Intercapsular Phaco Flip-Robert M. Kershner, MD, FACS
Director of Cataract and Refractive Surgery, Eye Laser Center, Tucson, Arizona USA
Clinical Professor of Ophthalmology, University of Utah School of Medicine, Salt Lake City, Utah
Ik Ho Visiting Professor of Ophthalmology, Chinese University of Hong Kong
Address Correspondence to: Eye Laser Center
1925 West Orange Grove Road
Tucson, Arizona USA 85704-1152
Phone: (520) 797-2020 Fax: (520) 797-2235
Today's techniques have placed new constraints on the ability of the surgeon to perform phacoemulsification through the microincision. 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 need to adopt several new approaches in 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 incision/single instrument phacoemulsification is a method that I call the keyhole technique.
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. Following fabrication of the clear corneal incision with a blade specifically designed for the clear corneal incision such as a diamond keratome or the new disposable clear corneal incision system developeded by Becton Dickinson Ophthalmic Surgical, the anterior chamber is entered, and a viscoelastic placed to deepen the chamber.
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 (Figure 12). 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.
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 (Figure 13), 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. I keep the irrigation bottle at a height of 115 cm.
STEP 1 - CENTRAL SCULPTING
When performing central sculpting (Figure 14), 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. If the lens nucleus is dense, a deep and wide sculpting is performed. If the lens is soft, a narrow and shallow sculpting is performed.
STEP 2: SEGMENTAL REMOVAL OF THE CORTICAL RIM-THE KEYHOLE METHOD
Once central sculpting is completed, the surgeon is left with a cortical bowl. To remove the cortical bowl (Figure 15), a notch is aspirated to release the tension on the cortical ring of the cataract in the peripheral cortex. Using the phacoemulsification tip as a fulcrum, the remaining cortical rim can be gently rotated clockwise. Two clock hours of cortical rim are then gently aspirated into the central triangle of safety, and with minimal phacoemulsification are removed.
STEP 3: REMOVAL OF THE NUCLEAR PLATE
Following complete removal of the cortical rim, a small flat section of posterior nucleus remains. To remove this without risking injuring the posterior capsule (Figure 16), I use a mini phaco flip technique. The phacoemulsification tip is used to push the tip of the nucleus plate against the equator of the capsule and flip it over. Allow the piece to come to the tip rather than chase it around the posterior chamber. Using short bursts of phaco power, the final piece can be safely elevated off the posterior capsule and removed.
INSERTION OF THE IOL
Fill the capsular bag with viscoelastic, being careful not to overfill the chamber, but rather inflate just enough to open the capulorrhexis (Figure 17). The single piece injectable lens is carefully loaded into the injector and inserted into the capular bag in one maneuver. If a toric IOL is used (Figure 18), it is aligned with the steep meridian, by placing the anterior lens marks at the proper location. The lens is then injected in one simple maneuver into the capsular bag at the proper meridian (Figure 19). The result is a carefully controlled procedure that results in the cornea being reshaped into a spherical and optically sound structure (kerato-) with the proper intraocular lens fully correcting the spherical error (-lenticuloplasty) (Figure 20).
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 the micro incision is maintained, less unwanted astigmatism is induced, the surgeon has better control at correcting pre-existing refractive error with a more predictable refractive outcome. This is translated into a rapid visual recovery for the patient. Any difficulties a surgeon may encounter when using a single instrument technique, are quickly outweighed by the benefits of the efficiency of this technique and a happier patient.
The ultimate goal of outpatient cataract surgery is less intervention and better visual results. This approach offers the greatest opportunity for the optimum refractive outcome.