The most recently updated Whitestar Signature Phacoemulsification System (Abbott Medical Optics Inc., Santa Ana, California), is one of the most advanced machines for performing phacoemulsification. Its power delivery and enhanced fluidics also make it one of the safest machines available. We recently worked with Daniel Mojon, MD, of Switzerland, to compile a book on minimally invasive eye surgery. This article is a summary of our cataract phaco technique using the Whitestar Signature platform, which we also describe in greater detail in the book.
INCISIONS
Incisions are made in the corneal plane. Coaxial phaco
incisions are 1.8 to 2.2 mm wide by 2 mm long. For biaxial
microincision phaco, incisions are at least 1 mm in length
but preferably 1.2 mm. The blade is applanated to the globe
just anterior to the conjunctival edge. The point of the
blade is tilted down to cut Descemet's membrane and is
once again applanated and moved into the incision at the
appropriate length (2 mm for coaxial phaco and 1.2 mm for
biaxial phaco). This produces a curvilinear architecture.1,2
Viscoat (Alcon Laboratories, Inc., Fort Worth, Texas) is injected through one of the sideport incisions into the distal chamber angle. The expanding wave of ophthalmic viscosurgical device (OVD) forces residual anesthetic solution, air, and aqueous humor out of the injection incision, which results in a stiff anterior chamber (Figure 1). In this way, the incision is constructed more accurately and reproducibly because the eye cannot distort unpredictably, as a soft eye generally does during incision construction. After a capsulorrhexis is created utilizing a microincision capsulorrhexis forceps through a sideport incision, we perform gentle cortical cleaving hydrodissection.3 A small capsulorrhexis (5 to 5.5 mm) optimizes the procedure, and a large anterior capsular flap makes this type of hydrodissection easier to perform. If the nuclear-cortical complex can be rotated by the cannula, then adequate hydrodissection has been achieved.
Next, we perform hydrodelineation3,4 to separate the endonucleus from the epinucleus and facilitate independent mobilization of the two layers. Hydrodelineation reduces the size of the nucleus that has to be mobilized through disassembly and emulsification, thereby reducing the amount of energy into the eye. This allows shallower and less peripheral grooving and smaller, more easily mobilized quadrants after cracking or chopping. When hydrodelineation is performed properly, a circumferential golden ring will outline the cleavage between the epinucleus and the endonucleus (Figure 2).
CHOPPING
We prefer a chopping technique in almost all cases. We
can disassemble the nucleus mainly with mechanical forces
by embedding the tip with vacuum and using minimal
amounts of ultrasound energy. We use a 30° bevel-down,
20-gauge phacoemulsification tip with the Signature platform.
Horizontal chopping. We prefer horizontal chopping for grades 1 to 2.5 nuclear densities because it stabilizes the endonucleus during disassembly. The irrigating chopper is inserted before the phaco needle, which slips into the slit incisions more easily when inserted bevel-down. When the leading edge of the bevel touches the endothelium at the internal lip of the incision, the phaco needle is rotated bevelup so that it enters the incision without tearing Descemet's membrane. It is then rotated bevel-down again. The chopper touches the center of the endonucleus with the vertical portion of the instrument and is pushed toward the golden ring distal to the phaco incision. Once the phaco needle is embedded 2 to 3 mm deep, we pull the chop instrument toward the side of the phaco needle to score the nucleus. We then move the phaco needle up and to the right while bringing the chop instrument left and slightly down. This allows complete fracture of the endonucleus through its floor, which creates two heminuclei (Figure 3). We then rotate the heminucleus clockwise and trap it between the chop instrument and the phaco needle, score, and chop it in the same way. We then mobilize the quadrants by occluding the bevel-down tip from above. The residual heminucleus is rotated to the distal periphery, stabilized, scored, and chopped. The last two quadrants are mobilized in the same manner (Figure 4).
Vertical chopping. This technique is done slightly differently. The bevel-down tip is buried in the endonucleus with sufficient lollipopping so that the nucleus is stable. Vacuum assists in this maneuver. We do not push down on the endonucleus as we are embedding the tip but allow phaco energy and vacuum to both drive the tip into the endonucleus and pull the endonucleus up toward the phaco tip— once again avoiding downward force on the capsule and the zonular apparatus. Once the phaco needle is embedded approximately 2.5 to 3 mm in the nucleus, we lift the phaco needle up and pull it to the right while pulling the slightly embedded chop instrument diagonally to the left and downward to avoid any force on the capsule or zonular apparatus. After the endonucleus is split into two heminuclei, we rotate them 90° and chop the second heminucleus; if it is a very hard endonucleus, we subdivide the quadrants further so that we end up with bite-sized pieces.
Hard cataract. We break apart the endonucleus into a sufficient number of small, pie-shaped segments before we mobilize those segments. Mobilization is achieved by bringing the phaco needle bevel-down on top of the segment, occluding the tip, and using vacuum and bursts of ultrasound to consume the segment as it moves up into the tip.
Soft cataract. We do cortical cleaving hydrodissection and hydrodelineation and then hydroexpress the lens into the plane of the capsulorrhexis. With the bevel of the phaco needle sideways (facing the equator of the lens), we carousel the endonucleus in the plane of the capsulorrhexis until it is completely evacuated. The irrigating handpiece is held above the endonucleus to prevent contact between the spinning endonucleus and the corneal endothelium while maintaining the endonucleus in the capsulorrhexis plane.5
Biaxial phaco. We believe that biaxial is less invasive because it gives us fluidic advantages that are unachievable with coaxial. Specifically, through the separation of infusion from aspiration and ultrasound energy, all of the fluid is entering through one side of the eye and exiting through the other. This eliminates competing currents at the phaco tip and enhances chamber stability. If the capsule does become torn, the circulating fluid in the anterior chamber allows us to reach into the posterior chamber with an unsleeved tip and mobilize nuclear material. Conversely, the fluid coming from the sleeve surrounding a coaxial tip would drive nuclear material into the vitreous body.
It is important to use ultrasound power modulation because this dramatically reduces the amount of phaco energy in the eye and achieves cold phacoemulsification and the ability to do biaxial phacoemulsification with an unsleeved tip.6,7
CORTICAL CLEAN-UP
It is more common to find residual cortex with smaller gauge phaco tips. We sweep the cortical aspirator circumferentially around the capsulorrhexis (port facing the fornix of the capsule) and draw out the remaining fragments. Because the connections to the capsule have previously been lysed by cortical cleaving hydrodissection, we rarely need to strip cortex centrally. After the epinucleus and cortex have been removed and the posterior capsule polished with the silicone-covered sleeve of the aspiration handpiece (port up, with minimal or no aspiration), we fill the posterior capsule and the anterior chamber with ProVisc (Alcon Laboratories, Inc.). We do not polish the undersurface of the posterior capsule because this may be associated with higher levels of posterior capsulotomy.8,9
IOL IMPLANTATION AND STROMAL
HYDRATION
We prefer cartridge injection rather than folding forceps
for IOL implantation. It is important not to tear
the incision by trying to inject a lens into a smaller incision
than can accommodate it. Tearing will compromise
the sealing capacity of the wound. OVD removal is
accomplished with biaxial irrigation and aspiration handpieces (Duet Bimanual System; MicroSurgical
Technology, Inc., Redmond, Washington). We routinely
lift the IOL and place the aspirator (port up) under the
lens to get all of the OVD out of the bag from under
the optic. We hydrate all incisions10 to cause the stroma
to swell. We test all incisions with fluorescein to make
sure that they are sealed. If they are not sealed, we place
a single 10-0 nylon stitch.
I. Howard Fine, MD, is a Clinical Professor of Ophthalmology at the Casey Eye Institute, Oregon Health & Science University and is in private practice at Drs. Fine, Hoffman, & Packer LLC, Eugene, Oregon. Dr. Fine states that he is a paid consultant to Abbott Medical Optics Inc. He is a member of the CRST Europe Global Advisory Board. Dr. Fine may be reached at tel: +1 541 687 2110; e-mail: hfine@finemd.com.
Richard S. Hoffman, MD, is a Clinical Associate Professor of Ophthalmology at the Casey Eye Institute, Oregon Health & Science University, and is in private practice at Drs. Fine, Hoffman, & Packer, LLC, Eugene, Oregon. He states that he has no financial interest in the products or companies mentioned. Dr. Hoffman may be reached at tel: +1 541 687 2110; e-mail: rshoffman@finemd.com.
Mark Packer, MD, FACS, is a Clinical Associate Professor at the Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, and is in private practice at Drs. Fine, Hoffman & Packer, LLC, Eugene, Oregon. He states that he is a paid consultant to Abbott Medical Optics Inc., Advanced Vision Science, Bausch + Lomb, Celgene Corp., General Electric Company, Haag-Streit USA, and Rayner Intraocular Lenses, Inc., and holds stock options with Surgiview LLC, Transcend Medical, Inc., TrueVision Systems, Inc., Visiogen, Inc, and WaveTec Vision Systems. Dr. Packer may be reached at tel: +1 541 6872110; e-mail: mpacker@finemd.com.
