The Case for Single-Incision, Single-Instrument Phacoemulsification Through a

Clear Corneal Microincision

Robert M. Kershner, M.D., F.A.C.S.

Eye Laser Center

Suite 303, 1925 West Orange Grove Road

Tucson, Arizona 85704-1152 U.S.A.

Phone (520) 797-2020 FAX (520) 797-2235

www.asiteforeyes.com

INTRODUCTION

As a child, your mother admonished you to hold your glass of milk with two

hands to prevent spilling the milk onto the kitchen floor. As an adult, you

learned you could hold your glass with one hand, still be in control of its

contents and have one hand free to help yourself to an hors d'hoeuvre. So

it is with one-handed phaco, a procedure that I call single-incision,

single-instrument phaco because you still use two hands. Only you use them

with one incision, not two. As an increasing number of surgeons have adopted

phacoemulsification as the preferred method for cataract removal, since it's

introduction as a method of cataract surgery over one-quarter of a century

ago, surgeons have learned what works best for them, to accomplish this

delicate and demanding microsurgical procedure. For most who learned phaco,

using a second instrument to stabilize the cataract became part of the

learning process. Unfortunately, with it, came the requirement to have two

incisions. And in the case of today's microincision refractive cataract

procedure, two incisions are not better than one! I have been convinced for

over twenty years, that the delicate maneuvers of cataract surgery can be

accomplished more effectively, and more efficiently, through a single

incision, with one instrument at a time. All of today's modern cataract

extraction techniques, whether it be, divide and conquer, chip and flip, or

cracking and flipping, can be accomplished easier and with less manipulation

with one instrument-through one incision. The advantages of removing a

cataract through a single small incision has been recognized by surgeons the

world over. With it, phacoemulsification has made it possible to abandon

suture closure, utilize smaller and smaller incisions, replace injection

anesthesia with topical anesthesia, and improve our ability to correct

refractive error with cataract surgery (1).

Today's new techniques of topical anesthesia, clear corneal cataract surgery,

and injection of elastic intraocular lenses through small microincisions have

placed new constraints on the ability of the surgeon to perform

phacoemulsification. Introducing the phacoemulsification tip through a small

clear corneal refractive microincision limits access to the cataract and can

restrict the surgeon's ability to manipulate the lens within the capsular

bag. As a result of the challenge and demands of smaller incision cataract

surgery, surgeons have adopted several new approaches to the strategy for

phacoemulsification.

All methods of cataract removal have essentially one goal in common: to take

a large anatomic structure (the lens) and dismantle it into smaller pieces

for ease of removal through an incision smaller than the overall size of the

lens. Whether one adopts a divide and conquer technique, a quadrantic

phacoemulsification method, a chip and flip, or a stop and chop method, the

goal remains the same. One can either mechanically divide the cataract into

segments and remove the individual segments, or chip away at the larger

structure and remove it piece by piece.

Many surgeons use two incisions through the cornea, and two instruments for

phaco, one for the phaco tip and one for a sideport lens manipulating

instrument. I do not believe that a second-handed instrument is necessary

for effective and efficient phacoemulsification of the cataract. There are

distinct advantages of maintaining the phaco incision as one incision.

Placing an additional incision in the eye is not only unnecessary but it

increases the likelihood of incisional leaks, an additional portal for

infection, synechiae and encourages excessive instrumentation of the eye.

SINGLE INCISION PHACOEMULSIFICATION -THE THREE-STEP KEYHOLE TECHNIQUE

Early in its development, phacoemulsification was performed entirely through

a single incision. This single incision/single instrument phacoemulsification

technique has previously been called a "one-handed" phaco technique. The

name is a misnomer however, as two hands are required to successfully perform

phaco. They just don't each require their own incision! The maneuvers of

lens rotation and segmental removal of the cataract can be performed with a

single hand on the instrument thus freeing the left hand for manipulating the

eye, stabilization of the globe, retrieval of instruments, or to stabilize

the phacoemulsification handle and tubing.

It is important that the surgeon adopt an efficient method of

phacoemulsification through today's small corneal microincisions prior to

adopting a single-incision technique. The single instrument phaco technique

is elegant, more efficient, easier to learn, and less traumatic to the eye,

but it does require a strategy and a masterful technique. Single-Instrument,

Single Incision phaco (Si Si Phaco) ain't for sissies! The time is right, as

we enter the next millennium, to take a new look at an old technique - the

single incision/single instrument phacoemulsification method that I call the

keyhole technique (6).

INCISION CONSTRUCTION:

The clear corneal microincision has placed new demands on the surgeon for

evacuating the cataract through a single small corneal incision. These

incisions can be very unforgiving--they must not be distorted, torn or heated

during the procedure without creating profound refractive effects for the

eye.

Incision construction is critical to a successful phacoemulsification

procedure. The incision needs to be accurately sized for the size of the

phacoemulsification tip to be used. Today's microincision corneal procedures

utilize an incision of 2.5 mm or smaller that must accommodate a micro phaco

tip. The clear corneal refractive microincision technique has been described

elsewhere (1,2,3). Following fabrication of the clear corneal incision with

a blade specificallly desinged for the clear conreal incision such as a

diamond keratome or the new disposable clear corneal incision system marketed

by Becton Dickinson Ophthalmic Systems, the anterior chamber is entered, and

a viscoelastic placed to deepen the chamber. Capsulorrhexis is performed

using the technique of one-step capsulorrhexis with a cystotome/forceps

which I developed in 1984 (4,5).

In early phacoemulsification methods, it was important to maintain the

position of the cataractous lens within the capsular bag to stabilize it.

Following the introduction of capsulorrhexis, it was found that the limited

access into the capsular bag created difficulties for the surgeon in rotating

the lens for emulsification and removal. To facilitate these maneuvers,

hydrodissection was adopted to cleave the strong cortical attachments between

the lens capsule and the cortex of the cataract. By slipping a curved 27

gauge cannula through the incision and positioning it beneath the

subincisional anterior lens capsule, a fluid wave can be created across the

posterior lens. This maneuver prematurely loosens the cortex beneath the

incision making it easier to remove with irrigation and aspiration later in

the procedure.

PHACOEMULSIFICATION PARAMETERS

It is preferable to use a phacoemulsification machine whose individual

parameters are controllable by the surgeon. Phacoemulsification power should

be set to a reasonable level which allows the surgeon adequate control with

the phaco pedal. I will rarely use phaco powers above 20-30%. With single

incision phacoemulsification, a higher head of pressure is required to

maintain the chamber, allowing the delicate maneuvers with the phaco tip

without danger of collapsing the capsular bag or injuring the corneal

endothelium.

STEP 1 - CENTRAL SCULPTING

When performing central sculpting, occlusion of the phacoemulsification tip

rarely occurs. The goal of central sculpting is to remove the densest,

hardest part of the nucleus at the beginning of the procedure when it is

easiest to do so. The lens is kept entirely within the capsular bag. Using

the phacoemulsification tip, gentle sculpting of the central nucleus is

completed.

STEP 2: CREATING AN INFERIOR NOTCH - THE KEYHOLE METHOD

Once central sculpting is completed, the surgeon is left with a cortical

bowl. To remove the cortical bowl, a notch is aspirated to release the

tension on the cortical ring of the cataract.

STEP 3: REMOVAL OF THE CORTICAL RIM

Using the phacoemulsification tip as a fulcrum, the remaining cortical rim

can be gently rotated counterclockwise and removed.

STEP 4: REMOVAL OF THE NUCLEAR PLATE

Following complete removal of the cortical rim, a small flat section of

posterior nucleus remains. Using a modification of the maneuver developed by

David Brown, M.D. of Florida, the phacoemulsification tip is used to push the

nucleus against the equator of the capsule and flip it over. The remaining

nuclear plate is elevated off the posterior capsule and removed. s for the

piece to come to the tip.

INSERTION OF THE LENS

The capsular bag is inflated with viscoelastic, and the single piece

injectable lens is inserted into the capular bag in one maneuver. If a toric

IOL is used, it is aligned with the steep meridian.

CONCLUSION

The single instrument phacoemulsification procedure is quick, requires only

one incision, one instrument, and is less traumatic to the eye. The benefits

of this technique are less induced astigmatism, more rapid visual recovery,

better uncorrected visual acuity, and a happier patient with one hole in

their eye instead of two (1). Any difficulties a surgeon may encounter when

using a single instrument technique, are quickly overcome after the surgeon

makes the mental conversion from holding his glass with one hand instead of

two. Suddenly there appears another free hand to help, that used to be tied

up in the second port

The single incision/single instrument approach to phacoemulsification paves

the way to a fully integrated micro incision refractive cataract procedure.

With less portals into the eye, the procedure is amenable to topical

anesthesia. Suturing is no longer required. Bandaging is unnecessary. The

single microincision allows injection of one-piece elastic intraocular lenses

without enlarging the incision. Visual recovery is almost immediate and

usually without eyeglasses.

The ultimate goal of outpatient cataract surgery is less intervention with

better visual results and more rapid visual rehabilitation. Isn't it about

time surgeons adopt an approach where less is more?

About the Author

Robert M. Kershner, M.D., F.A.C.S. is Director of Ophthalmic Surgery at the

Orange Grove Center for Corrective Eye Surgery in Tucson, Arizona U.S.A. and

Clinical Professor of Ophthalmology at the University of Utah Medical Center

in Salt Lake City, Utah, U.S.A. Dr. Kershner has published over two hundred

scientific articles and twelve textbooks on eye microsurgery. He has

developed numerous surgical instruments and techniques and lectures

ophthalmic surgeons throughout the world on microincision refractive cataract

surgery.

REFERENCES

1. Kershner, RM. "Clear corneal cataract surgery and the correction of

myopia, hyperopia and astigmatism." Ophthalmology 1997,104(3);381-9.

2. Kershner, RM. ed. Refractive Keratotomy for Cataract Surgery and the

Correction of Astigmatism. Thorofare, NJ: Slack, 1994.

3. Kershner, RM. "Keratolencticuloplasty: Arcuate keratotomy for cataract

surgery and astigmatism." J Cataract Refract Surg 1995;21:274-7.

4. Kershner, RM. "One-step forceps for capsulorhexis." J Cataract Refract

Surg 1990;16:762-5.

5. Kershner, RM. "Embryology, anatomy and needle capsulotomy." In: Koch PS,

Davison JA, eds. Textbook of Advanced Phacoemulsification Techniques.

Thorofare, NJ: Slack, 1991;35-48.

6. Kershner, RM. "Sutureless one-handed intercapsular phacoemulsification:

The keyhole technique." J Cataract Refract Surg 1991;17(suppl):719-25.