Bimanual Microincision Phaco
We began bimanual microincision phacoemulsification more than 5 years ago in anticipation of being in the first wave of US microincision IOL investigators. We soon recognized that bimanual microincision phaco is a superior procedure, and therefore, we have limited our cataract surgeries and refractive lens exchanges to this technique over the past 5 years.
The first person to perform bimanual microincision phacoemulsification, in a way that is reminiscent of what we currently do, is Steve Shearing, MD,1 of Las Vegas. Subsequently, Tsutomu Hara, MD,2 from Japan; Amar Agarwal, MS, FRCS, FRCOphth,3 from India; Hiroshi Tseunoka, MD,4 from Japan; Jorge L. Alió, MD,5 from Spain; Randall J. Olson, MD,6 from Utah; David F. Chang, MD,7 from California; as well as our practice8 have added to the discussion of the value of this technique.
Of course, bimanual I/A of the cortex is known to be advantageous. Bimanual microincision phacoemulsification is better than standard coaxial phacoemulsification, because it involves smaller—and possibly safer—incisions. It is closer to the ideal procedure (ie, a completely closed system) in that there is dramatic reduction of fluid through the eye. With bimanual microincision phaco, we have improved followability: We may manipulate tissue with incoming fluid, and we have a more stable chamber, because the fluid enters through one side of the eye and leaves through the opposite side. Therefore, we do not have competing fluid currents around the phaco needle.
The improvement in fluidics is especially advantageous in difficult and challenging cases. In high myopia, we leave the irrigating handpiece within the eye throughout the case, as we remove the phaco needle and add viscoelastic, so that we never trampoline the vitreous face. This may contribute to a lower incidence of retinal detachment in patients with high myopia. Posterior polar cataracts are also stabilized by better fluidics, resulting in a less likely loss of nuclear material into the vitreous, or pulling the plug out of the compromised posterior capsule. Similarly, in the presence of zonular dialyses, subluxed lenses, or posterior capsule rupture, separating infusion from aspiration and phacoemulsification in bimanual microincision phaco allows these cases to be completed without extending the damage.
Bimanual microincision phacoemulsification is advantageous when intraoperative floppy iris syndrome (IFIS) occurs. We can, in many cases, hydroexpress the cataract out of the capsular bag and carousel the endonucleus in the plane of the capsulorrhexis. Therefore the epinucleus holds the iris back and keeps the irrigator high in the anterior chamber, which further tamponades the iris and keeps it from becoming floppy. As long as we irrigate above the iris, it will not billow. In those IFIS cases where we cannot hydroexpress the lens, we dilate the pupil widely with Healon 5 (Advanced Medical Optics, Inc., Santa Ana, California), do our hydrosteps, and then perform one endolenticular chop. Next, we bring the nuclear material up to the irrigating chopper, which is kept above the iris, for disassembly and mobilization. Very frequently, by restricting ourselves to foot position three in occlusion or foot position one with a clearance of occlusion, the Healon 5 can remain in the eye, keeping the pupil dilated. Additionally, the anterior location of the irrigator tamponades the iris. After epinucleus removal, the pupil tends to constrict, however, we redilate it with Healon 5. By keeping the aspiration tip in occlusion, we go circumferentially around the capsulorrhexis, mobilizing cortex from the capsular fornices without bringing it out of the eye. Maintaining occlusion of the tip immobilizes Healon 5, thus allowing the pupil to remain dilated. After the cortex has been removed from the fornix, we then remove it from the eye.
During refractive lens exchange, we have found that hydroexpressing the lens into the plane of the capsulorrhexis and carouselling it allows us to remove the lens in the safest position in the eye. We do not use phacoemulsification energy, but fluidics alone.8 These examples demonstrate the advantages of separating irrigation from aspiration and phaco that make bimanual microincision phacoemulsification the preferential technique for difficult and challenging cases.
We are frequently confronted by criticism; some surgeons feel that this technique is not worthwhile, because we still have to make an incision—between our two microincisions—for IOL implantation. This is reminiscent of early phacoemulsification criticism in the 1980s, before foldable IOLs were available, and the phaco incision had to be enlarged to implant an IOL. We persisted in our belief that phacoemulsification was a better procedure than extracapsular cataract extraction. In a similar manner, we believe that bimanual microincision surgery is a better procedure, even in the absence of an IOL insertable through these microincisions.
We strongly prefer diamond knives, because the incisions are reproducible, and they do not stretch tissue. We use the Fine-Paratrap blade (Mastel Precision, Inc., Rapid City, South Dakota) (Figure 1); the 3D Blade (Rhein Medical, Inc., Tampa, Florida); and the Packer Bimanual Phaco Diamond Knife (ASICO, Westmont, Illinois). We also use metal blades including one from the Duet Bimanual set (Microsurgical Technology, Redmond, Washington). We routinely separate our microincisions by 60º to 90º. We like them to be approximately 1.5 mm long; our strong preference for trapezoidal blades is due to the ease through which we rotate instruments within the incision without being oar-locked. The incisions are 1.1 mm internally and 1.3 mm externally.
Following incision construction, we exchange aqueous for viscoelastic (Viscoat; Alcon Laboratories, Inc., Fort Worth, Texas) by injecting viscoelastic into the distal angle through one of the microincisions. This allows for (1) extrusion of aqueous and (2) a stable anterior chamber. We then perform a capsulorrhexis with one of several instruments: Fine-Hoffman Capsulorrhexis forceps (Microsurgical Technology) (Figure 2); Fine-Ikeda forceps (ASICO); or Fine Capsulorrhexis forceps (Katena Products, Inc., Denville, New Jersey). Each instrument allows us to make a very precise capsulorrhexis through a 1-mm incision.
It is interesting that the size and shape of these capsulorrhexes are more accurate compared with traditional capsulorrhexis forceps through a 2.5-mm incision. We believe that this is because one cannot use the wrist when making a capsulorrhexis through a microincision—we are limited to finger movements. We aim for a round capsulorrhexis diameter between 4.5 mm and 5.5 mm.
We perform cortical cleaving hydrodissection in 100% of our cases.9 Removing viscoelastic is not necessary when injecting through microincisions, because some posterior pressure on the incision will allow egress of viscoelastic during the cortical cleaving hydrostep. Following cortical cleaving hydrodissection, we spin the lens (to be sure that the cortical connections to the capsule have been severed) and perform two hydrodelineation injections, as we have previously described.9 We then rock the nucleus from side-to-side to be sure that we have severed the epinuclear-endonuclear connections.
We allow for continuous flow throughout the procedure, including chopper insertion. The irrigating chopper is held vertically, and the tip is inserted beyond the internal lip of the incision. The handle is rotated horizontally, and the open end of the chopper is brought into the eye to prevent snagging of Descemet's membrane. For horizontal chopping maneuvers, we prefer choppers that we designed with Microsurgical Technology, all of which are front irrigating. The anterior chamber deepens as soon as the open end touches the microincision, thus avoiding injury to intraocular structures. Also, irrigation remains constant in direction with instrument rotation during the operation. These maneuvers are exactly the same as with an irrigating instrument that we have previously described on the use of power modulations and the choo-choo chop and flip technique.10
We use horizontal chopping for softer nuclei (ie, grades 1 or 2+), and vertical chopping for nuclei of grades 3 and 4+. We have designed chopping instruments with Microsurgical Technology, Katena, Rhein Medical, Inc., and ASICO. The choppers produced by Microsurgical Technology are thin-walled and short; there is a decreased resistance to flow, and they are bent slightly so microincision placements, forcing us to work over the brow and cheek, do not necessitate upward pull on our instrument to get over the brow or cheek.
We perform bimanual microincision phacoemulsification with most machines available in United States. The major difference between coaxial phacoemulsification and bimanual microincision phacoemulsification resides in how the instruments are coordinated. In coaxial phacoemulsification, we tend to use the chopper (ie, our second-hand instrument) very close to or a little above or below the phaco tip, however, most frequently we use it directly in front of the tip. We must be careful in bimanual microincision phacoemulsification to not irrigate material purchased at the phaco tip with the incoming stream of fluid. As a result, we work with our phaco tip slightly below and behind the chopper, approaching it from below and behind as we need to use the chopper.
For horizontal chopping, we touch the center of the endonucleus, and with the vertical element of the chop instrument in a vertical orientation, slide it to the distal left periphery until it drops into the golden ring created by hydrodelineation. We then lift the endonucleus up and toward the incision. Using power modulations and high vacuum, we (1) imbed the phaco tip, (2) draw the chop instrument toward the side of the phaco tip, and (4) separate our hands with a little downward force on the chop instrument and an upward force on the phaco tip. This results in a complete division of the endonucleus to hemi-nuclei. We then rotate clockwise, and in a similar manner, chop the second hemi-nucleus. After the second chop, a pie-shaped segment is attached to the phaco tip in its bevel-down configuration. We can mobilize it, if it is soft enough, or chop it a second time to reduce the size of the pie-shaped segment.
For vertical chopping, we imbed the phaco tip and then drive the vertical chop instrument diagonally downward above the tip (Figure 3). We separate our hands with an upward movement of the phaco tip and a downward diagonal movement of the chop instrument (Figure 4), usually resulting in an immediate division of the endonucleus into two. We then rotate it to purchase the largest hemi-nucleus for rechopping, and, once again with the second chop, we have a pie-shaped segment attached to the phaco tip that can be mobilized or chopped an additional time (Figure 5).
With respect to maintaining a stable anterior chamber, we have not had any problems with these instruments or techniques. We found that our chamber is more stable versus coaxial phaco. If a hole is blown into the posterior capsule with the phaco tip, we may continue the procedure by maintaining irrigation high in the anterior chamber and reaching into the capsular bag to mobilize nuclear material. This is impossible with coaxial phacoemulsification, because as we brought the phaco tip down, a forceful stream of fluid with fluctuating direction would enter the capsular bag and almost certainly extend any preexisting tear.
We chop the endonucleus (as previously described) and mobilize epinucleus at the level of the capsulorrhexis. We prefer straight 30º-phacoemulsification tips used bevel-down. The bevel-down configuration has three distinct advantages. (1) The approach to the endonucleus through a clear corneal incision is approximately 30º. With the 30º bevel-down tip, as soon as we touch the endonucleus, we can evoke vacuum to help bury the tip and stabilize the nuclear material. (2) Ultrasound and cavitational energy is directed toward the nucleus, rather than toward the corneal endothelium or the trabecular meshwork. (3) We can mobilize nuclear material up from the level of the capsulorrhexis, rather than having to go deeply into the endolenticular space to achieve mobilization of these pie-shaped segments.
When the endonucleus is removed, we turn the chop element on our chopper horizontally and rotate the phacoemulsification needle to a bevel up position to mobilize the epinucleus. This has previously been described.10 We rotate the epinucleus with the phaco tip in zero foot position, rather than with the chop instrument, to provide added safety. This is analogous to the way we rotated nuclear material in the days of one-handed phacoemulsification, with the phaco tip in either foot position zero or foot position one.10 After we trim and flip the epinucleus, we remove our instruments, and a straight irrigating handpiece enters through the left incision and an aspirating instrument through the right. We prefer the Microsurgical Technology bimanual irrigation and silicone-coated aspiration instrumentation; it is important that the port be highly polished. We usually use a 0.2-mm aspiration port, because most of the cortex is removed following cortical cleaving hydrodissection, and wispy strands that occlude a 0.2-mm aspiration tip much better than a 0.3-mm aspiration tip are still left. After polishing the posterior capsule and removing residual cortex, we then remove the aspirator and inject viscoelastic prior to removing the irrigator.
We can then stromally hydrate the two side-port incisions and make an incision between them for IOL implantation. We do not enlarge one microincision, because the manipulation through these incisions somewhat distorts them, and they seal less well if we enlarge them. For most IOLs, we use a 2.7- to 2.8-mm wide incision that is 2 mm long. For single-piece acrylic IOLs, we use a 2.2-mm wide incision. We most frequently use the 3D diamond blade trapezoidal knife (Rhein Medical, Inc.). After IOL implantation, we usually perform coaxial removal of viscoelastic in front of and behind the IOL, followed by stromal hydration on both side-port incisions as well as the implantation incision. We continue to test all incisions with fluorescein dye and pressure on the incision to document sealing after stromal hydration and reconstitution of the anterior chamber with Miochol (Novartis Pharmaceutical, Basel, Switzerland) to bring the pupil down and allow for immediate clear vision.
We believe that bimanual microincision phacoemulsification represents the future of cataract surgery and refractive lens exchange. Soon, small incision lenses that go through these microincisions will be available, and the full promise of increasingly smaller incisions will be realized.
I. Howard Fine, MD, is Clinical Professor of Ophthalmology at the Casey Eye Institute, Oregon Health & Science University, and he is in private practice at Drs. Fine, Hoffman, & Packer, in Eugene, Oregon. Dr. Fine states that he is a consultant for Advanced Medical Optics, Inc. and Bausch & Lomb, Inc. Dr. Fine may be reached at +1 541 687 2110; hfine@finemd.com.
Richard S. Hoffman, MD, is Clinical Associate Professor of Ophthalmology at the Casey Eye Institute, Oregon Health & Science University, and he is in private practice at Drs. Fine, Hoffman, & Packer, in Eugene, Oregon. Dr. Hoffman states that he has no financial interest in the products or companies mentioned. Dr. Hoffman may be reached at +1 541 687 2110; rshoffman@finemd.com.
Mark Packer, MD, FACS, is Clinical Associate Professor of Ophthalmology at the Casey Eye Institute, Oregon Health & Science University, and he is in private practice at Drs. Fine, Hoffman, & Packer, in Eugene, Oregon. Dr. Packer states that he is a consultant for Advanced Medical Optics, Inc. and Bausch & Lomb, Inc. Dr. Packer may be reached at +1 541 687 2110; mpacker@finemd.com.
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