Ординатура / Офтальмология / Английские материалы / The Art of Phacoemulsification_Mehta, Alpar_2001

is placed in the side port incision and the eye reinflated so that it feels quite firm when the center of the cornea is pressed. If the wound is still leaking stromal hydration can be useful. The endothelial pump starts to work within a few minutes of the end of the procedure. The watertightness of the wound is tested by placing

a dry sponge posterior to the wound and pressing. It should remain dry. In the vast majority of cases a suture is not required because the tunnel wound

and its internal valve close satisfactorily. If the surgery has been complicated and the IOL has been inserted unfolded or when tested with a sponge the wound has not sealed properly a suture will be placed.

Suturing the Wound

Instruments Colibri toothed microsurgical forceps, micro needle holder, Alcon 10/0 nylon suture CU1 needle.

Technique With viscoelastic in the eye to retain its firmness, the lip of the wound is lifted with the Colibri forceps. A horizontal pass is made with the needle along the bed of the wound from right to left. The needle is now passed through the upper part of the tunnel from inside out. It is reinserted through the outside of the tunnel again and into the wound to create a horizontal mattress stitch. This is tied into the wound (Fig. 14.43) and the ends trimmed. No great tension is needed on the stitch as it generally is acting only to buttress the tunnel.

FINAL CONSIDERATIONS

The conjunctiva is picked up and cefuroxime is injected subconjunctivally. The drape is then removed and a shield placed over the eye.

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author’s technique was changed from those of his predecessors, above, to achieve 5 goals which the author felt were not adequately achieved with previous techniques:

•Permit all of the work to be done in the central 3 to 5 mm of the lens, thus making the technique safer, and directly applicable to small pupil phaco surgery.

•Divide the lens in a manner to minimize zonular stress, thus increasing safety, especially for cases of pseudoexfoliation, or postvitrectomy cataracts.

•Completely eliminate sculpting, which is inefficient and may cause excessive zonular stress, particularly in very dense nuclear cataracts.

•Reduce phaco time to a minimum, thus making the procedure more endothelial cell friendly.

•Make the procedure relatively independent of nuclear density, so that the surgeon does not have to significantly vary the approach to the lens from case to case, thus reducing complication rates.

Method

The technique is illustrated in Figures 15.1A to H, and a detailed description of issues pertinent to nuclear disassembly is given below. Preoperative patient preparation, anesthesia, incision, and other surgical steps are only mentioned where materially different in this procedure compared to other common cataract techniques.

Hydrodissection

Cortical cleaving hydrodissection is achieved, as taught by Fine,12 using balanced salt solution in a 6 cc syringe with a 27-gauge hockey stick cannula. Meticulous hydrodissection is essential to this technique, as frequent nuclear rotation is required. Consequently, the author usually does it twice: once injecting the balanced salt solution (BSS) under the nasal lip of the capsulorrhexis, and again under the temporal lip. He then checks for nuclear freedom by slight gentle nuclear rotation with the hockey stick cannula.

GETTING READY TO SLICE

In all chopping techniques, the anterior lens cortex can obstruct visibility and is gently phacoemulsified off by encircling the inside edge of the capsulorrhexis with the phaco before proceeding to slice and separate. This step also helps cortical removal because it creates an even frilly cortical edge at the capsulorrhexis margin which assists in the aspiration of any residual cortex. No phacoemulsification is done inside the eye until both the phaco tip and the Nagahara chopper (Asico #AE2515) are secure inside the anterior chamber (to stabilize the eye), and the phaco is run on I/A for a few seconds to clear some central viscoelastic, permitting free fluid flow.

The First Slice

The first slice is the most difficult and most critical. The Nagahara chopper tip is gently placed against the nucleus just inside the capsulorrhexis lip proximal to the incision, and the nucleus is nudged distally. The phaco tip, which is already

PHACO SLICE AND SEPARATE 157

Fig. 15.1E: The nucleus is rotated clockwise about 30 degrees, and a second slice is made in the distal nuclear half. In order to attain satisfactory depth with the phaco tip, it is often necessary to traverse part of the proximal nuclear half with the phaco, for the first two or three slices

Fig. 15.1F: The sliced piece is then separated from the remaining part of the distal heminucleus to achieve good cortical separation. The posterior capsule usually becomes visable with this maneuver, beginning with the second slice

Fig. 15.1G: The lens is again rotated and slicing and separating repeated. Removal of the nuclear pieces can be begun at any time. Sometimes it is easier to remove one of the first pieces to create working space, but sometimes, if the separations are more difficult to achieve, it is easier to slice up the entire nucleus before removing any piece

Fig. 15.1H: Usually the second, or later, piece of pie is removed first, because separations of the pie pieces becomes cleaner as the procedure progresses. Once a space is opened up, when a piece has been removed, the subsequent slices become easier, and are merely continued all around

158 THE ART OF PHACOEMULSIFICATION

in the eye, is now buried into the nucleus, aiming just to the right of and beyond (if the phaco is being held in the right hand) the geographic center of the nucleus (central in depth as well), making sure that the anterior surface of the phaco needle stops below the nuclear surface. In the author’s experience, this is optimally achieved with the phaco machine set on linear pulse, about 5 per second, with a 50% duty cycle. The vacuum is set at about 150 mm Hg using a peristaltic pump and standard sized needle (however the Alcon ABS smaller needles require vacuum of about 275 mm Hg). If the vacuum is set too high, the phaco will

tend to erode through the nucleus, rather than stabilizing it. It is easier to achieve nuclear stabilization if the silicone sleeve of the phaco needle is recessed from the tip 3 to 4 mm, rather than the more customary 2 to 3 mm, because it is not desirable for the irrigation port to enter the nuclear tunnel created by the phaco needle. Thirty, fifteen, or zero degree phaco needles may be used, with the author’s own preference being the 30 degree tip, because it is able to be easily occluded to achieve slicing, but the emulsification of the segment is not slowed as it is significantly with the steeper angled tips. Furthermore the 30 degree angulation of the needle aperture roughly equals the entry angle of the phaco needle into the nucleus, resulting in the needle opening pointing directly inferiorly in the lens during surgery. The Nagahara chopper is now inserted into the nucleus just inside the distal edge of the capsulorrhexis. In more dense nuclei, this is not always that easy. It may be facilitated by tilting the chopper upwards, so that it enters the nucleus with the sharp edge leading, in a rotatory downward movement, not straight down. The chopper enters the lens and is moved progressively deeper as it is pulled just to the left side of the phaco tip. If the phaco needle has not been advanced far enough, the lens will tend to rotate when the chopper is inserted and drawn toward the phaco tip. If this occurs, just phaco in a bit further. In softer, less brittle nuclei, the slice will not spontaneously propagate proximally as slicing progresses, and as a consequence the chopper must be drawn past the side of the phaco tip, often as far as the proximal capsulorrhexis edge. In that case, the chopper must then be replaced adjacent to the end of the phaco tip, in the slice, before separation is attempted,. The separation is better if rotation in opposite directions, rather than simply pulling, is used, because rotation causes the distal nucleus and cortex to separate into two first, and continuing the rotation causes the separation to propagate proximally. In harder, more brittle nuclei, the same is done, but in this case, the slice tends to spontaneously propagate as the chopper approaches the phaco tip, thus obviating the need to go past the phaco tip with the chopper, and making medium density nuclei the easiest cases. In very dense nuclei, it is sometimes difficult to get the chopper deep enough into the nucleus to achieve through and through slicing. If this occurs, after passing the chopper through the nucleus, do not attempt to separate, just return and slice again in the same trough in order to achieve adequate depth of penetration of the chopper.

Occasionally, especially when the technique is new to a surgeon, the first slice is incomplete, or not in the originally planned direction. This is usually due to the surgeon’s fear of going too deep, something that is actually very difficult to do. If incomplete separation occurs, do not worry, just go on to the successive

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slices. Each successive slice is easier than the last, and it does not really matter how the nucleus is sliced, as long as the pieces are small enough to be easily emulsified.

The Second and Subsequent Slices

The second slice is easier than the first, because a central depression has already been made in the nucleus, and so it is easier to get deeper with the second entry of the phaco, and easier to judge how deep you are. After completion

of the first slice the Nagahara chopper is inserted distally into the trough and the nucleus is rotated about one and one half clock hours clockwise (right-handed

surgeon). The phaco is then inserted into the distal half of the nucleus, at its right side, about one half or less clock hour from the edge, sometimes traversing the distal aspect of the proximal nuclear half in order to attain sufficient depth. The distal half is stabilized on the phaco tip, exactly as above, and the Nagahara chopper is used to create a second slice, just at the left edge of the phaco tip, in the same manner as above. Good separation is achieved, again by rotation in opposite directions. Because the first slice is the most difficult, it is wise not to aspirate this first liberated pie piece first, as it may still be attached to the right heminucleus. It is rather preferable to repeat the steps of rotation and slicing again once, a few times, or until the whole nucleus has been sliced up, before removing any pieces. The pieces are easily aspirated and emulsified by using the chopper to separate the pieces not being removed toward the left, while rotating the phaco which is holding the piece to be aspirated, to the right, thus creating ample space to aspirate out the first and subsequent pieces. Rotation of the lens pieces is easily achieved with the phaco chopper, which has a blunt rounded tip. The surgeon should, however be sure that the phaco machine is irrigating, so that the posterior capsule is taut, and not curled around the phaco chopper, when nuclear rotation is performed.

Sometimes a shelf is created with the first slice. This occurs if the phaco chopper was not inserted to full depth, and slicing therefore did not go down to the center of the lens, and the deep half of the lens was just pulled apart without any guiding slice. If this occurs, it becomes difficult to extract the nuclear pieces on one side because they are partially wrapped around a shelf of nucleus. This is resolved by just completing all of the slices around the nucleus until you get to one that is easy to remove. The rest just follow in succession. Further facilitation is achieved by going through the accidentally created nuclear shelf with the phaco, as successive pie pieces are grasped for slicing.

Completing the Procedure

Once the nucleus has been sliced, emulsified and aspirated, irrigation/aspiration of residual cortex is done in a standard fashion. The posterior capsule is then vacuumed. An additional posterior capsule cleaning trick that the author likes is to use a 6 cc syringe of BSS and a hockey stick cannula. If the cannula is allowed to be placed tangential to the plane of the posterior capsule, and the BSS is ejected in puffs, allowing the capsule to come up around the hockey stick tip between puffs, the low viscosity of BSS (1.0 mPs) causes excellent dissection of the cortical material remaining, off the posterior capsule.

160 THE ART OF PHACOEMULSIFICATION

The capsular bag and anterior chamber are then inflated with viscoelastic, the incision enlarged if needed to accommodate the intended IOL, and the IOL inserted. Viscoelastic is then removed using the authors rock and roll technique. 13 ,14 Finally, vancomycin 1 mg/0.1 cc is injected through the side port. The incision and side port are checked for leakage.

S U M M A R Y

Phaco slice and separate is the most gentle technique of phacoemulsification that the author has ever tried. It never requires any instrument to be placed out beyond the boundary of the capsulorrhexis, and consequently is very safe, and a good technique for small pupil cases. Because the nucleus is stabilized on the phaco tip before any stressful action is performed, it is also excellent for cases of pseudoexfoliation or lenticular instability or subluxation. It does, however, require a bit different mind set from older techniques of phacoemulsification, because of the lack of a sculpting step, and having to deal with multiple slices simultaneously. This change may require surgeons to take a bit of time to get used to seeing and understanding what is happening during the case. The effort, however, soon is rewarded by smoother surgery, with less concern for nuclear density and pupil size, and fewer complications. With experience, the simplification of surgery, due to the fact that the technique is relatively independent of nuclear density, pupil size and lenticular stability, makes the surgeon’s day in the operating room run much more smoothly and significantly reduces the risk of complications.

R E F E R E N C E S

1. Kelman CD: Phacoemulsification and aspiration—a new technique of cataract removal (a preliminary report). Am J Ophthalmol 64: 23-35, 1967.

2. Gimbel HV: Divide and conquer nucleofractis phacoemulsification—development and variations.

7. Fine IH, Maloney WF, Dillman DM: Crack and flip phacoemulsification technique. J Cataract Refract Surg 19:797-802, 1993.

8. Nagahara K: Phaco-chop technique eliminates central sculpting and allows faster, safer phaco.

Ocular Surgery News October 12-13, 1993.

9. Koch PS, Katzen LE: Stop and chop phacoemulsification. J Cataract Refract Surg 20:566-70, 1994.

10.Fukasaku H: Phaco snap phacoemulsification. Alcon Video Film Festival. American Society of Cataract and Refractive Surgery Annual Meeting San Diego, California, 1-5, 1995.

11.Arshinoff Steve A: Phaco slice and separate. J Cataract Refract Surg 25(4): 474-78, 1999.

12.Fine IH: Cortical cleaving hydrodissection. J Cataract Refract Surg 18:508-12, 1992.

13.Arshinoff Steve A: Rock ‘n’ Roll Removal of Healon GV. Alcon video film festival. American Society of Cataract and Refractive Surgery Annual Meeting, Seattle, Washington. June 1-5, 1996.

14.Arshinoff Steve A: Rock ‘n’ Roll Removal of Healon GV. In Arshinoff Steve A (Ed): Proceedings of the 7th Annual National Ophthalmic Speakers Program (Ottawa, Canada, June 1996). Medicopea 1997.

Eric J Arnott

I N T R O D U C T I O N

There have been more changes in cataract surgery over the last five decades than occurred over the previous three millennia. In the West the intracapsular was changed to the extracapsular cataract extraction (ECCE) in the mid 1970s, and over the last two decades this has been superseded by the phacoemulsification of the cataractous lens. In the world as a whole, these progressive changes have swept over the continents like a tidal wave. While in the USA some 97% of cataracts are performed using the ultrasonic technique, in the UK the figure is 50% and in the Asian countries some 10%. In both of these latter areas, the percentage of operations performed using ultrasound or laser, for cataract surgery, will increase over the years until “the small incision removal of the cataractous lens with insertion of an intracapsular lens implant” becomes the standard procedure.

Various factors have militated against the more rapid adoption of phacoemulsification as the standard cataract operation. Not least are the expensive surgical machinery required for its performance and the surgeons learning curve in adopting this procedure. Another important consideration is the general state of the eye and adnexa, with its cataractous lens, in the Third World, as compared to the eye with a cataract in the Western world. In Asian countries poverty, malnutrition, disease and adverse climatic conditions will often present the surgeon with a cataractous eye that cannot easily be treated with small incision cataract surgery. The Asian eye with its adnexa may have scarring of the lids, conjunctiva and cornea; resulting in an eye, which has contracted lids, misplaced lashes and a sunken immobile globe. Moreover the cornea may be semiopaque and the pupil small and non-dilatable.