Ординатура / Офтальмология / Английские материалы / Bimanual Phaco Mastering the Phakonit MICS Technique_Agarwal_2004

5.Chang DF. Can brunescent lenses be removed with “cold” phaco? Presented at: ASCRS meeting; 2002; Philadelphia Pa.

6.Chang DF (moderator). Technological advances in cold phaco. Cataract and Refractive Surgery Today. 2002;July(suppl).

7.Hayashi K, Hayashi H, Nakao F, Hayashi F. Risk factors for corneal endothelial injury during phacoemulsification. J Cataract Refract Surg. 1996;22:1079-1084.

8.Chang D. Converting to phaco chop: why? which technique? how? Ophthalmic Practice. 1999; 17(4):202-210.

9.Pirazzoli G, D’Eliseo D, Ziosi M, Acciarri R. Effects of phacoemulsification time on the corneal endothelium using phacofracture and phaco chop techniques. J Cataract Refract Surg. 1996;22: 967-969

10.Chang DF. Phaco Chop: Mastering Techniques, Optimizing Technology, and Avoiding Complications. Thorofare, NJ: SLACK Incorporated; 2004.

Chapter

12

BIMANUAL PHACO:

SURGICAL TECHNIQUE

Amar Agarwal, MS, FRCS, FRCOphth

TECHNIQUE OF BIMANUAL PHACO FOR CATARACTS

Anesthesia

The technique of bimanual phaco (ie, Phakonit, MICS, microphaco, or sleeveless phaco) can be done under any type of anesthesia. In the cases done by the author, no anesthetic drops are instilled in the eye, nor is any intracameral anesthetic injected inside the eye. This is known as no anesthesia cataract surgery. The author has analyzed that there is no difference between topical anesthesia cataract surgery and no anesthesia cataract surgery. If there is a difficult case, the author uses a peribulbar block.

Incision

In the first step, a needle with viscoelastic is taken and pierced in the eye in the area where the side-port has to be made (Figure 12-1). The viscoelastic is then injected inside the eye. This will distend the eye so that the clear corneal incision can be made. Now a temporal clear corneal incision is made. A special knife can be used for this purpose. (Figure 12-2). This keratome and other instruments for bimanual phaco are made by Huco (Switzerland), Gueder (Heidelburg, Germany), and Microsurgical Technologies (MST, Redmond, Wash).

Rhexis

The rhexis of about 5.0 to 6.0 mm is then performed. This is done with a needle (Figure 12-3). In the left hand, a straight rod is held to stabilize the eye; this is the globe stabilization rod. The advantage of this is that the movements of the eye can be controlled as one is working without any anesthesia.

Hydrodissection

Hydrodissection is performed and the fluid wave passing under the nucleus is checked. (Check for rotation of the nucleus.)

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Figure 12-1. A 26-gauge needle with viscoelastic making an entry in the area where the side-port is. This is for entry of the irrigating chopper.

Figure 12-2. Clear corneal incision made with the keratome. Note the left hand has a straight rod to stabilize the eye as the case is done without any anesthesia. These instruments are made by Katena (Denville, NJ).

Figure 12-3. Rhexis started with a needle.

Figure 12-4. Bimanual phaco irrigating chopper and phaco probe without the sleeve inside the eye.

Bimanual Phaco

After enlarging the side-port a 20or 21-gauge irrigating chopper connected to the infusion line of the phaco machine is introduced with foot pedal on position 1. The Agarwal irrigating chopper, specially designed by Larry Laks from United States, has been made by MST and incorporated into the Duet system. Other excellent irrigating choppers by the same company include the ones designed by David Chang, Randall Olson, Robert Osher, I. Howard Fine, and Hiroshi Tseunoka. Other Agarwal irrigating choppers are available with Geuder, Huco, and Katena. The phaco probe is connected to the aspiration line, and the phaco tip without an infusion sleeve is introduced through the clear corneal incision (Figure 12-4). Using the phaco tip with moderate ultrasound power, the center of the nucleus is directly embedded starting from the superior edge of rhexis with the phaco probe directed obliquely downward towards the vitreous. The settings at this stage is 50% phaco power, flow rate 24.0 mL/min, and 110.0 mmHg vacuum (Alcon Univ II phaco machine). When nearly half of the center of nucleus is embedded, the foot pedal is moved to position 2, helping to hold the nucleus due to vacuum rise. To avoid undue pressure on the posterior capsule, the nucleus is lifted a bit and with the irrigating chopper in the left hand the nucleus chopped. This is done with a straight downward motion from the inner edge of the rhexis to the center of the nucleus and then to the left in the form of a laterally reversed L shape (Figure 12-5). Once the crack is created, the nucleus is split to the center. The nucleus is then rotated 180 degrees and cracked again so that the nucleus is completely split into two halves.

The nucleus is then rotated 90 degrees and embedding is done in one half of the nucleus with the probe directed horizontally (Figure 12-6). With the previously described technique, three pie-shaped quadrants are created in one half of the nucleus. Similarly, three pie-shaped fragments are created in the other half of the nucleus. With a short burst of energy at pulse mode, each pie-shaped fragment is lifted and brought at the level of iris where it is further emulsified and aspirated sequentially in pulse mode. Thus the whole nucleus is removed (Figure 12-7). Note in Figure 12-7, no corneal burns are present. Cortical wash-up is the done with the bimanual irrigation aspiration technique (Figures 12-8 and 12-9).

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Figure 12-5. Bimanual phaco started. Note the phaco needle in the right hand and an irrigating chopper in the left hand. Bimanual phaco being performed. Not the crack created by “karate” chopping. The assistant continually irrigates the phaco probe area from outside to prevent corneal burns.

Figure 12-6. Bimanual phaco continued. The nuclear pieces are chopped into smaller pie-shaped fragments.

Figure 12-7. Bimanual phaco completed. Note the nucleus has been removed and there are no corneal burns.

Figure 12-8. Bimanual irrigation aspiration started.

Figure 12-9. Bimanual irrigation aspiration completed.

BIMANUAL PHACO WITH CUT SLEEVE

Another unique problem faced during bimanual phaco was that of fluid splashing from the base of the phaco needle outside the incision during emulsification. This splashing is due to the fact that the fluid in contact with the base of the vibrating phaco needle during emulsification was churned, thus releasing droplets of fluid. These fluid droplets could hamper the surgeon’s view directly or by getting deposited on the microscope objective.

To eliminate wound burns, we should have some way of cooling the corneal wound of entry. This is usually remedies by the fluid that leaks out of the eye from the main wound, since the naked phaco needle without the sleeve does not provide a water tight wound. To provide irrigation into the anterior chamber, we use the irrigating chopper through the side-port connected to the irrigating bottle along with an air pump specially devised for this purpose. To prevent the splashing of fluid from the base of the needle during emulsification, we use the cut sleeve around the base of the phaco needle. We cut the sleeve in such a manner that it covers only the base of the phaco needle and does not enter the eye. Thus, we are able to prevent the splashing of fluid during emulsification.

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During bimanual phaco surgery, fluid is constantly leaking out of the eye from the main wound of entry, as the incision around the phaco needle without the sleeve is not watertight. This fluid is coming from the irrigating chopper connected to the air injector. If we connect another fluid irrigating line the phaco needle with cut sleeve, fluid travels from the base of the phaco needle towards the wound of entry from outside. This stream of fluid meets the stream coming from inside eye at the corneal entry wound causing turbulence and fluid collection in the operating field. This reduces visibility during surgery. Moreover, since the wound is cooled internally by the fluid leaking from the eye outward, there is no need for this second irrigation line. More importantly, when we connect the second irrigation line to the phaco hand piece with the cut sleeve, the irrigation is always on but we need it only during emulsification. Hence, it is better to use an assistant who could drop cooled BSS at the external wound only during emulsification. We advocate bimanual phaco with a cut sleeve without irrigation to eliminate water splashing during bimanual phaco to improve visibility during the surgery.

AIR PUMP

One of the real concerns when we started bimanual phaco was the problem of destabilization of the anterior chamber during surgery. This was solved to a certain extent by using an 18-gauge irrigating chopper. A development made by Sunita Agarwal was to use an anti-chamber collapser4,5 which injects air into the infusion bottle (see Chapter 7). This is an air pump. This pushes in more fluid into the eye through the irrigating chopper and also prevents surge. Thus we were not only able to use a 20gauge irrigating chopper but also solve the problem of destabilization of the anterior chamber during surgery. This increases the steady-state pressure of the eye making the anterior chamber deep and well maintained during the entire procedure. It even makes phacoemulsification a relatively safe procedure by reducing surge even at high vacuum levels. Thus, this can be used not only in bimanual phaco but also in phacoemulsification.

BIMANUAL PHACO CAN BE DONE

WITH ANY PHACO MACHINE

A top-end phaco machine is not required to perform bimanual phaco. The key is to use any machine already present and start bimanual phaco. The parameters for an Alcon (Fort Worth, Tex) or AMO machine are:

•Power: 50% phaco power for a moderate cataract. The power can be increased to 70% for hard cataracts. Start in the continuous mode and once chopping has been done then shift to the pulse mode.

•Suction: 100.0 mmHg. One has to use the air pump or anti chamber collapser so that no surge occurs. In other words some sort of forced gas infusion has to be used. One can do without it but the problem will come in difficult cases and one has to go slower.

•Flow rate: 20.0 to 24.0 mL/min.

•Phaco needle: if one uses a 0.8-mm phaco needle with a 21-gauge irrigating chopper then one can do a sub-1.0-mm cataract surgery.

•Irrigation over corneal incision. It is better than not applying it. You can feel very safe with it as it negates the possibility of a corneal burn.