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
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
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).
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
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
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
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
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.
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
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
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.