54 Microincision Phaco Surgery This chapter discusses routine microincision phaco surgery, which is the technique I currently perform. The discussion focuses on subtle points of the procedure that facilitate performing it, help avoid complications, and lead to successful and reproducible outcomes. I also review several common difficult situations faced by today’s implant surgeon, and discuss the principles and pearls that can facilitate dealing with these trying situations. When one observes true masters of phacoemulsification perform surgery, one cannot help but wonder, as I have, how it is that they achieve seemingly flawless results with such aplomb and ease. The answer, of course, is to be found in their attention to detail. The following discussion addresses the basic components of the procedure, providing details that I have learned from my teachers that facilitate performing the procedure and avoiding complications. The advantages of noninjection anesthesia to both patient and surgeon are well recognized. A common denominator for success, for both the novice as well as experienced surgeon, is proper patient selection. In fact, after many years of performing topical (and later intracameral) anesthesia, my percentage of noninjection cases began to approach the 98% level; however, I realized that my surgery had become less enjoyable and more trying for both me and my patients. This was due to “pushing the envelope,” as I was operating on many patients who were simply not appropriate candidates. By becoming more selective (and returning to more frequent use of injection anesthesia), I was able to be more efficient, and both my patient and I enjoyed a better experience. One’s selection criteria will vary based on experience and case variety, but I base my decision on a few simple elements of the preoperative exam and how the patient reacts to them. If the patient exhibits unusual blepharospasm or a marked Bell’s phenomenon during biomicroscopy and, in particular, indirect ophthalmoscopy, the patient is almost always deemed an inappropriate candidate for topical anesthesia. I further empower my surgical assistants who perform our biometric measurements to designate on the chart that the patient exhibited poor cooperation, and I adhere to their recommendations. Also, once in the operating room, if the nursing or anesthesia personnel voice doubt about the patient’s ability to cooperate, then we convert to some form of injection anesthesia. I have rarely regretted opting for a deeper anesthetic, but I have often regretted not doing so. When utilizing noninjection anesthesia, draping of the patient’s eyelids may become more challenging. I am a firm believer in compulsively sequestering the entire lid margin under the protection of a plastic drape to enhance “barrier” prophylaxis against infection. This requires extra effort when orbicularis function is intact. If the patient shows an unusual reaction to draping and the insertion of the speculum, it is the final chance to “bale out” by converting to injection anesthesia. Surprisingly, it actually requires very little topical anesthesia to adequately anesthetize an eye for intraocular surgery. I have found that nearly any common topical anesthetic agent will suffice, but the important point is not to overdo it. Administering a single drop prior to instillation of the dilating regimen, followed by a drop at the time of the prep, and then again immediately prior to commencing surgery, is generally more than adequate. If instilled too early or too often, despite insisting that patients keep their eyes closed, troublesome drying and a punctate surface keratopathy may result; most patient’s anxious and inquisitive state prior to surgery may cause them to gaze about the room, curious about the unfamiliar situation and surroundings. This may potentially compromise intraoperative visualization as well as increase postoperative discomfort. Topical gel anesthetics are also useful to prolong the anesthetic effect and aid in lubrication throughout the procedure. Many surgeons further supplement the topical agent through the use of an intracameral agent such as 1% sterile nonpreserved lidocaine. Another important clinical point is that the sensation that is most profound to the patient while under anesthesia involves stretching of the zonular apparatus. This is most likely to occur in high myopes and in patients who have had previous vitreous surgery. I find that noninjection anesthesia may still be used in these cases, but great care must be taken to gradually deepen the anterior chamber (AC), trying to avoid a sudden and severe stretch placed upon the zonules. Even in routine cases, patients may note some sensation when the irrigation and aspiration (I/A) is first placed into the eye following phacoemulsification. It is at this point during the procedure that the greatest hydrostatic tension is placed on the zonules. Therefore, I find it helpful to instill additional intracameral anesthesia during the exchange of the phaco to I/A instrumentation. The increase in AC volume due to the additional anesthetic and balanced salt solution (BSS) also helps to blunt the sudden pressure and volume rise that occurs upon reentering the eye. The surgeon should be aware of an interesting phenomenon that occurs in an eye that has previously undergone vitrectomy surgery. Shortly after adopting noninjection anesthesia, I was surprised to learn that in the post-vitrectomized state, intracameral anesthesia can very efficiently diffuse back to the retina and cause amaurosis despite an intact posterior capsule. Similarly, if a capsular rent occurs intraoperatively, and particularly if a vitrectomy is required, diffusion may again occur. Patients should be warned of a temporary diminution or loss of their vision. To my knowledge, no untoward sequelae have ever been documented following this phenomenon. In fact, I have personally employed topical and intracameral anesthesia in planned posterior vitrectomy cases. It is well recognized that one of the greatest advantages of the temporal approach is better access to the globe and improved exposure and intraoperative visualization. In fact, once surgeons who had previously utilized a superior approach have accomplished this somewhat challenging transposition, they will likely find that they dislike working from any other approach. In transitioning to the temporal position, several challenges arise: positioning one’s knees under the operating table, acquiring adequate wrist support, and shifting personnel and equipment into a new workable configuration. Once these hurdles are met, several additional subtle challenges may be recognized; for example, access to the side-port incision, which is now either at the 6 or 12 o’clock position, may be awkward, especially in patients with deeply set eyes. Several specialized specula have been designed to aid with the temporal approach. I use a modification of the classic Kratz-Barraquer wire lid speculum, which works well in most patients. It is made of a heavier gauge metal, making it more resistant to blepharospasm. In addition, the temporal aspect is angulated posteriorly, over the lateral canthus, such that it is out of the way of incoming instrumentation. I also use a similar design with a locking mechanism for those patients who are truly squeezers; however, if I have adhered to the preoperative selection criteria, this situation rarely arises because the squeezing patient should have been scheduled to receive injection anesthesia. Another important issue is fixation of the globe, particularly under noninjection anesthesia and when utilizing a clear corneal incision. My preference is to use a modified Fine-Thornton fixation ring. The upper surface has 10-degree markings to aid in placement of limbal relaxing incisions, and the undersurface of the ring has been highly polished to minimize conjunctival trauma. Mild downward pressure of the ring is typically all that is necessary to stabilize the globe. Other surgeons find it helpful to place an instrument through the side port to fixate the globe, or simply using a gloved finger placed over the bulbar surface may gently stabilize the eye. As noted above, a potentially challenging peculiarity of the temporal approach is access to the side-port incision. When operating superiorly there is typically unencumbered access to the paracentesis (at the 3 or 9 o’clock position). Now, however, access to the 6 or 12 o’clock position may be hampered by either the lid speculum or the orbital rim, particularly in deep-set eyes or in individuals with narrow palpebral fissures. For this reason, additional modifications to conventional instrumentation may be of help. These include nuclear manipulators that have a more vertical angulation to better fit down into a deep-set eye. Also, modified irrigating cannulae with shortened tips facilitate placement through side-port incisions. Always important is the detail of patient positioning. One must ensure that the patient’s neck is neither hyper- nor hypoextended (the elderly tend toward the former, and younger patients toward the latter). I encourage our operating room personnel to labor over this detail, as proper and consistent positioning leads to more efficient and reproducible surgery. This holds true also for the surgeon’s chair, pedals, and microscope. I further employ a subtle but helpful maneuver taught to me by Bruce Wallace, a cataract surgeon in Alexandria, Louisiana. By slightly tilting the patient’s head temporally toward the side that the surgeon is sitting on, there is significant improvement of visualization as well as more ergonomic positioning of the microscope. There is a tendency during surgery for the patient to move away from the surgeon, so we routinely place a very light strip of tape over the patient’s forehead as a friendly reminder to maintain the desired position. Lastly, to improve efficiency and logistics in the operating room, an attempt is made to schedule all right eyes together and similarly left eyes are grouped together to avoid having to make unnecessary changes to the positioning of equipment and instrumentation. One need not extol the many virtues and efficiency of clear corneal incisions; however, studies and early experience provided evidence that there may be an increased tendency toward wound leakage and a higher risk for infection with this approach, particularly during one’s learning curve. Through the work of Paul Ernest and others,1–3 it has become clear that the key to creating a wound with sufficient integrity to avoid leakage is to strive toward a “square” architecture, such that the incision’s depth approximates its width. With today’s smaller incision sizes, such wound construction is readily accomplished. Another point to consider is proper sizing of an incision in relation to the phaco needle and sleeve combination that is used, as this is of paramount importance to achieve optimal fluidics.4 Too tight an incision risks impeded infusion with loss of AC volume, or worse yet, a corneoscleral burn5; however, the more common tendency is to use an incision size that is too large and therefore leads to unnecessary leakage and chamber instability. It should be noted that a grooved incision tends to gape more and will therefore behave as if it were a slightly larger incision, and tends to induce slightly more wound flattening and hence surgically induced astigmatism. Many surgeons ignore the importance of the side-port paracentesis incision. Most manipulators will pass through an incision of 0.5 to 0.7 mm, thus making the standard 1-mm side-port incision too large and, hence, leaky. The key to performing a consistent capsulorrhexis is maintenance of a deep AC. Fortunately, today’s microincisions help to inhibit loss of viscoelastic and aid in retention of AC depth. In difficult cases, such as intraoperative floppy iris syndrome (IFIS) or an unusually shallow AC, performing the rhexis through a separate smaller incision may be helpful, and proper use of viscoelastics is fundamental in promoting and maintaining chamber depth and iris stability. Though my preference is to use actuating micro-capsulorrhexis forceps in most cases, yet another trick in difficult eyes is to create the rhexis through a small paracentesis utilizing a cystotome, placed upon the a viscoelastic syringe, such that the chamber may be immediately deepened should shallowing occur or excursion of the tear be encountered. My standard incision is placed temporally, is single plane (unless a relaxing incision is needed for preexisting astigmatism), measures 1.8 mm to correspond to my preferred micro-coaxial phaco tip and sleeve combination, and is created at the posteriormost extent of the limbus. As such it typically produces a trace amount of bleeding. I find that this approach seals consistently well. In performing the rhexis through this microincision, I have found that the Seibel micro-actuating forceps (Micro-Surgical Technologies [MST], Redmond, WA) are very useful. The tear is begun by pinching the anterior capsule centrally, and is immediately followed by a circumlinear movement clockwise, such that the flap is folded over upon itself and advanced using a shearing rather than a stretching force. Following completion of the tear, the capsular segment is removed from the AC to ensure that the rhexis has been completed 360 degrees. Additionally, when removing the torn capsule, gentle pressure on the posterior lip of the incision enables decompression of the AC, helping prevent overpressurization during subsequent hydrodissection. This decompression should be performed slowly and gently in cases of IFIS. Thorough hydrodissection is important to ensure trouble-free phacoemulsification for most forms of intracapsular surgery. I find it helpful to confirm adequate hydrodissection by visualizing free and easy rotation of the lens within the capsular bag before proceeding with lens removal. I personally prefer the technique of cortical cleaving hydrodissection as taught by Howard Fine, a surgeon in Eugene, Oregon: without irrigation, a flattened hydrodissection tip is placed under the anterior capsular leaflet and injection is gently performed in one or two locations. After each injection the lens is lightly balloted in a posterior direction, causing the injected fluid to pass in a wave-like fashion around the equatorial region, lysing cortical capsular adhesions. Hydrodelineation, on the other hand, may be considered an optional step by some surgeons, but I personally employ this maneuver in all endocapsular techniques. This hydro-maneuver enables one to work within the safe confines of the epinuclear shell, affording better capsular protection. Also, with modern chopping techniques, I find it easier to remove the chopped segments of the hydrodelineated nucleus, as they are smaller and easier to purchase. Some surgeons may initially struggle with removal of the outer epinucleus. This is in actuality easily accomplished, again as taught by Fine, by simply trimming the epinuclear bowl in all four quadrants using aspiration and then allowing it to collapse and flip in upon itself. There are now many variations on the original Nagahara phaco chop technique, originally described in 1993.6 My personal preference is for a technique that was originally referred to as “Quick Chop,” a term coined by David Dillman (Danville, IL), and is now more widely referred to as vertical chop. This technique, with slight variations, was described contemporaneously by several surgeons, including Thomas Neuhann (Germany),7 Vladimir Pfeifer (Slovenia),8 Abhay Vasavada (India),9 and Hideharu Fukasaku (Japan). Several key points pertain to all phaco chop techniques. First, one should get in the habit of exposing more of the phaco needle (beyond the leading edge of the silicone sleeve) to enable a deeper purchase of the nucleus. I personally find that a 15- to 30-degree bevel tip is optimal. After chopping, the purchase of cleaved segments may be aided by tipping up the central tip or “apex” of the chopped segment anteriorly, and then sliding the phaco tip beneath the undersurface, rather than allowing the segment to tumble forward. This may be facilitated by using the manipulator to push the chopped segment out toward the equator of the bag, which in turn causes the posterior apical aspect to slide upward. If the phaco needle or chopper is positioned too high, it will skim over the surface of the nucleus. If the chopper is inadvertently placed over the capsular bag, it will tear the bag or the zonule (Fig. 54.1). Another helpful hint involves rotation of the bevel such that optimal apposition occurs with chopped segments. This requires rotation of the phaco instrument along its long axis, and will in essence create a 0-degree tip when the bevel is placed parallel to the presenting surface or facet of the chopped segment. Occlusion is thus maximized. Perhaps the most important point in all disassembly techniques involves the discipline to ensure that each successive cleavage plane is complete in its separation from one pole of the nucleus to the other and from anterior to posterior. This may require placement of the instruments deeply into the fault line that has been created, and then lateral separation in several different locations to ensure that the division plane propagates entirely through the posterior nuclear plate. Complete separation is confirmed by visualization of the red reflex. This separation should occur on each successive chop and division, or the result will be multiple, partly separated, peripheral segments connected centrally and posteriorly—a conformation that resembles a tulip or garlic clove. One of the most common complaints voiced during the transition to the traditional Nagahara phaco chop technique involves placement of the chop instrument around the edge of the nucleus in the capsular bag periphery. Upon examination of the bag anatomy and curvature and design of most choppers, it becomes apparent that this potentially dangerous maneuver may be safely performed by carefully angulating the instrument such that the proximal handle of the instrument is brought back toward the surgeon, causing the distal tip of the chop instrument to assume a plane parallel to the iris (Fig. 54.2a). At this point, excursion out under the anterior capsule to the periphery may be safely made without snagging the capsule or prematurely engaging the nucleus. Once out and around the endonucleus, the handle of the instrument is brought upright once again, thus causing the distal tip to pass around the equator of the lens (Fig. 54.2b). The chop can then be made against the impaled phaco tip. Alternatively, this maneuver may be obviated by adopting the vertical chop technique described above. Again, in this approach the chop instrument is placed just in front of or to the side of the centrally impaled phaco needle. The chop instrument is pressed downward, toward the optic nerve, and then outward (or laterally). The phaco tip, impaled in the bulk of the nucleus, is slightly elevated, providing counterforce to the downward force of the vertical chopper (Fig. 54.3). One subtle key with these maneuvers is to use the side-port incision as a fulcrum such that the heel of the instrument—that portion outside of the incision—elevates as the distal tip passes downward into the lens. Otherwise, depression of the paracentesis site will cause a distorted view of the AC. Additionally, a more pointed or faceted tip, as opposed to the blunted tip designed for safety during traditional phaco chop, is best for this technique. Preplacement of a groove or central sculpting can be quite helpful to the surgeon making the transition from a standard divide-and-conquer approach to a chopping technique. The veteran phaco chop surgeon generally utilizes only central debulking when dealing with extremely dense nuclear cataracts. This enables the initial chop to be performed on less nuclear bulk, thus creating more space and requiring less physical energy to create the initial cleavage plane. Many surgeons continue to utilize bare-metal I&A instrumentation without a silicone sleeve and therefore incur unnecessary incisional leakage. This leads to collapse of the capsular fornix, thereby creating greater difficulty accessing and removing cortical material. I find that a 45-degree angled diamond-dusted tip, used with an appropriate incision-sized silicone sleeve, provides excellent access to 360 degrees of the capsular bag. Rarely, recalcitrant, usually subincisional, cortex may remain, and I use a simple manual maneuver to remove this material. Viscoelastic is first used to push the posterior capsule downward in the area of the cortex. A double-bent 27-gauge cannula attached to a tuberculin (TB) syringe half filled with BSS is then placed through a side-port incision. The double-bent cannula can easily reach the subincisional area. Light pressure on the plunger of the syringe enables delicate loosening of the cortex by irrigation, which is then followed by purchase and stripping from the fornix by lightly pulling back on the plunger and aspirating. The cortex is then brought up and into the AC, where removal may then be completed with the I/A tip. This same technique is used to remove cortex when faced with a breach in the posterior capsule or when dealing with weakened zonules (see below).
Routine Phaco Surgery
Anesthesia
Noninjection Anesthesia: Selection Criteria
Anesthetic Timing and Application
Exposure and Instrumentation
Incision
Capsulorrhexis
Hydrosteps
Phacoemulsification
Irrigation and Aspiration
Ento Key
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