Another benefit of a separate infusion stream comes to bear in polishing the posterior capsule. Focusing the flow of fluid on the posterior capsule and putting the tissue on stretch facilitates capsule polishing with either a roughened or silicone-covered aspiration tip. The taut posterior capsule shows less inclination to become entrapped in the aspiration port, and the subcapsular plaque material is more easily stripped away.

Perhaps the greatest advantage of the bimanual technique lies in its ability to remove subincisional cortex without difficulty. As originally described by Brauweiler [7], by switching infusion and aspiration hand pieces between two symmetric incisions, 360° of the capsular fornices are easily reached and cortical clean-up can be performed quickly and safely. The ability to switch hands also represents a significant advantage to instructors of phacoemulsification, who may find that they must take over a case from a resident with opposite handedness [8].

Bimanual phaco also provides significant advantages in complication management. If the posterior capsule is compromised during surgery, the first goal of the surgeon is to maintain stability of the anterior chamber to prevent both posterior migration of lens material and anterior prolapse of the vitreous. By maintaining infusion in the anterior chamber, it becomes safer to reach posteriorly with the phaco needle, aspiration tip, or vitrector, to remove residual lens tissue. Irrigation need never be brought down into the capsule where it may dislodge lens tissue, enlarge the capsular tear or engage the vitreous. Hypotony is avoided at all times by keeping the flow of irrigation constant, much in the same way that an anterior chamber maintainer works [9]. Once all lens material has been evacuated from the eye, viscoelastic may be injected prior to removal of the irrigator so that the vitreous face remains under tamponade.

Utilization of bimanual phaco for refractive lens exchange and routine cataract surgery also offers an advantage of maintaining a more stable intraocular environment during lens removal. This may be especially important in high myopes who are at a greater risk for retinal detachment following lens extraction [10]. By maintaining a formed and pressurized anterior chamber throughout the procedure, there should be fewer tendencies for anterior movement of the vitreous body with a theoretically lower incidence of posterior vitreous detachment occurring from intraoperative manipulations. Future studies will need to be performed in order

to document a significant reduction in posterior segment morbidity utilizing this method of lens removal.

Some of the major advantages we have seen from bimanual phaco do relate to incision size, for example, there has been an improvement in control of most of the steps involved in endocapsular surgery due to increase chamber stability. Since viscoelastics do not leave the eye as easily through these small incisions, the anterior chamber is more stable during capsulorhexis construction and there is much less likelihood for an errant rhexis to develop. This added margin of safety is particularly noticeable in cases of zonular compromise such as pseudoexfoliation, traumatic zonular dialysis and status post glaucoma filtering surgery, as well as in cases of intumescent cataract and nanophthalmos with a very shallow anterior chamber [11]. The added chamber stability can also make a difference in control of the capsulorhexis in high myopia with an extremely deep anterior chamber and floppy capsule. The adoption of bimanual techniques has also served as a catalyst for instrument manufacturers, who have developed delicate, exquisite forceps for the construction of the capsulorhexis.

References

1.Fine IH, Packer M, Hoffman RS. Transition to bimanual microincisionphaco.In:GargA,PandeySK,ChangDF,Papadopoulos PA, Maloof AJ (eds). Advances in Ophthalmology Interactive CD-ROM. New Delhi, Jaypee Brothers, 2005

2.Hoffman RS, Fine IH, Packer M. Bimanual micro-pha- coemulsification. In: Alio JL, Rodriguez Prats JL, Galal A (eds). MICS: Micro-Incision Cataract Surgery.El Dorado, Panama, Highlights of Ophthalmology International, 2004

3.Packer M, Fine IH, Hoffman RS. Bimanual ultrasound phacoemulsification. In: Fine IH, Packer M, Hoffman RS (eds). Refractive Lens Surgery. Heidelberg, Springer, 2005, pp 193–198

4.Fine IH, Hoffman RS, Packer M. Optimizing refractive lens exchange with bimanual micro-incision phacoemulsification. J Cataract Refract Surg 2004; 30: 550–554

5.Tehrani M, Mamalis N, Hoffman RS, Fine IH, Dick B, Packer M. Surgical correction of astigmatism. In: Gills JP (ed). A Complete Surgical Guide for Correcting Astigmatism: An Ophthalmic Manifesto. Thorofare, NJ, Slack, 2003

6.Packer M, Fine IH, Hoffman RS. Bimanual microincision phacoemulsification. In: Fine IH (ed). Perspectives in Lens & IOL Surgery. EyeWorld 2006; 11(2): 60–63; 72

7.Brauweiler P. Bimanual irrigation/aspiration. J Cataract Refract Surg 1996; 22: 1013–1016

8.Smith JH. Teaching bimanual microincision cataract surgery in a residency program. Symposium on Cataract, IOL and Refractive Surgery, ASCRS, Washington, DC, 19 April 2005

94

9.Blumenthal M. Use and results using the new ACM. Symposium on Cataract, IOL and Refractive Surgery, ASCRS, Washington, DC, 18 April 2005

10.Colin J, Robinet A, Cochener B. Retinal detachment after clear lens extraction for high myopia: seven-year follow-up. Ophthalmology 1999; 106: 2281–2284

11.Olson R. Viscoelastic to the rescue. In: Obstbaum SA (moderator), Advances in Cataract Surgery: Devices, Applications, Techniques. Ophthalmology Times Supplement 3, 1 April 2004; 29: 12–13

Take Home Pearls

ßFor the BMICS and CMICS surgeon, the Stellaris Vision Enhancement System offers

improved efficiency and safety with superior ergonomic design and flexibility.

ßAlthough smaller incision size has advantages, such as greater chamber stability and reduction

of induced astigmatism, we feel that the greatest advantage of BMICS stems from the separation of infusion and aspiration.

M. Packer et al.

ßThe advantages of micro incision phaco outweigh any increased difficulty or complications

that occur during a surgeon’s early experience with the technique.

ßThe many advantages of biaxial micro incision phaco are easily accessible to the skilled cata-

ract surgeon.

The advantages of micro incision phaco outweigh any increased difficulty or complications that occur during a surgeon’s early experience with the technique. These advantages include enhanced chamber stability thanks to a near-perfectly closed system, better followability due to the separation of infusion and aspiration, access to 360° of the anterior segment with either infusion or aspiration by switching instruments from one hand to the other, ability to use the flow of irrigation fluid as a tool to move material within the capsular bag or the anterior chamber (particularly from an open-ended irrigating chopper of the manipulator), and significantly decreased chances of vitreous prolapse in case of a posterior capsular tear, zonular dialysis, or subluxed cataracts because of the maintenance of a pressurized stream of irrigation from above.

The many advantages of biaxial micro incision phaco are easily accessible to the skilled cataract surgeon. Micro incision IOLs, already available outside the United States, will soon create a rush to these enhanced techniques. But regardless of the final incision size required for IOL insertion, micro incision phaco stands on its own as a superior technique.

M. Packer ( )

Oregon Health & Science University, Drs. Fine, Hoffman and Packer, 1550 Oak Street, Suite 5, Eugene, OR 97401, USA e-mail: mpacker@finemd.com

Separation of irrigation from the aspirating phaco needle allows for improved followability by avoiding competing currents at the tip of the needle. In some instances, the irrigation flow from the second handpiece can be used as an adjunctive surgical device – flushing nuclear pieces from the angle or loosening epinuclear or cortical material from the capsular bag. In Refractive Lens Exchange, the lens material may be washed completely out of the bag and extracted with aspiration and vacuum only, so that no ultrasound is used and no instrument enters the endocapsular space, thus increasing the safety profile of this demanding procedure. The flow of fluid from the open end of an irrigator represents a very gentle instrument which can mobilize material without trauma to delicate intraocular structures.

Another benefit of a separate infusion stream is in scrubbing troublesome plaques from the posterior capsule (Fig. 6.1). Focusing the flow of fluid on the posterior capsule and putting the tissue on stretch facilitates capsule polishing with either a roughened or siliconecovered aspiration tip. The taut posterior capsule shows less inclination to become entrapped in the aspiration port, and the subcapsular plaque material is more easily stripped away.

Perhaps the greatest advantage of the biaxial technique lies in its ability to remove subincisional cortex without difficulty. As originally described by Brauweiler, by switching infusion and aspiration hand

Fig. 6.1 Utilizing xenon slit-beam illumination highlights this posterior subcapsular plaque. The stream of irrigation fluid from the irrigating chopper is directed posteriorly to put the capsule on stretch, while the silicone sleeved aspiration tip is used to scrub away the material

Fig. 6.2 The capsulorhexis is nearly complete in this eye with a history of trauma and 90° of zonular dialysis visible temporally. The wrinkling of the capsule is a clear sign of the absence of tension. Nevertheless, because of the increased control allowed by the micro incisions which do not allow prolapse of the viscoelastic, the capsulorhexis will be centered, round, and smaller in diameter than the IOL

pieces between two micro incisions, 360° of the capsular fornices are easily reached and cortical clean-up can be performed quickly and safely. The ability to switch hands also represents a significant advantage to instructors of phacoemulsification, who may find that they must take over a case from a resident with opposite manual dominance.

Utilization of Biaxial Micro Incision Phacoemulsification for refractive lens exchange and routine cataract surgery, as we have described, offers an enormous advantage of maintaining a more stable intraocular environment during lens removal. This may be especially important in high myopes who are at a greater risk for retinal detachment following lens extraction. By maintaining a formed and pressurized anterior chamber throughout the procedure, there should be fewer tendencies for the anterior movement of the vitreous body, with a theoretically lower incidence of posterior vitreous detachment occurring from intraoperative manipulations. Future studies need to be performed in order to document a significant reduction in posterior segment morbidity utilizing this method of lens removal.

Some of the major advantages we have seen from Biaxial Micro Incision Phaco do relate to incision size, for example, there has been an improvement in the control of most of the steps involved in endocapsular surgery due to increased chamber stability. Since viscoelastics do not leave the eye easily through these small incisions, the anterior chamber is more stable during capsulorhexis construction and there is much

Fig. 6.3 Capsular dye and micro incisions help to control the capsulorhexis in this eye with a hypermature cataract

less likelihood for an errant rhexis to develop. This added margin of safety is particularly noticeable in cases of zonular compromise such as pseudoexfoliation, traumatic zonular dialysis and status post glaucoma filtering surgery, as well as in cases of intumescent cataract and nanophthalmos with a very shallow anterior chamber (Figs. 6.2 and 6.3). The added chamber stability can also make a difference in the control of capsulorhexis in high myopia with an extremely deep anterior chamber and floppy capsule. The adoption of Micro Incision techniques has also served as a catalyst for instrument manufacturers, who have developed delicate, exquisite forceps for the construction of the

capsulorhexis. The result has been unparalleled surgical control. Hydrodelineation and hydrodissection can also be performed more efficiently by virtue of a higher level of pressure building in the anterior chamber, prior to the eventual prolapse of viscoelastic through the Micro Incisions.

In order to reap the benefit of these advantages strict attention to detail is required. The first technique to master is the construction of the incision. There is a variability in incision size among surgeons who employ 20, 19 gauge and even 18 gauge instrumentation. We prefer 20 gauge because we feel it offers greater control. Because the outer diameter of the 20 gauge tip is 0.9 mm, the circumference of the tip is 2.8 mm and the incision must measure 1.4 mm. An incision smaller than 1.4 mm stretches and tears, causing loss of selfsealability. These micro incisions are converted from a line to a circle upon introduction of the tip, and we want them to resume the configuration of a line when the tip is withdrawn. Compromise of the corneal collagen by stretching or tearing will reduce the likelihood that the incision will resume its virgin architecture at the end of the case. This can be minimized by using only trapezoidal-shaped incisions. There are now available from a variety of manufacturers, diamond and metal knives specially designed for the construction of 20 or 19 gauge incisions. It behooves the surgeon to purchase and learn to use this instrumentation, whether constructed of steel, diamond or other material.

Capsulorhexis construction represents the initial hurdle in the biaxial learning curve. However, micro incision capsulorhexis forceps permit a greater degree of precision and control, so much so that we advocate their use with any size of incision. The pinch type initiation of the capsulorhexis is particularly valuable in cases of zonular compromise since the forces acting on the capsule remain balanced. Even with a severely wrinkling capsule due to traumatic zonular dialysis, these extraordinarily delicate forceps permit moment-by- moment control of the capsulorhexis. With new technology IOLs, such as the crystalens (Bausch & Lomb, San Dimas, CA), we have found capsulorhexis size to be an important determinant of the final lens position and, therefore, of postoperative refractive status. Using micro incisions enhances the precision of capsulorhexis construction not only because of the improvements in instrumentation, but also because there is no tendency for the chamber to shallow as often occurs with a 2.5 mm incision due to burping of the viscoelastic.

There is an increased risk of losing control of the capsulorhexis in highly myopic eyes with very large, floppy capsules. Due to the extremely long anterior chamber depth in these eyes, the angle of approach to the anterior capsule is much steeper. If one notices that the capsulorhexis is tearing out further peripherally than one would like, a simple technique for capsulorhexis recovery involves laying down the flap and pulling centripetally. This maneuver redirects the capsulorhexis centrally [1]. In extreme cases, it may be necessary to cut the flap with scissors and begin the tear a new.

The goal of cortical cleaving hydrodissection as described by Howard Fine is to lyse the equatorial capsular–cortical connections, which will generally allow aspiration of the cortex, along with the mobilization of the epinucleus [2]. Hydrodelineation is performed to allow free mobility of the endonucleus within the epinuclear shell, allowing endocapsular nuclear disassembly within the safety cushion of the epinucleus. Hydrodissection and hydrodelineation may be performed just as they are with standard small incision surgery; the micro incisions do allow egress of the viscoelastic during this step so that there is not an increased risk of blowing out the posterior capsule due to overpressurization. It is of note that the intraocular pressure during hydrodissection, as measured in the vitreous cavity of a cadaver eye, varies around means of 78–223mmHg, regardless of whether a standard small incision or a micro incision is employed [3]. These were among the highest pressures we recorded during the entire phacoemulsification and IOL implantation procedure. Clearly, if the viscoelastic is prevented from exiting the eye, there is adequate pressure to rupture the capsule. This represents a special concern to users of high zero shear viscosity OVDs, who should insure that a path for egress is prepared with a track of balanced salt solution from the cannula tip to the incision.

A variety of irrigating choppers are now available for micro incision surgery. The method of placing the blade or the paddle of the chopper through the incision is not always immediately apparent. With the canoe paddle shaped Tsuneoka chopper (Du-02317, MicroSurgical Technologies, Redmond, WA), for example, the paddle must be placed parallel to the incision, inserted into the chamber and then rotated to allow full entry. Surgical videos are generally available from industry for instructional purposes. Placing the phaco tip through the incision may also be harder than it first appears. A 30° tip may be inserted into the incision bevel down, and then

rocked gently from side to side to permit passage into the chamber.

The surprising fact about horizontal and vertical chopping techniques with biaxial phaco is how little they differ in terms of hand movement from the standard small incision coaxial phaco. Seeing the bulkier irrigating chopper in the eye and getting used to the heavier feel in one’s hand represent the major differences; the actual chopping techniques are the same. The stream of irrigation fluid from the chopper or manipulator can function as an efficient tool within the eye and is one of the most significant advantages of biaxial phaco, which is a key reason we do not want to go back to coaxial phaco. In particular, washing subincisional endoor epinuclear material into the range of the phaco tip permits enhanced safety and control. A great example is Refractive Lens Exchange with an accommodative IOL in high myopia, probably the situation in which we are most concerned about maintaining the integrity of the capsule. Not only would compromising the capsule increase the risk of posterior segment complications, but it may also result in an inability to implant the IOL of choice for the procedure. With biaxial RLE, no instrument other than a cannula and a stream of fluid ever need enter the endolenticular or endocapsular space; we can hydroexpress the soft lens material into the anterior chamber with the stream of the irrigation fluid and carousel it safely from the eye with fluidics alone [4]. Thanks to cortical cleaving hydrodissection, we can achieve a clean capsule without ever placing an aspiration tip below the level of the capsulorhexis. The absence of ultrasound energy allows for the safest, minimally invasive procedure. The margin of safety is further enhanced by this approach.

If there is a breach of the posterior capsule, residual lens material can generally be removed while maintaining irrigation in the anterior chamber and disallowing vitreous prolapse. With biaxial phaco, we have the option of switching from a phaco tip to an aspirator to a vitrector if necessary, without ever compromising chamber stability. The approach, once a tear is recognized, consists of continuous irrigation in the anterior chamber while the lens material is removed from the bag. Once the bag is clean, a dispersive viscoelastic is injected at the level of the posterior capsule while irrigation is still maintained; only when the viscoelastic has fully tamponaded the break and filled the chamber is the irrigator removed. The IOL can then be inserted into the ciliary sulcus and capsule through a standard temporal clear corneal incision between the microincisions. In

the case of sulcus placement, the optic is pushed posteriorly through the capsulorhexis prior to final clean up. In compromised posterior capsules, residual viscoelastic is removed from the anterior chamber with a vitrector. Once the viscoelastic is removed, the kenalog technique described by Scott Burke is utilized to insure a completely vitreous-free environment in the anterior segment.

We have found this technique to be simple, efficacious, and safe, since most of the lens extraction is occurring in the plane of the iris, away from the posterior capsule and the corneal endothelium. Whether surgeons employ 18 or 21 gauge incisions, the principle advantages of B-MICS Phaco arise from the separation of infusion and aspiration. No matter how small the incision, these advantages cannot be achieved with coaxial techniques.

B-MICS: Take Home Pearls

ßDetails are very important with this technique – it is not very forgiving. Carefully follow an

experienced B-MICS surgeon’s recommendations for settings and phaco tips specific to your phaco machine.

ßBalancing inflow and outflow is critical. Most initial difficulties relate to chamber stability

and fluid dynamics.

ßConversation with an experienced B-MICS surgeon is extremely helpful – both for prepa-

ration before and for troubleshooting after the initial cases.

ßSurgical equipment representatives are additional good resources for technical informa-

tion and optimization of power and fluidic parameters.

ßHave a phaco machine surgical representative present in the OR for the first few cases to

adjust the machine settings during surgery as needed. This leaves the nurses/techs free to concentrate on the new procedure steps and equipment. A representative with B-MICS experience is best of all.

ßDecrease aspiration flow rates for initial B-MICS cases because, due to the smaller cali-

ber of the irrigator, effective aspiration flow rates are higher with B-MICS than in coaxial phaco. This results in faster movement of material within the eye at a given aspiration setting.

ßDecrease the vacuum setting for initial B-MICS cases to help prevent chamber fluctuations due

to post-occlusion surge. Once the flow parameters are worked out and the chamber is stable, vacuum can be gradually increased.

ßThe phaco tip is used without a sleeve, but it is useful to place a cut-off sleeve on the phaco

handpiece to prevent spraying of BSS during ultrasound. The sleeve must be cut off very close to the hub – if the stump of the sleeve is longer than about 1 mm, it can limit the phaco tip’s excursion into the eye.

ßInitially, B-MICS makes nuclear disassembly easier in some aspects and more difficult in

others. It is made easier by improved chamber stability and followability, and it is made more difficult by the bulkier irrigating choppers and smaller, more restrictive incisions. Once adjusted to the instruments and smaller incisions, however, B-MICS is a superior technique for nuclear disassembly.

References

6.1Pupil Dilation and Preoperative Preparation

Mark Packer, I. Howard Fine,

and Richard S. Hoffman

Core Messages

ßManagement of small pupil may be successfully accomplished by means of any one or a

combination of the following techniques:

−Pharmacologic mydriasis

−Viscomydriasis

−Pupillary stretching techniques

−Pupil ring expanders

−Iris surgery

ßPreoperative preparation accomplishes multiple goals, including infection prophylaxis. Pre-

venting infection is a multi-factorial process involving positioning, prepping, and draping of the patient, and the use of antibiotics as well as surgical technique.

1.Little BC, Smith JH, Packer M (2006) Little capsulorhexis tear-out rescue. J Cataract Refract Surg 32:1420–1422

2.Fine IH (2000) Cortical cleaving hydrodissection. J Cataract Refract Surg 26(7):943–944

3.Khng C, Packer M (2004) Intraocular pressure during phacoemulsification [poster]. In: XXII Congress of the European Society of Cataract and Refractive Surgery, Paris, 18–22 September 2004

4.Fine IH, Hoffman RS, Packer M (2004) Optimizing refractive lens exchange with bimanual microincision phacoemulsification. J Cataract Refract Surg 30:550–554

6.1.1Managing the Small Pupil

The pupil that dilates poorly or is fibrosed or hyalinized is frequently associated with complications during cataract surgery. With endolenticular techniques, especially with nucleofractis procedures and chop techniques [1–4], pupils do not need to be as large as previously required. This is because, much of the procedure takes place in the endolenticular space, within the center of the capsulorhexis, rather than at the equator of the lens as in anterior chamber phacoemulsification [5] and nuclear tilt pupillary plane phacoemulsification techniques [6]. However, there are still numerous instances in which the pupil is inadequate to allow the surgeon to proceed and some form of manipulation or surgery is required.