS ADVAnCED DrAMAtICALLy, AnD nOw MOrE tHAn 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 sufficient 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 flattened 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 flat capsule are: use a good cohesive viscoelastic and float within the incision. These measures prevents collapse of the an-

terior chamber. You will remember from previous les-sons the importance of floating 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 fingers 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 finish 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.

Step 1Dashed line isthe intended CapsulohexisSize 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 of your capsulorhexis.

Step 4

End of the procedure - now the capsulohexis has the ideal 5.0mm diameter for cataract surgery.

Float within the Incision

Do not allow the anterior chamberto shallow or collapse.

Step 1Dashed line isthe intended CapsulohexisSize 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 of your capsulorhexis.

Step 4

End of the procedure - now the capsulohexis has the ideal 5.0mm diameter for cataract surgery.

Float within the Incision

Do not allow the anterior chamberto shallow or collapse.

Figures 2, 3, 4, 5

Figure 1

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lesson 16

Hydrodissection and HydrodelineationOnCE tHE CAPSULOrHExIS HAS bEEn CrEAtED, It IS HELPFUL tO USE bALAnCED SALt SOLUtIOn tO LOOSEn AnD SEPArAtE tHE CAtArACt In OrDEr tO FACILItAtE ItS rEMOVAL. tHE twO PrIMAry tECHnIqUES ArE HyDrODISSECtIOn AnD HyDrODELInEAtIOn, 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 cannula 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 fluid will re-flux 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 fluid 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 fluid may be-come trapped between the lens and the posterior cap-sule. To release this fluid, use the cannula to gently tap on the center of the nucleus and the fluid 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 fluid that would extend only a few inches. If your application of force causes the fluid to shoot across the room, you are being much too force-ful. This requires a steady hand and a good sense of fluid 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 phacoemulsification 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 fluid 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 confines of the 5mm capsulorhexis. This will allow proper hydro-delineation, and a successful fluid wave will result in the “golden ring” appearance at the area of separation between the epi-nucleus and the endo-nucleus.

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.

Hydro - dissectionBetween the Capsule and the Cortex

Hydro - delineationBetween the Nucleus and the Epi-nucleus / Cortex

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

Create a tight seal

With a tight seal, the fluid should create a forward fluid wave.

Figure 1

Figure 2 Figure 3

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lesson 17

Concepts Of Nucleus 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 bE PErFOrMED wItH MUCH SIMPLEr InStrUMEntAtIOn. bUt tHESE OtHEr StEPS OF tHE SUrgEry ArE CrItICAL, AnD wItHOUt PErFOrMIng tHEM COrrECtLy, tHE tASk OF nUCLEUS rEMOVAL 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 inflated 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 efficient 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 start with poor patient selection, ineffective anesthesia, and inadequate ex-

posure of the surgical field, 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 flattening. This makes the capsulorhexis difficult 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 patient’s 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, it’s important to make sure we are building a cataract surgery success pyramid. Since most sur-geons who read this lesson will already have signifi-cant experience with patient selection, anesthesia, and draping of the surgical field, 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 should only be applied when there is actual cataract material at the tip of the phaco nee-dle. Being in foot-pedal position 3 without having the

phaco tip in cataract material will result in transmis-sion of the ultrasound energy through the aqueous and to the corneal endothelium resulting in post-operative corneal edema.

The fluidic control of the phaco machine is used to draw the cataract pieces toward the phaco tip. Re-member that in a peristaltic machine, the maximum pre-set vacuum level is not reached until the phaco tip is occluded. This is in contrast to a venturi system where the maximum pre-set vacuum can be created instantly and occlusion is not required. A common mistake novice surgeons make is trying to use ultra-sound power to draw cataract pieces to the tip, when, in fact, the ultrasound energy can be repulsive.

In order to facilitate removal of the cataract nucleus with the phaco probe, it is helpful to break the nucleus into quadrants or fragments. The techniques of nucle-us disassembly include divide-and-conquer, stop-and-chop, and quick-chop. Most surgeons start learning them in that order and eventually choose some form of phaco chop as their primary technique. In our next set of lessons, we will explore each of these methods.

Cataract Surgery Success Pyramid

20/20

Happy Patient

Well sealed neutral incisions

Efficient Nucleus/Cortex Removal

Round Capsulorhexis/No Zonule Stress

Well made incision/Deep and Maintained AC

Good Anesthesia/Good Exposure/Prior Preparation

20/200

Chronic CME

Vitreous to the leaky wound

Broken Capsule and Vitreous Loss

Radialized Capsulorhexis/Broken Zonules

Short Leaky Incision and a Flat Anterior Chamber

Ineffective Block/Poor Exposure/Poor Patient Selection

Cataract Surgery Complication Pyramid

Apply ultrasound energy when the nuclear pieces are at the tip.

Cataract Surgery Success Pyramid

20/20

Happy Patient

Well sealed neutral incisions

Efficient Nucleus/Cortex Removal

Round Capsulorhexis/No Zonule Stress

Well made incision/Deep and Maintained AC

Good Anesthesia/Good Exposure/Prior Preparation

20/200

Chronic CME

Vitreous to the leaky wound

Broken Capsule and Vitreous Loss

Radialized Capsulorhexis/Broken Zonules

Short Leaky Incision and a Flat Anterior Chamber

Ineffective Block/Poor Exposure/Poor Patient Selection

Cataract Surgery Complication Pyramid

Apply ultrasound energy when the nuclear pieces are at the tip.

Figure 1

Figure 2 Figure 3

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lesson 18

Divide-and-Conquer Technique of Nucleus RemovaltO FACILItAtE rEMOVAL OF tHE CAtArACt nUCLEUS wItH tHE PHACO PrObE, It IS HELPFUL tO DIVIDE It IntO qUADrAntS Or SEgMEntS, wHICH ArE MOrE EASILy ExtrACtED. tHE trADItIOnAL MEtHOD OF ‘OnE-HAnDED’ PHACO InVOLVES USIng tHE ULtrASOUnD EnErgy tO bOwL OUt tHE nUCLEUS. HOwEVEr, tHIS rEqUIrES A LOt OF EnErgy AnD IS rAtHEr SLOw AnD CUMbErSOME. USIng A MEtHOD tO MECHAnICALLy DISASSEMbLE tHE nUCLEUS ALLOwS FOr EASIEr rEMOVAL.

A simple and effective approach to nucleus re-moval is the divide-and-conquer technique, in which the phaco probe is first used to sculpt

grooves into the nucleus, and then a second instrument is used to crack the nucleus into pieces, which can then be easily removed.

To create the groove, the phaco settings should be op-timized for sculpting. Use a high pulse rate of between 60 and 120 pulses per second, a duty cycle of 50% or more, and a maximum power setting of 20-60% de-pending on the density of the nucleus. If your phaco machine does not have the ability to do a high pulse rate and a variable duty cycle, then it is acceptable to use continuous phaco energy. Be aware that the con-tinuous phaco energy mode will put more energy into the eye and may lead to a high rate of corneal endothe-lial cell loss. For fluidics, the goal is to simply keep the anterior chamber deep and well formed while provid-ing a small amount of flow and vacuum to aspirate the sculpted cataract material.

Start the groove as close to the sub-incisional area as possible so that the groove has the longest length possible. Be careful not to hit the edge of the capsu-lorhexis with the phaco probe, and continue to sculpt the grooves deeper into the lens material. The average lens is approximaately 4mm deep centrally and shal-lows peripherally. You should create grooves that are at least half the depth of the nucleus in order to fa-cilitate cracking. [ Figures 1, 2 ] Use the phaco probe and the second instrument to rotate the nucleus 90 degrees and make a second groove orthogonal to the first. Once completed, the two intersecting grooves will form a + sign and will segment the nucleus into four quadrants.

To crack the nucleus into quadrants, a second instru-ment is placed into the groove along with the phaco probe tip. If the instruments are placed too shallow, the crack will be incomplete and the pieces will not separate. The proper method is to place the instru-ments deep within the grooves then pull apart. This will result in a complete crack with separation of the nucleus into distinct pieces. [ Figures 3, 4 ]

Once the nucleus is fully cracked and separated into four quadrants, the phaco settings should be changed. The phaco power settings can be changed to a lower pulse rate, between 10 and 30 pulses per second, a somewhat lower duty cycle of 30-50%, and a lower maximum power setting of approximately half of what was used for grooving. For fluidics, it is important to have more holding power, which means more vacuum. Depending on the phaco needle size, the vacuum level should be between 200 and 400 mmHg, and the flow rate should be between 30 and 50cc/min. Make sure to raise the bottle height to ensure that the inflow of fluid into the anterior chamber exceeds the outflow of fluid in order to main-tain a stable chamber.

Use the phaco probe’s vacuum to bring the pieces out of the capsular bag and to the iris plane. This is the ideal location to phaco-aspirate the nuclear fragments, as it is far from both the corneal endothelium and the capsular bag. Continue to bring the quadrants to the iris plane and phaco-aspirate them. This is the technique of Divide-and-Conquer for nucleus removal.

Starting the GroovesStart the groove as close to the incision as possible for a longer groove length

TYPICAL BETTER

Widen the GroovesAllows more room for placement of thephaco probe and second instrument.

NARROWGROOVE

WIDERGROOVE

Rotate & Create 4 QuadrantsMaintain the Squared Grooves to facilitatecracking of the nucleus into quadrants.

2 HALVES 4 QUADRANTS

Place Instruments Deep in the GrooveDeep placement allows for comletecracking and separation of the nuclear pieces

SHALLOW DEEP

BADincomplete crack

GOODcomplete crack

Starting the GroovesStart the groove as close to the incision as possible for a longer groove length

TYPICAL BETTER

Widen the GroovesAllows more room for placement of thephaco probe and second instrument.

NARROWGROOVE

WIDERGROOVE

Rotate & Create 4 QuadrantsMaintain the Squared Grooves to facilitatecracking of the nucleus into quadrants.

2 HALVES 4 QUADRANTS

Place Instruments Deep in the GrooveDeep placement allows for comletecracking and separation of the nuclear pieces

SHALLOW DEEP

BADincomplete crack

GOODcomplete crack

Figures 1, 2, 3

Figure 4

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lesson 19

Stop-and-Chop Technique of Nucleus RemovalwHILE DIVIDE-AnD-COnqUEr IS An EFFECtIVE tECHnIqUE FOr nUCLEUS rEMOVAL, It DOES tEnD tO rEqUIrE MOrE PHACO EnErgy SInCE tHE CrEAtIOn OF tHE grOOVES AnD DISASSEMbLy OF tHE nUCLEUS IS ACCOMPLISHED wItH ULtrASOUnD EnErgy. MAkIng tHE JUMP FrOM DIVIDE-AnD-COnqUEr tO A FULL CHOP tECHnIqUE IS nOt SIMPLE FOr MAny SUrgEOnS, SO PAUL kOCH, MD, InVEntED StOP-AnD-CHOP.

The technique of Stop-and-Chop uses a groov-ing technique to make a single linear trench in the cataract nucleus. The surgeon then stops,

divides it into two halves, and then chops each half fur-ther. This is an easier transition for most surgeons and results in more efficient surgery. Once the technique of Stop-and-Chop is mastered, many surgeons feel more comfortable transitioning to a full chop technique.

When sculpting the initial groove into the nucleus, it is important to make a sufficiently long trench that ex-tends from the sub-incisional region to the area under the anterior capsular rim. The groove is deeper cen-trally than peripherally, due to the natural shape of the cataractous lens. The width of the groove should be sufficient to allow placement of both the phaco tip as well as the chopping instrument deep within the trench. The initial phaco settings here should be a high pulse mode (80 PPS or more), with a 40-60% duty cycle, and a maximum phaco power of 40-60%. The fluidics should allow for a low vacuum and low flow setting to simply evacuate any emulsified cataract bits from the excavated trench.

Once the instruments are placed deep within the trench, and opposing forces can be gently applied so that the nuclear halves are separated. Care should be taken to separate centrally as well as peripherally in the groove in order to get complete separation of the two halves. If division is incomplete, then the individual nuclear halves will not be easily chopped.

To chop each half, we need to change the phaco and fluidic settings: here a burst mode is my preference as it affords using very little energy. A short burst width of 4-20 milliseconds and a power of 10-40% works well. For those surgeons preferring a pulse mode, try 10-20 PPS (pulses per second), 30-50% duty cycle, and a maximum power of 20-50%.

The fluidics must also be changed to increase the hold-ing power of the nucleus. Try using a higher vacuum level (200-400 mmHg depending on your phaco needle size), and a higher flow rate (30-50 cc/min) with a cor-responding higher bottle height to ensure that the in-

flow is greater than the outflow. To hold the nucleus in place, the phaco probe should be embedded into the nuclear half using ultrasound energy, and then the foot pedal returned to position 2 with just vacuum. Now that the nuclear half is stuck on the phaco tip, bring it up to the iris plane, place the chopper around the edge of the piece, and bring the two instruments together. Once the chopper has cut through the nuclear half and is in close proximity to the phaco tip, pull the instruments apart, towards the left and right to separate the chopped segment. The first chopped segment can be phaco-aspi-rated and the chopping steps repeated to further break both remaining nuclear halves into pieces.

Stop-and-Chop is an important step on the road to performing phaco chop. It’s a technique that can be mastered by all surgeons, regardless of their level of prior experience. For those surgeons who eventually transition to a pure phaco chop technique, it is still helpful to have Stop-and-Chop as a back-up plan for nucleus removal.

Step 1. Make a groove & crackAllows more room for placement of thephaco probe and second instrument

Make a Groove

Crack into Halves

Step 2. Now Chop Each Half

Step 1. Make a groove & crackAllows more room for placement of thephaco probe and second instrument

Make a Groove

Crack into Halves

Step 2. Now Chop Each Half

Figure 1

Figure 2

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lesson 20

Quick Chop Techniques of Nucleus RemovaltHE MOSt EFFICIEnt tECHnIqUE OF nUCLEUS DISASSEMbLy IS A PUrELy MECHAnICAL OnE wHErE tHE nUCLEUS CAn bE CHOPPED IntO SEgMEntS wItHIn A FEw SECOnDS, HEnCE tHE nAME qUICk CHOP. tHESE SEgMEntS CAn tHEn bE EASILy rEMOVED wItH rELAtIVELy LIttLE PHACO EnErgy. COMPArE tHIS tO tHE DIVIDE AnD COnqUEr tECHnIqUE, wHErE A trEMEnDOUS AMOUnt OF ULtrASOnIC EnErgy IS rEqUIrED tO CrEAtE tHE grOOVES tHAt ArE USED tO CrEAtE tHE qUADrAntS. A SIMPLE AnALOgy IStHE SPLIttIng OF FIrEwOOD: A grOOVIng tECHnIqUE IS SIMILAr tO USIng A SAw tO CUt tHrOUgH tHE PIECE OF wOOD, wHErEAS A CHOP tECHnIqUE IS SIMILAr tO USIng An AxE tO CHOP AnD SPLIt tHE FIrEwOOD ALOng tHE grAIn.

The basic concept of chopping is holding the nu-cleus with the phaco probe while the chopping instrument splits it into pieces. The most com-

mon difficulty that beginning surgeons encounter when attempting chopping techniques is failure to adequately fixate the nucleus so that it can be chopped. If you’re going to use a fork and knife to cut a piece of meat, you must first hold and immobilize the meat with the fork so that the knife can do the cutting. Similarly, the phaco probe must achieve a high enough vacuum level to firmly fixate the nucleus so that the chopper can do the mechanical splitting of the cataract.

A high vacuum level is required to achieve the hold-ing power that we desire for chopping. Depending on the phaco needle size that you are using, the vacuum level should be between 250 and 400mmHg, and if

you are using a peristaltic fluid pump, remember that total occlusion of the phaco tip is required to achieve the maximum preset vacuum level. With the vacuum setting high, bury the phaco tip into the nucleus using phaco power (foot pedal position 3), then once you have full occlusion of the tip, back off the pedal into position 2 so that the nucleus is being held by the high vacuum level. Now the cataract is well-fixated and we are ready to employ a chop technique.

HORIzONTAL CHOPPINgThe original technique of chopping described by Naga-hara is a horizontal chop. The phaco probe is embedded into the nucleus and the chopper is passed under the capsulorhexis and towards the lens equator. Once at the lens equator, the chopper is brought towards the pha-co tip. It is this action of moving the chopper and the

phaco tip together that does the chopping. When this is accomplished, the pieces need to be separated by pull-ing the two instruments apart. For most surgeons, this means bringing the chopper towards the left, while the phaco probe is pushed towards the right. A complete separation of the two pieces is required for complete mobilization of the halves and for further chopping into segments. [ Figure 1 ]

VERTICAL CHOPPINgIn a dense nucleus, vertical chopping is a very effec-tive and safe technique. The phaco tip is embedded into the nucleus and a high vacuum level is used to fixate it securely. The chopper is then placed vertically into the center of the nucleus, well within the confines of the capsulorhexis. Once the chopper and phaco tip are both fully buried in the center of the nucleus, the two instruments are pulled apart: the chopper to the left and the phaco probe to the right, thereby separating the two nuclear halves. These nuclear halves can then be further chopped into smaller segments and emulsified. [ Figure 2 ]

TILT AND CHOPTo minimize the stress on the capsular bag, which is par-ticularly helpful in cases of pseudoexfoliation or trauma where there is zonular weakness, the nucleus can be tilted out of the capsular bag. A relatively large capsu-lorhexis of 5 mm or more, combined with hydrodissec-tion or viscodissection, will aid in partially prolapsing the nucleus out of the capsular bag. With the nucleus tilted out of the capsular bag, it is very easy to place the chopper around the lens equator or even behind the nucleus. The chopper is brought towards the phaco tip and the two instruments are pulled apart to create the two nuclear halves. The tilt and chop technique is my preferred technique for very dense cataracts, where a significant amount of force is required to propagate the chop through the nucleus. By placing the chopper be-hind the nucleus, with the phaco probe in front of it, I am able to exert a powerful chopping force while still being very gentle to the zonules and other intra-ocular structures. [ Figure 3 ]

Chopping techniques are quickly becoming the pre-ferred method for cataract surgery due to their inherent efficiency and greater safety. While the technical skill required for chopping is high, the great majority of oph-thalmologists can master with practice.

Horizontal Chop

Vertical Chop

Tilt & Chop

Figures 1, 2, 3

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lesson 21

Cortex RemovalOnCE tHE nUCLEUS IS rEMOVED, tHE rEMAInIng LEnS COrtICAL MAtErIAL MUSt bE tHOrOUgHLy CLEAnED FrOM tHE CAPSULAr bAg. It IS nOt ACCEPtAbLE tO LEAVE A SIgnIFICAnt AMOUnt OF LEnS COrtEx In tHE EyE At tHE EnD OF tHE CAtArACt SUrgEry SInCE It wILL InDUCE InFLAMMAtIOn AnD MAy AFFECt tHE PAtIEnt’S qUALIty OF VISIOn AnD LEVEL OF COMFOrt. COrtEx rEMOVAL rEqUIrES A DELICAtE tOUCH SInCE wE ArE wOrkIng In DIrECt PrOxIMIty tO tHE FrAgILE CAPSULAr bAg.

The amount of cortex adherent to the capsular bag is proportional to the effectiveness of the hydrodissection performed prior to nucleus re-

moval. As much of the nucleus and epi-nucleus as pos-sible should be removed with the phaco probe prior to switching to the irrigation/aspiration (I/A) hand-piece. The I/A hand-piece has a much smaller opening as compared to the phaco needle, which allows for more control and a higher vacuum level while maintaining the stability of the anterior chamber.

Any small, stray nuclear fragments can be removed by using the I/A tip in combination with a second instru-ment, either a chopper or a spatula, via the paracentesis. When the small nuclear chips become stuck at the I/A tip opening, simply use the second instrument to push them into the port. The action is similar to using a fork to mash potatoes, and is a mechanical means to force the nuclear chips into the small I/A suction port.

For cortex removal, the I/A probe is placed under the edge of the capsulorhexis and the cortex is grabbed from within the capsule, near the lens equator [ Figure 1 ]. The key for efficient cortex removal is to move in a cir-cumferential manner. You should aim to grab at least a few clock hours of cortex by moving circumferentially prior to bringing the probe radially towards the center of the anterior chamber. The goal is to remove a few large sheets of cortex material instead of pulling many small strips of cortex. Removing a large sheet of cor-tex allows for safer and more efficient cortical clean-up

and is less likely to result in residual cortical material in the capsular bag.

My preferred technique is to remove about three clock hours of cortex at a time with the circumferential tech-nique [ Figure 2 ]. When it comes to the sub-incisional cortex, the I/A tip can be positioned so that it is fac-ing inferiorly, towards the underlying capsular bag. Once the cortical piece is held via the suction of the I/A tip, move the probe towards the center of the anterior chamber and bring the port upwards to complete the aspiration.

If the posterior capsule is inadvertently suctioned during the removal of the lens cortex, care should be taken to stop and release it. The foot pedal has a posi-tion called ‘reflux’ where the vacuum is stopped and the fluid pump is reversed to release any trapped ma-terial. This reflux position is typically used to reverse the aspiration of fluid and to release the tissue, such as posterior capsule or iris that was inadvertently grabbed. If spider-like wrinkles [ Figure 3 ] appear on the posterior capsule, the cause is most likely aspiration of the cap-sule and you should immediately release the vacuum by going to foot-position 1. If that does not release the capsule, go to reflux position.

When small, residual cortex fragments are left on the posterior capsule, a gentler irrigation and aspiration set-ting can be programmed into the phaco machine. Using a setting such as ‘capsule polish’ or ‘capsule vacuum’, we can use low flow and low vacuum to remove these last few bits of cortex while being very careful not to damage the posterior capsule.

In small pupil cases, remember that the cortex needs to be removed from the equatorial region of the capsular bag, which may be out of view, blocked by the iris tissue. Care should be taken to remove as much cortex as pos-sible so that post-op inflammation and posterior capsule opacification are minimized. Use of the new silicone-coated soft irrigation/aspiration tips allows a higher mar-gin of safety since no metal will come in contact with the posterior capsule.

Our goal at the end of cortex removal is to have a clean and clear capsular bag, ready to accept our intra-ocular lens implant.

Grab cortex from within the capsule

Aspirate 3 clock hours of cortexin a circumferential manner

Spider-like radial lines indicate dangerous aspiration of the capsule

Grab cortex from within the capsule

Aspirate 3 clock hours of cortexin a circumferential manner

Spider-like radial lines indicate dangerous aspiration of the capsule

Figure 1

Figures 2, 3

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lesson 22

IOL InsertionOnCE tHE CAPSULAr bAg IS CLEAn AnD CLEAr, It SHOULD bE FILLED wItH VISCOELAStIC. InJECt VISCOELAStIC AS yOU InSErt tHE CAnULA IntO tHE EyE SO tHAt tHErE IS nEVEr Any DIrECt COntACt OF tHE CAnULA wItH tHE POStErIOr CAPSULE. OnCE tHE AntErIOr CHAMbEr IS InFLAtED, PASS tHE CAnULA UnDEr tHE CAPSULOrHExIS EDgE AnD COMPLEtELy FILL tHE CAPSULAr bAg. [ Figure 1 ] yOU wAnt tHE EyE tO bE FIrM AnD rEADy tO ACCEPt ItS nEw LEnS IMPLAnt.

The recent advances in IOL technology have been a tremendous benefit to surgeons and pa-tients alike—with better optics and improved

bio-compatibility, and with the introduction of new lens materials that permit insertion through smaller and smaller incisions. The three main IOL classifications for insertion are: rigid IOLs, foldable IOLs, and inject-able IOLs. Each is inserted differently.

Rigid IOLs are typically made of polymethyl methac-rylate (PMMA) which is a well-tolerated non-flexible plastic. These IOLs tend to be single piece, made en-tirely of PMMA, and, due to their rigid nature, they require a larger incision for insertion, typically 0.5mm greater than the optic size. Most 6.0mm optic PMMA IOLs can be passed through a 6.5mm incision. An inci-sion as large as this should not routinely be made in the cornea; rather, a scleral tunnel incision should be created. This larger incision will cause a long-term as-tigmatic effect, which can often be lessened by proper closure with sutures. Due to the large incision size, the PMMA IOLs tend to be used rarely in most modern practices.

Foldable IOLs are often made of acrylic or silicone, and are designed to be folded in half, held with forceps, and then placed within the eye. This allows an IOL with an optic size of 6.0mm to be inserted through an inci-

mild to moderate astigmatic effect, and it can be closed without sutures.

Injectable IOLs are also made of acrylic or silicone, and are designed to work with a specific IOL injector system. This allows the IOL to be completely shielded from contacting the ocular surface during insertion, and it allows for smaller incisions of less than 3.0mm, and sometimes even less than 2.0mm. Once the IOL is in-jected into the eye, it opens up and resumes its full size and shape, and the injector can be removed from the incision. These smaller incisions have the least astig-matic effect and tend to seal the best, and the future trends will be to move towards smaller and smaller in-cisions and less invasive surgery.

The technique for inserting all of these IOLs is similar: the leading haptic is placed into the capsular bag, fol-lowed by the optic, then finally the trailing haptic is also placed into the bag. Note that IOLs have a proper front and back surface, and they should not be placed into the eye upside down. The normal configuration is with

the haptics in the same orientation as the letter “Z”, and not in the “S” formation. [ Figure 2 shows the proper “Z” ori-

entation of the haptics. ] Once the IOL is completely within the capsular bag, it can be gently rotated with a second instrument to ensure that it is well-positioned. In some situations, such as with a compromised posterior cap-sule, the IOL may be intentionally placed with the cili-ary sulcus – the space between the posterior surface of the iris and the anterior lens capsule. With a typical 5.0mm capsulorhexis, a 6.0mm optic will be held in place by the edge of the anterior capsule for 360 degrees, and the long-term stability of the IOL is ensured. With the lens completely within the capsu-lar bag, the viscoelastic needs to be removed from the eye. [ Figure 3 ] Using high flow and high vacuum, the viscoelastic should be aspirated, with care taken to tilt the IOL to the sides to remove any viscoelastic that is sequestered behind the IOL optic. At this point the an-terior chamber can be filled with balanced salt solution, and the incisions can be sealed.

Inject Viscoelastic in Capsular Bag

Insert IOL into Capsular Bag

Remove All Viscoelastic

Inject Viscoelastic in Capsular Bag

Insert IOL into Capsular Bag

Remove All Viscoelastic

Figure 1

Figure 2 Figure 3

sion of about 3.0-3.5mm, which can be made safely in the cornea. Once the IOL is inserted within the eye, the forceps are opened, the IOL is released, and the forceps can be removed. An incision of 3.0mm or so has only a

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lesson 23

Incision Closure & DressingsFOr bEgInnIng PHACO SUrgEOnS, I rECOMMEnD SUtUrIng tHE InCISIOnS At tHE EnD OF tHE SUrgEry. tHIS gIVES bEttEr SEALIng OF tHE InCISIOnS, AnD It gIVES tHE SUrgEOn An OPPOrtUnIty tO EnHAnCE tHE FInE MOtOr SkILLS tHAt ArE InVOLVED In MICrOSCOPIC SUtUrIng. tHESE tIny SUtUrES, tyPICALLy 10-0 In SIzE, CAn bE CHALLEngIng tO USE gIVEn tHEIr LOw tEnSILE StrEngtH AnD tHE SMALL CIrCULAr nEEDLES.

The sutures typically come with semi-circular needles, which create circular paths when they are passed through tissue. There should be no

linear pushing with these needles, otherwise they will bend and distort the tissues. Rather, the movement used to pass these sutures is similar to turning a screwdriver in a circular motion. [ Figure 1 ] Sutures should be placed symmetrically so that an even amount of tissue on ei-ther side of the incision is captured by the suture. This results in optimum holding power of the incision, better long term stability, and a lower likelihood of cheese-wiring through the tissues. [ Figure 2 ]

The entry angle of the suture plays a large role in de-termining the depth of the suture. Since needle creates a circular path, acute angles of less than 90 degrees re-sult in shallow passes, and obtuse angles of more than 90 degrees result in deeper passes. If the needle entry angle is 90 degrees, then the circular path of the needle will result in a depth equal to the radius of curvature of the needle. [ Figure 3 ]

The suture holding power is greatest directly under the suture itself, and this diminishes as you move further away. The resulting forces from the suture result in a diamond-like distribution pattern. [ Figure 4 ]

Shorter sutures distribute their force over a smaller area, and therefore more sutures are required to close the incision or wound. This may be helpful in situations where higher strength closure of the wound is required. Sutures that are placed at a more ideal length will pro-vide good holding power at the incision while minimiz-ing the number of sutures required for a given length of incision. Overly long sutures tend to distribute the closure force over too broad an area, and, as a result, they may give less effective holding power for the inci-sion. [ Figure 5 ].

Suture placement in clear corneal incisions should be radial, much like the spokes of a bicycle wheel. The needle should be grasped at about one-third the distance from the swaged end to the point, and the needle-holder

should be unlocked before passing the suture. When ty-ing nylon monofilament sutures, it is customary to tie interrupted sutures with three knots in a 3-1-1 manner: the first knot should be three throws, and the second and third knots should be one throw. These three knots are placed in alternating directions in order to create square knots. Sutures placed in the cornea can then typically be rotated so that the knots are buried within the corneal stroma, which aids in patient comfort while helping to prevent unraveling of the knots.

Placing a suture with good depth, symmetry, spacing,

length, and tensile force is an art and an integral part of ophthalmic surgical technique. The incisions can now be checked for leakage by using a small sponge and pressing on the lip of the wound. Any leakage will cause the sponge to swell and absorb the fluid. This is an indication of insufficient wound closure, and addi-tional sutures may be needed. Note that if two or more sutures are placed in the same incision, they must be at the same tension. If there are normal tension sutures on either side of a tight suture, then these normal tension sutures will appear to be loose. Only when the tight suture is removed will the tension on the other sutures appear normal again. The balance in throwing a suture to close a corneal incision is: too tight and there is a lot of induced astigmatism; too loose and the incision will leak. Finding the right balance only comes with prac-tice and experience.

Figure 1. Circular Path of the Needle

To pass a suture with a semi-circular needle, the movement is like turning a screwdriver in circular motion. Excessive pushing in a linear manner will cause the needle to bend and the tissues to distort.

Figure 2. Symmetrical Suture Placement

Symmetrical suture placement (B) results in optimal power and wound closure. (A) and (C) do not provide the same security.

A. B. C.

Figure 3. Entry Angle Determines Depth

The entry angle of the needle will determine the depth of the suture placement. (A) Acute angles result in shallower sutures. (B) Right angles result in nomal depth, equal to the radius of the needle. (C) Obtuse angle result may result in excessively deep suture passes.

A. B. C.Acute Angle < 90˚

Shallow DepthRight Angle = 90˚

Nomal DepthObtuse Angle > 90˚

Excessive DepthFigure 4.Suture Holding Power

The holding power is strongest under the suture andit decreases as you move futher away, distributing the forces in a diamond shape.

Suture

Incision / Wound

Figure 5.Suture Length and Spacing

(A) Short sutures distribute their force over a smaller area, and therefore more sutures are requird to close the incision. (B) The ideal balance of suture length and spacing, where the forces provide good holding power for the entire incision. (C) An overly long suture may distribute the forces over too large an area and therefore give less effective holding power for the incision.

short ideal long

A. B. C.

Figure 1. Circular Path of the Needle

To pass a suture with a semi-circular needle, the movement is like turning a screwdriver in circular motion. Excessive pushing in a linear manner will cause the needle to bend and the tissues to distort.

Figure 2. Symmetrical Suture Placement

Symmetrical suture placement (B) results in optimal power and wound closure. (A) and (C) do not provide the same security.

A. B. C.

Figure 3. Entry Angle Determines Depth

The entry angle of the needle will determine the depth of the suture placement. (A) Acute angles result in shallower sutures. (B) Right angles result in nomal depth, equal to the radius of the needle. (C) Obtuse angle result may result in excessively deep suture passes.

A. B. C.Acute Angle < 90˚

Shallow DepthRight Angle = 90˚

Nomal DepthObtuse Angle > 90˚

Excessive DepthFigure 4.Suture Holding Power

The holding power is strongest under the suture andit decreases as you move futher away, distributing the forces in a diamond shape.

Suture

Incision / Wound

Figure 5.Suture Length and Spacing

(A) Short sutures distribute their force over a smaller area, and therefore more sutures are requird to close the incision. (B) The ideal balance of suture length and spacing, where the forces provide good holding power for the entire incision. (C) An overly long suture may distribute the forces over too large an area and therefore give less effective holding power for the incision.

short ideal long

A. B. C.

Figures 1, 2, 3

Figures 4, 5

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lesson 24

To prevent the dreaded complication of endo-phthalmitis, topical antibiotics are often pre-scribed during the immediate post-op period.

The most commonly used topical antibiotics have broad-spectrum coverage, such as the case with fluoro-quinolones, and they are administered before surgery and then for the first week or so after surgery.

To ensure optimum patient recovery of good, clear vision, the inflammation must be controlled with po-tent topical medications such as corticosteroids and NSAIDs (non-steroidal anti-inflammatory drugs). The most commonly prescribed corticosteroids are pred-nisolone acetate and dexamethasone, which are dosed for at least 2 weeks after surgery, and sometimes for as long as 8 week after more complex cases. While the steroids are efficacious at reducing the inflamma-tion, they can induce a glaucomatous state as a side effect. The intra-ocular pressures should be monitored in post-op patients to ensure that this does not hap-pen. NSAIDs are also a useful adjunct to steroids since they can help reduce inflammation further, offer pain relief, and help to prevent the development of cystoid macular edema.

Post-op Medications & Follow-upAFtEr rOUtInE PHACOEMULSIFICAtIOn SUrgEry, tHE twO PrIMAry COnCErnS ArE rESOLUtIOn OF tHE SUrgICALLy InDUCED InFLAMMAtIOn AnD PrEVEntIOn OF InFECtIOn. tHE PAtIEnt’S COMFOrt AnD rEtUrn OF SHArP VISIOn ArE ALSO DEPEnDEnt On A SUCCESSFUL POSt-OP COUrSE AnD rECOVEry.

The routine post-op care of phacoemulsification pa-tients involves seeing them the day after surgery to monitor the initial healing response. On post-op day 1, the incisions should be sealed and water-tight, the anterior chamber should be deep and formed, and the IOL should be in good position. The intra-ocular pres-sure should be normal to mildly elevated. A high intra-ocular pressure typically indicates that some residual viscoelastic was left in the eye at the end of the case and should be treated with topical or oral IOP-lower-ing medications. The vision on post-op day 1 is depen-dent on the clarity of the cornea—the less ultrasound energy that was placed in the eye, the clearer the cor-nea and the better the vision. Most cases of corneal edema will resolve within a few weeks.

The patients are typically seen again at post-op week 1 or 2, at which point the vision should be better, the inflammation should be less, and the patient should be happy with the surgical result. IOP is monitored to make sure that it is within normal range, and the antibiotic medication can be stopped. The next visit will be at ap-proximately 4-6 weeks after surgery, where the retina can be checked for any macular or peripheral lesions.

WE ARE TRULy FORTUNATE TO BE OPHTHALMOLOgISTS—it’s rewarding and challenging to perform complex microsurgery to restore the gift of sight to our patients, and it’s a pleasure to put the technical art and science of surgery into practice. I’m sure that many others share my passion and pride, and I hope that we can spread it to future generations – to the people who will one day perform cataract surgery on our eyes.

this 24 part series can serve as a good foun-dation for the principles of phacoemulsification surgery for ophthalmologists. It takes years of practice and scores of cases to become profi-cient at phaco, and a lifetime to truly master it. I encourage you to pursue further training, studies, and mentoring in cataract surgery and to truly enjoy the process. I would like to thank the people who have worked so hard to put this project together, including Mridula Chettri Singh and her team, bausch & Lomb for their support, and the other important people behind the scenes that have made this idea a success.

- Uday Devgan, MD, FACS los angeles, california, usa

course summary

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Published By ILX MEDIA gROUP Chairman James f. marshall • Chief Executive Officer Grant J. prigge • Chief Operating Officer Jeffrey K. parker

Ophthalmology world report is a monthly English-language publication published for the owners of ILx Media group at new Delhi, India. Available on a controlled / free for distribution basis to qualified practicing ophthalmologists in India. Ch Mahender Singh Farms, Club Drive road, ghitorni, new Delhi 110030Copyright 2008 ILx Media group. All rights reserved. no part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photography, recording or information storage and retrieval system, without permission in writing from the publisher. Authorization to photocopy items for internal or personal use of specific clients, can be granted by ILx Media group for libraries and other users registered with the publishers.

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global editorial board Chief Medical Editor, India Edition Dr. P. namperumalsamy, MD Chief Medical Editor, China Edition Dr. zhang kang, MD, PhD Executive Editors Dr. rajvardhan Azad, MD • Dr. robert gale Martin, MD • Dr. He wei, MD Senior Advisory Board Dr. ge Jian, MD • Dr. Lingam gopal, MD • Dr. kulin kothari, MD • Dr. Li xiaoxin, MD • Dr. gullapalli n. rao, MD • Dr. xie Lixin, MD Consulting Editor Shashi kapoor, MD global Column Editors Cataract Dr. Debasish bhattacharya, MS • Dr. Mahipal Sachdev, MD • Dr. ye zilong, MD Retina Dr. Manish nagpal, MS • Dr. biju raju, MS • Dr. tang Shibo, MD Refractive Dr. Lu wenxiu, MD • Dr. D. ramamurthy, MD Cornea Dr. rajesh Fogla, Dnb, FrCS • Dr. Liu zuguo, MD Dr. Sheng Minjie, MD glaucoma Dr. tanuj Dada,MD • Dr. He Mingguang, MD Occuloplasty/ Ophthalmic Education Dr. A.k. grover, MD Uvea Dr. Vishali gupta, MD • Dr. yang Peizeng, MD Orbit/Oncology Dr. Santosh Honavar, MD Medical Ophthalmology Dr. Mallika goyal, MS Neuro Ophthalmology Dr. Satya karna, DO, Dnb Contributing Editors Dr. Au Eong kah-guan, MD • Dr. David F. Chang, MD • Dr. Debraj Shome, DO, Dnb • Dr. gaurav Shah, MD • Dr. geoffrey tabin, MD • Dr. Sanghamitra burman, MD • Dr. Parijat Chandra, MD • Dr. J.E. McDonald, MD • Dr. John S.M. Chang, MD • Dr. Luther Fry, MD • Dr. r. ramakrishnan, MD • Dr. y. ralph Chu, MD • Dr. rohit Saxena, MD • Dr. rishi Swarup, MD • Dr. Savari Desai, MD • Dr. Suhas Haldipurkar, MD • Dr. Seenu Hariprasad, MD • Dr. Uday Devgan, MD • Dr. Usha raman, PhD • Dr. zhang zhenping, MD Editorial Editorial Director Jeffrey k. Parker Managing Editor, India Edition Mridula Chettri Singh International Editor Larry Schuster News and Supplements Editor Stephanie Schweimnitz Assistant Managing Editor, China Edition Anny xiao Editors Dr. Hao xiaojun • Chelsea zhao Publishing &Advertising group Publisher grant J. Prigge [email protected] +86 21 6359 3631 x 888 Business Development Director Jaideep bajaj [email protected] +91 98101 83544 group News Editor Lea zang CME Specialist Steven tresker News Reporter Myra Colis Copy Editor yang Li Art Direction, India Seoyoung kang. [email protected] Circulation Associate Eunice zhang

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